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Semantically Rich 3D Building and Cadastral Models for Valuation

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Abstract and Figures

Valuation of real estate/ properties is in many countries/ cities the basis for fair taxation. The value depends on many aspects, including the physical real world aspects (geometries, material of object as build) and legal/virtual aspects (rights, restrictions, responsibilities, zoning/development plans applicable to the objects spaces). Current property valuation and taxation seems not to be significantly benefiting from digital 3D building models and/or 3D Cadastres as a result of low awareness regarding the possibilities provided by semantically rich 3D models. The current valuation practices in various countries are analyzed: Turkey, United Kingdom, USA, Germany, and the Netherlands. The (possible) role of semantically rich 3D building models and 3D cadastres in relation to valuation and taxation is explored.
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35
Umit Isikdag, Mike Horhammer, Sisi Zlatanova, Ruud Kathmann and Peter van Oosterom
Semantically Rich 3D Building and Cadastral Models for Valuation
4
th
International Workshop on 3D Cadastres
9-11 November 2014, Dubai, United Arab Emirates
Semantically Rich 3D Building and Cadastral Models for Valuation
Umit ISIKDAG, Turkey, Mike HORHAMMER, USA, Sisi ZLATANOVA,
Ruud KATHMANN and Peter VAN OOSTEROM, the Netherlands
Key words: Valuation, 3D Models, CityGML, IFC, 3D Cadastre
SUMMARY
Valuation of real estate/ properties is in many countries/ cities the basis for fair taxation. The
value depends on many aspects, including the physical real world aspects (geometries,
material of object as build) and legal/virtual aspects (rights, restrictions, responsibilities,
zoning/development plans applicable to the objects spaces). Current property valuation and
taxation seems not to be significantly benefiting from digital 3D building models and/or 3D
Cadastres as a result of low awareness regarding the possibilities provided by semantically
rich 3D models. The current valuation practices in various countries are analyzed: Turkey,
United Kingdom, USA, Germany, and the Netherlands. The (possible) role of semantically
rich 3D building models and 3D cadastres in relation to valuation and taxation is explored.
36 Umit Isikdag, Mike Horhammer, Sisi Zlatanova, Ruud Kathmann and Peter van Oosterom
Semantically Rich 3D Building and Cadastral Models for Valuation
4
th
International Workshop on 3D Cadastres
9-11 November 2014, Dubai, United Arab Emirates
Semantically Rich 3D Building and Cadastral Models for Valuation
Umit ISIKDAG, Turkey, Mike HORHAMMER, USA, Sisi ZLATANOVA,
Ruud KATHMANN and Peter VAN OOSTEROM, the Netherlands
1. INTRODUCTION
Valuation of real estate/ properties is in many countries/ cities the basis for fair taxation. The
property value depends on many aspects, including the physical real world aspects
(geometries, material of object as build) and legal/virtual aspects (rights, restrictions,
responsibilities, zoning/development plans applicable to the objects spaces). The aim of this
study is to investigate the opportunities provided by the semantically rich 3D building and
cadastral models for valuation and taxation. In this paper we investigate the following related
aspects:
1. Relationship between physical real world objects and legal (virtual) objects,
2. Use of (semantically rich) 2D and 3D descriptions of both physical real world objects
and legal (virtual) objects for valuation, and
3. Maintenance of the 3D information.
Section 2 provides some background on building models (physical objects) and cadastral
models (legal/ virtual objects) and their relationships. In Section 3 of the paper we analyze the
current valuation practices in various countries: Turkey, United Kingdom, USA, Germany,
and the Netherlands. Then we discuss in Section 4 the possible role of semantically rich 3D
building models and 3D cadastres in relation to improved valuation in the future. In the
conclusion of the paper (Section 5), it is further discussed how these models should be kept
consistent, accurate and up-to-date over the years.
2. BACKGROUND ON BUILDING AND CADASTRAL MODELS AND DATA
In this section first the state of the art of (physical) building information models and data are
presented in Subsection 2.1. In the next subsection (2.2), an introduction is given of the
information models and data in land administration (concerning legal/ virtual objects). The
relationship between physical and virtual objects is discussed in Subsection 2.3.
2.1 Building models (physical objects)
The representation of physical buildings with digital building models has been a subject of
research since four decades in the fields of Construction Informatics and GeoInformation
science. The early digital representations of buildings mainly appeared as 3D drawings
constructed by CAD software, and the 3D representation of the buildings was only geometric,
while semantics and topology were out of modeling focus. On the other hand less detailed
building representations, with often focus on ‘outside’ representations, were also found in
form of 2D /2,5D GeoInformation models These models contain geometry and linked
semantic information in compliance with the feature model of the GIS domain (as explained
in ISO 19125-1). Since the start of 2000s, detailed models containing geometric, topology and
semantic information have began to emerge with the advent of Building Information Models.
37
Umit Isikdag, Mike Horhammer, Sisi Zlatanova, Ruud Kathmann and Peter van Oosterom
Semantically Rich 3D Building and Cadastral Models for Valuation
4
th
International Workshop on 3D Cadastres
9-11 November 2014, Dubai, United Arab Emirates
Isikdag & Underwood (2010) defined Building Information Modeling as “the information
management process throughout the lifecycle of a building (from conception to demolition)
which mainly focuses on enabling and facilitating the integrated way of project flow and
delivery, by the collaborative use of semantically rich 3D digital building models in all stages
of the project and building lifecycle”. From this same perspective a Building Information
Model(s), i.e. BIMs can be defined as “the (set of) semantically rich shared 3D digital
building model(s) that form(s) the backbone of the Building Information Modeling process”.
These models are capable of containing geometric/semantic information regarding the
building indoors and outdoors, in a very high level of detail (i.e. models can be regarded as
LOD , or LOD N models), where a model in some cases contain the geometry/semantics of
nut & bolt or a picture frame in the house. The complexity of the BIMs (in terms of object
relations) is very high and furthermore as the population of the entity instances (i.e. the data)
of the model increases, it becomes costly to store and perform advanced queries on the
models. Another model that is found valuable in 3D representation of buildings, has its roots
in geoinformation modeling. A well known schema of GML (an OGC standard which is
developed mainly for the exchange of geoinformation), namely CityGML (OGC,2012, Gröger
and Plümer, 2012), offers digital representation of models in different levels of details, LOD 4
of the model offers possibilities of indoor representation. As explained by OGC City
Geography Markup Language (CityGML) Encoding Standard (2012), “Buildings may be
represented in LOD0 by footprint or roof edge polygons. LOD1 is the well-known blocks
model comprising prismatic buildings with flat roof structures. In contrast, a building in
LOD2 has differentiated roof structures and thematically differentiated boundary surfaces.
LOD3 denotes architectural models with detailed wall and roof structures potentially
including doors and windows. LOD4 completes a LOD3 model by adding interior structures
for buildings. For example, buildings in LOD4 are composed of rooms, interior doors, stairs,
and furniture.”
2.2 Land administration (legal/virtual objects)
Land administrations systems (land registry, cadastre) have different origins in different
countries. The information was sometimes collected for taxation purposes and in other cases
for legal security. Over the years, in many countries the land administration systems more and
more served both applications; e.g. in the area of spatial development or spatial planning. In
this context the term multi-purpose cadastre is used. Based on the initiative of the FIG
(International Federation of Surveyors), ISO has developed the standard Land Administration
Domain Model (LADM), ISO 19152:2012. In the standard, land administration is described
as the process of determining, recording and disseminating information about the relationship
between people and land (or rather ‘space’). The LADM standard defines a basic
administrative unit (‘basic property unit’) as an administrative entity, subject to registration
(by law), or recordation, consisting of zero or more spatial units (‘parcels’) against which (one
or more) unique and homogeneous RRRs (rights, e.g. ownership right or land use right,
responsibilities or restrictions) are associated to the whole entity, as included in a land
administration system. A parcel can be described by 2D or 3D geometry or even by textual
descriptions (Lemmen at al, 2010). Homogenous means that the same combination of RRRs
equally apply within the whole spatial unit. Unique means that this is the largest spatial unit
for which this is true. Making the unit any larger would result in the combination of rights not
being homogenous. Making the unit smaller would result in at least 2 neighbor parcels with
38 Umit Isikdag, Mike Horhammer, Sisi Zlatanova, Ruud Kathmann and Peter van Oosterom
Semantically Rich 3D Building and Cadastral Models for Valuation
4
th
International Workshop on 3D Cadastres
9-11 November 2014, Dubai, United Arab Emirates
the same combinations of rights. The objects (parcels) are called legal or virtual objects,
because they do not need to be visible in the real world. However, it should be noted that
quite often the boundary of a parcel coincides with a physical real world object; e.g. a fence,
wall, edge of road. In case of 3D parcels, this is even more true; e.g. the geometries of
physical objects such as tunnels, building (parts) or other constructions correspond also to
legal spaces with unique and homogeneous RRRs attached. Perhaps valuation is not directly a
3D cadastre topic, but is it strongly related, because most property tax systems are one way or
the other based on an assessed value of the property and relevant in context of multi-purpose
cadastre.
2.3 Relationship between physical and virtual objects
A (3D) building registration is something else than a (3D) Cadastre. Cadastre is about the
legal spaces. That is, spaces described by geometry (and topology) where certain rights,
restrictions or responsibilities (RRRs) are attached to. So, all kinds of building details, such as
different rooms/ spaces, may not always be relevant (when same RRRs apply). Only when the
RRRs are different then also a separate geometry is needed. So, most likely only a part of the
indoor building modeling information may be relevant in 3D Cadastre context (and perhaps
that geometry is even implicit; e.g. a 3D boundary defined by the ‘middle of the wall’). The
geometries of the real world (physical) objects and the geometries of the legal objects should
be consistent and we should design rules for this. Further, one could argue that when in a
certain jurisdiction one has the responsibility to pay certain amount of tax based on the
function/ type of a room/ space in a building, then this would fall under the definition of a
legal space. This will further reinforce the link between 3D cadastre and building models. The
Annex K from ISO 19152 (Figure 1), is a UML diagram showing in color core classes of the
LADM standard: green, LA_Party (person), yellow, LA_RRR (right, etc. such as
ownership)/LA_BAUnit in blue, LA_SpatialObject (parcel) and showing not in color the
LADM external classes (with stereotype <<blueprint>>, e.g. ExtTaxation, ExtValuation).
LA_BAUnit stands for basic administrative unit, a group of LA_SpatialObjects with same
RRRs attached. LA_SpatialObject has several specializations, such as
LA_LegalSpaceNetwork (shown in diagram, including link to ExtNetwork, the physical
network registration) and LA_LegalSpaceBuildingUnit (not shown in diagram, but could be
linked to physical building registration). LADM is more a conceptual framework defining
concepts and terminology, than prescriptive standard. A country should first develop an
LADM country profile supporting the legislation of the country (and described in concepts of
the international standard), before transforming this into a land administration
implementation.
39
Umit Isikdag, Mike Horhammer, Sisi Zlatanova, Ruud Kathmann and Peter van Oosterom
Semantically Rich 3D Building and Cadastral Models for Valuation
4
th
International Workshop on 3D Cadastres
9-11 November 2014, Dubai, United Arab Emirates
Figure 1. LADM Core classes (in color and ‘LA_’ prefix) and LADM external classes (with ‘Ext’ prefix),
taken from ISO 19152:2012
40 Umit Isikdag, Mike Horhammer, Sisi Zlatanova, Ruud Kathmann and Peter van Oosterom
Semantically Rich 3D Building and Cadastral Models for Valuation
4
th
International Workshop on 3D Cadastres
9-11 November 2014, Dubai, United Arab Emirates
3. VALUATION IN VARIOUS COUNTRIES
In this section we will analyze the various valuation approaches and the role of 2D/3D
geometries in countries such as: Turkey, United Kingdom, USA, Germany, and the
Netherlands (in Subsection 3.1 to 3.5). The section is concluded with a short analysis on the
potential use of 3D geometries for the purpose of valuation (Subsection 3.6).
3.1 Turkey
There are 2 different types of valuations. The first one is regarding the sales of the properties
to calculate the market value, and the second one is valuation for taxation. The two types have
many similarities in calculations and some small differences.
Determining the Market Value The first type is called Real Estate Appraisal or Real Estate
Valuation. In Turkey, experts in this field work as ‘government certified valuation experts’.
There are 3 commonly used methods for determining the market value of the built properties:
a) The first one is comparison with a reference sales price approach. This method
includes finding a set of similar properties, comparing the attributes of the property-in-
focus with these similar properties and estimating the value of the property.
b) The second method of valuation is income approach; e.g. such as rent. There are
several techniques in use with this approach.
c) The third method for valuation is the cost approach. When this approach is used the
value of the land lot needs to be calculated separately and added to the value of the
building, in order to find overall value of the property. There are also several
techniques in use with this approach. The land lot valuation uses “total floor area”
based valuation for residential buildings, and “total building volume” based valuation
in industrial buildings by using zoning parameters such as Building Coverage Ratio
(BCR) and Floor Area Ratio (FAR) and HMax (maximum allowable building height).
Determining the Taxation Value The valuation for the purpose of taxation is accomplished
by local or greater municipalities in Turkey. The valuation of the houses and flats are
determined by valuation commission of the municipalities. The tax is known as the property
tax. The law regarding the property tax is Law No. 1319. The regulations that explains how
the taxation value of the house would be determined, is dated 29.02.1972 as Cabinet Council
Decision 7/3995. As mentioned in Bal (2014) according to this regulation there are 3 methods
for valuation.
a) First one is comparison method. This method is similar to the first approach of market
value determination. The similarity between the property in focus and other properties
that the sales prices would be compared needs to be similar in terms of 1. use
(Residential, Office, Other Specific Building), 2. building construction type (Steel
Framework, Concrete Framework, Stone, Stone Frame, Timber, Shanty, Sun-dried /
Mud Brick), 3. building quality (Luxury, Class 1, Class 2, Class 3, Simple
Construction) and 4. comparison factors (proximity to businesses/ parking/ gardens/
schools/ public transportation/ seafront/ main road; existence of urban infrastructure:
gas, electricity, sewerage; dimensions of the property, number of rooms; comfort,
elevator, heating/ ventilation/ air conditioning; landscape that can be viewed).
41
Umit Isikdag, Mike Horhammer, Sisi Zlatanova, Ruud Kathmann and Peter van Oosterom
Semantically Rich 3D Building and Cadastral Models for Valuation
4
th
International Workshop on 3D Cadastres
9-11 November 2014, Dubai, United Arab Emirates
b) The second method of valuation is income method. This method is much simpler than
the similar approaches presented in section for market valuation. The Annual Gross
Income is calculated as Average Annual Rent that can be earned in the neighborhood
of that property. The value of the property is then determined as: Asset Cost = Annual
Gross Income x 10.
c) The third method is costing method. When this method is used the value of the land lot
needs to be calculated separately. In this method the value of the property is calculated
as follows: Asset Cost= Gross Floor Area x Unit Cost with Unit Cost= Cost of 1 sqm.
of the building based on its building type, use and quality. The Unit Cost charts are
published and distributed by the Ministry of Finance every year.
In the current practice neither the facade areas of the buildings nor the floor plan areas are
derived from the digital building models, in addition the factors such as having heating/
ventilation/ air conditioning are not checked using the models. It is foreseeable that the efforts
towards the use of 3D semantically rich building models for valuation would be beneficial for
the process. From the viewpoint of the comparison approach it will definitely provide
opportunities for better comparison based on factors listed. From the viewpoint of the costing
approach, the use 3D models will form a basis for preparation of detailed and accurate costing
(e.g. using quantity surveying method), in addition the floor level also has an impact on
costing for taxation.
3.2 United Kingdom
In the UK the valuation of the houses are done by the UK Government Valuation Office
Agency, mainly for forming the base for Council Tax calculation. As explained in Valuation
Agency (VOA, 2014) ‘Understanding your Council Tax Banding’, the Council Tax in
England is a local tax based on what a home would have sold for at a fixed point in time:1
April 1991. The income from council tax is collected by local councils to help pay for local
services. The table below shows the range, based on 1 April 1991 values, for each band in
England. Each year, the local council sets the level of council tax and can tell you the amount
payable, for each band.
Valuation Band Open Market Value as at 1 April 1991
Band A Not more than £40,000
Band B £40,001 to £52,000
Band C £52,001 to £68,000
Band D £68,001 to £88,000
Band E £88,001 to £120,000
Band F £120,001 to £160,000
Band G £160,001 to £320,000
Band H More than £320,000
In UK taxation scheme a property is defined as “A separate unit of living accommodation,
occupied by the same person(s) and within the same area of land, comprises a ‘dwelling’,
together with any garden, yard, garage or other outbuildings attached to it. In tax calculations
each property is allocated to one of the eight bands, A to H, (‘A’ being the lowest) according
to its national value on 1 April 1991. As explained by VOA, the agency takes account of the
42 Umit Isikdag, Mike Horhammer, Sisi Zlatanova, Ruud Kathmann and Peter van Oosterom
Semantically Rich 3D Building and Cadastral Models for Valuation
4
th
International Workshop on 3D Cadastres
9-11 November 2014, Dubai, United Arab Emirates
size, age and character of the property as well as its location when allocating a council tax
band. This allocation of a band is in fact a valuation of the property with a very limited
accuracy and referring to market data around 1 January 1991. For council tax, the basis of
measurement for all houses and bungalows is the building’s gross floor area, including wall
thicknesses. This will include bay windows, chimney breasts etc., but will generally exclude
areas with headroom under 1.5metres (e.g. under sloping ceilings in attic rooms).
The basis of measurement for most flats and maisonettes is net floor area with measurements
taken between the wall surfaces of each room (not skirting boards). Bathrooms, WCs and
associated lobbies, as well as connecting corridor areas within a flat would not usually be
measured. As with houses, areas with headroom of less than 1.5 meters will be excluded.
Individual properties might need to have their banding re-considered when:
A house decreases in value because: 1. part of it is demolished, 2. substantial changes
take place in the local area (for example a new road is built nearby), or 3. alterations
have been carried out to make it suitable for use by a person with a physical disability.
The owner starts or stops using part of your home to operate a business, or the balance
between business and domestic use changes.
A home gains a higher value because a previous owner has carried out major
improvements, such as building an extension.
A self-contained unit is built, such as an annex to house an elderly relative.
A house has been split into individual flats, or flats have been merged into one home.
A banding is also done for different kinds of self-contained units. A self-contained unit is a
building or part of a building constructed or adapted to make it capable of forming a separate
unit of living accommodation. This could be, for example, an annexe for an elderly relative,
or adjoining properties knocked through, and occupied as one unit, but retaining essential
facilities of two. Common examples of properties that are identified as self-contained units
are: 1. Annexes, or ‘granny’ flats, often designed and built for elderly relatives, 2.
Accommodation for wardens in student accommodation. 3. Previously separate but adjoining
houses/flats now occupied as one residence, 4. Former servants’ quarters in large houses.
In summary the valuation in UK is had been done implicitly by the government in 1991,hence
the role of the use of 3D information is not clearly identified in UK valuation process. Newly
constructed properties are also assigned a nominal 1991 (2003 for Wales) value and banding.
Also the banding is reconsidered when a property is changed as mentioned. For banding
newly constructed properties and changes in banding the Valuation Office Agency needs
recent information of the property on type, size, age and location. A 2D or 3D model can help
presenting these data to the Valuation Office Agency. Although explained in government
documentation the exact (rules) of the valuation (such as explained in the former section
regarding Turkey) are not explicit and made publicly available. Local authorities set a council
tax rate and value based on the banding of the property.
Next to the banding system for residential properties in the UK the non residential properties
are valued every five year for the business rates. For these business rates the rental value of
the property is valued by the Valuation Office Agency. For these business rates the Valuation
Office Agency not only needs information on newly constructed (non residential) properties
and information on changes, but also information on all properties for the periodical
revaluation. However the 2015 revaluation is postponed to 2017 to save costs.
43
Umit Isikdag, Mike Horhammer, Sisi Zlatanova, Ruud Kathmann and Peter van Oosterom
Semantically Rich 3D Building and Cadastral Models for Valuation
4
th
International Workshop on 3D Cadastres
9-11 November 2014, Dubai, United Arab Emirates
3.3 USA
Property tax in the USA (Wikipedia USA, 2014) has a long history, and was already well
established in most of the then 15 states, by 1796. We will discuss property tax in the US,
with regard to real estate, as opposed to cars or certain business property or inventories. In
contrast to other forms of tax (including property tax on aforementioned non-real-estate), real
estate property tax will generally not cause (unexpected) budget shortfalls – at least in theory.
The process is such, that revenue equals tax levy, except, presumably, for significant
economic, political, or other disruptions, between assessment and payment:
Fair market values are estimated, throughout a respective region. Multiplication with a
local assessment ratio (such as 0.96) yields individual assessed property values v
i
.
(Assessment ratio may vary between categories, such as residential, farming, etc.).
Contests of assessment may lead to “corrections” in individual assessed values v’
i
.
Known required total revenue r and all known corrected assessed values v’
i
(plus
exemptions, credits, etc) allow subsequent derivation of a required local tax rate
(which may also vary between categories, possibly even distinguishing between
inhabited and vacant buildings). This yields assessed tax, for each individual property.
It also yields the required total revenue, apparently quite reliably. There are, of course,
political, economic, and legal constraints: some local rules may limit individual yearly
property tax increases. Similarly, political and economic considerations result in
similar constraints.
Implementation of valuation, assessment, and values of assessment ratio and tax rate vary
significantly across USA counties, cities and school districts, also depending on the legal
framework set up by state legislation.. Local jurisdictions can levy overlapping property taxes
(within potential state regulations). Revenue tends to be used for school districts and other
local expenses. States and the federal government generally do not tax real estate property,
but the resulting income and capital gains.
Despite significant local variations, property taxes are generally based on some measure of
fair market value, multiplied with a local assessment ratio and a tax rate. When a property has
recently been traded between unrelated parties, then that transaction value serves as fair
market value, for some period of time. Beyond that, the fair market value has to be assessed,
to some degree subjectively, by an assessor. Preferential treatment might be given to certain
property categories (such as farms, non-profit organizations, etc.) or businesses the
government would like to specifically attract. Also, fair market value may be determined,
based on actual, or based on optimal use. Residential and farm property tend to be more likely
to be assessed, based on actual use, than some other real estate categories. Many local rules
allow for homestead exemptions, such as exempting the first $50,000 of primary residences
from property tax. Valuation techniques tend to be based on:
Recent sale transaction between unrelated and non-compelled parties.
Otherwise, sales of comparable properties, based on similar:
o Type, use, and size.
o Location.
o Improvements (features, materials, style, amenities, even existence of a fixed
kitchen island, or number of power sockets). Owners may avoid certain forms
of development to limit assessed values. This has been recognized as an issue,
leading to a separate consideration of land and improvements.
o Desirability, proximity to schools.
44 Umit Isikdag, Mike Horhammer, Sisi Zlatanova, Ruud Kathmann and Peter van Oosterom
Semantically Rich 3D Building and Cadastral Models for Valuation
4
th
International Workshop on 3D Cadastres
9-11 November 2014, Dubai, United Arab Emirates
o RRRs. In order to reduce assessed values, owners may sometimes ask to have
rights restricted that they do not plan to exercise, anyway.
o Economic conditions.
Otherwise, original or replacement cost, minus depreciation.
Or, if applicable, income generating ability.
In the USA the valuation to market value and assessment for taxation purposes is (nearly)
always done by using statistical modelling using multiple regressing types of models.
It would be hard to represent local rules and variations, and subjective judgment, in even a
sophisticated 3D building model or cadastre. However, statistical models may yield local
parameters, beyond mere assessment ratio and tax rate. A limited number of common
concepts, plus several local correction factors f
i
may model local variations, successfully.
Applicability of 3D Building Models and 3D Cadastres Due to the many aspects that can
affect assessed values in many USA locales, 3D building models and cadastres seem to be
great potential tools to support the computer assisted appraisal models (CAMA) and
assessment of properties, as well as communication to the public.
Some very detailed aspects, such as wooden floor, number of power sockets, and fixed
kitchen islands, used in the appraisal models appear to require very rich 3D models, with a
combinatorial explosion of complexity. It should be possible, though, to limit the models to
aspects common to many locales, as opposed to local idiosyncrasies. Any aspects not in
common use, any subjective or only loosely defined concepts could be represented as
SPECIAL_CASE_FACTOR or SPECIAL_CASE_OFFSET in various strategic areas of a
global model. A homestead exemption of the first $50,000 of a property value could be
modeled with the same formula as a local rule that only taxes the first $100,000 of
improvements, to reduce sprawl. We may not have to explicitly model all the many different
concepts, individually, by name.
3.4 Germany
Property tax in Germany (Wikipedia Germany, 2014) has been uniformly regulated, since
1938. In the context of the reunification in 1990, property tax in the new states (“east”) has
been adapted and merged into the federal system, with some differences remaining between
old (“west”) and new states.
Property tax in Germany (Grundsteuer) is similar to the equivalent in the US, in many ways.
There is a property value (Einheitswert), multiplied with a factor (Grundsteuermesszahl)
similar to the USA assessment ratio. Multiplied, they yield the Grundsteuermesswert, similar
to the USA assessed value. Multiplied with a tax rate (Hebesatz), they yield the assessed tax
(Jahresgrundsteuer).
Semantically, however, there are differences:
The Einheitswert is not a fair market value, but a federally standardized value proxy.
This is similar to a USA county that would estimate assessed values, based on building
and land square footage, local population density, type, use, and income generating
capabilities, alone. It does not aim to reflect actual market value, and only reflects
relative market value differences between multiple properties, very approximately. A
neighbor A with a property of slightly lower market value than neighbor B might
nevertheless end up paying slightly more in property tax. Large distortions are very
45
Umit Isikdag, Mike Horhammer, Sisi Zlatanova, Ruud Kathmann and Peter van Oosterom
Semantically Rich 3D Building and Cadastral Models for Valuation
4
th
International Workshop on 3D Cadastres
9-11 November 2014, Dubai, United Arab Emirates
unlikely, though, particularly considering local building codes and other restrictions.
When comparing non-neighboring properties in far-apart locations, relative distortions
of Einheitswert compared to market value may increase. This is less relevant, though,
due to the different tax rates in such far-apart locations.
The Grundsteuermesszahl is federally determined, not locally (such as the USA
assessment ratio). This does not limit local flexibility, though, since setting the tax
rate, locally, allows all the flexibility needed. Similar to the assessment ratio, also the
Grundsteuermesszahl varies, depending on property type.
The Hebesatz, similar to the USA local tax rate, is determined, locally, and can vary,
depending on property type. Numerically, both Grundsteuermesszahl (given in ‰) and
Hebesatz tend to have significantly different value ranges than their equivalents in the
US. The concepts are otherwise quite similar, though. The fact that the Einheitswert is
not the real market value and is multiplied with two hard to understand percentages
might make the property tax in Germany less intuitive. Many homeowners may
primarily remember the fairly static amount due, and ignore the complicated
underlying math. For the more technical purpose of modeling property tax, complexity
should be similar to the US, though.
Similar to the USA:
German property tax is considered very predictable revenue, since it is guaranteed by
the property value, and the current owner, personally. In case of sale, the new owner
can also be liable for the property tax the old owner has not paid. The new owner will
thus verify that there is no such remaining balance.
Individual properties can be exempted from property tax, such as to attract business,
protect historic buildings that generate little to no income, etc.
Exceptions similar to homestead exemptions exist.
Local governments receive the revenue of the property tax.
Property tax is determined for land and buildings, separately.
Current use, as well as potential use, and RRRs, can affect property tax. An owner
might request (not necessarily successfully) to further restrict their RRRs, yielding a
lower property tax.
Applicability of 3D Building Models And 3D Cadastres The current property tax in
Germany, despite its similarities to the USA system, would not depend on quite that much
detail in a 3D building model or cadastre. Many aspects, such as wooden floors or granite
countertops have no bearing. Many of the more conventional aspects of 3D models and
cadastres, such as RRR, though, could be very useful in modeling German property tax.
3.5 The Netherlands
For the valuation for market purposes, for instance for sales and other types of real estate
transactions in the Netherlands there is no specific regulations. Certified appraisers working in
this field can use Cadastral information on RRR. For the valuation the appraisers also need
information on object characteristics. They have to collect these characteristics of the object
to be valued themselves. A very limited part of these data can be derived from the Key-
register for buildings and addresses in the Netherlands. However the appraiser is responsible
for the accuracy of the data he is using on building year and area of the property. Therefore
46 Umit Isikdag, Mike Horhammer, Sisi Zlatanova, Ruud Kathmann and Peter van Oosterom
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mostly he collects these characteristics himself, for instance by measuring the property using
construction drawings. Also the certification scheme for certified appraisers is a responsibility
for the market parties involved. There is no official regulation for the skills of the private
certified appraiser.
The valuation and assessment of real estate for government purposes is regulated by the Act
for Real Estate Assessment (in Dutch: "Wet Waardering Onroerende Zaken (WOZ)"
(http://wetten.overheid.nl/BWBR0007119). English translation: http://www.waarderings-
kamer.nl/default.aspx?sec=content&id=1064). The assessed value in the Netherlands is
therefore called "WOZ-value" of a WOZ-object. The WOZ-object is a built or not built real
estate property, a part of a real estate property (when this part is used by a tenant and is a
separate (lockable) unit with all facilities) or a complex of properties (owned by one person
and used as unit by one user).
Since 2007 the valuation of all properties (WOZ-objects) is done every year and on real
market value. For the valuation the appraiser looks back one year, so the assessed value for
the year 2014 is based on the real estate market on 1 January 2013. For all residential
properties the valuation is made using the methods of comparable sales. Because of the
number of properties to be valued (about 7.5 million residential properties and 1 million non
residential properties each year) techniques for mass appraisal are used with computerized
valuation models. For non-residential properties the valuation is based on income approach
(using information on market rents) or cost approach (base on actual investment in building
project of coarse taking into account depreciation for older properties).
The WOZ-value is important because it is the basis for a number of taxes in the Netherlands.
The municipalities levy a real estate tax. For residential property the owner pays around 0,1 to
0,2 % of the assessed value as a yearly tax to the municipality. The rates for non-residential
properties are mostly higher and for non-residential properties the user of the property pays
tax as well (the owner occupier of non residential properties pay twice). But the municipality
can also levy other taxes based on the WOZ-value, for instance a sewer tax). Polderboards in
the Netherlands (other type of local government in the Netherlands that take care for ‘dry feet’
even when a large part of the country is below sealevel) also levy a property tax from the
owner of the property as a percentage of the assessed value. On national level the central
revenue office uses the WOZ-value for levying income tax, inheritance tax, corporation tax
and more.
The municipality is responsible for the valuation and this is checked at national level by the
Council for Real Estate Assessment (in Dutch: ‘Waarderingskamer’). The municipalities (in
2014 403 municipalities) often use the services of companies to perform the actual valuation
or cooperate to be able to have highly specialized staff for the work. A large part of the work
is collecting and updating the data for the valuation models. For collecting and updating data
we distinguish:
Market data. Municipalities get all sales prices out of the national key-register for
cadastral information. Municipalities collect themselves information about properties
on the market (internet advertisements) on rent prices for commercial properties like
offices and shops and building costs of specific properties like schools, hospitals and
industrial sites.
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The legal (and planning) status of the involved properties or in LADM terminology:
the RRRs. The municipality finds the legal information in the key-register for
cadastral information, but because of the regulation in the Act for Real Estate
Assessment primarily information about the owner of the property is important.
Planning information is derived from the municipal zoning maps.
Object characteristics. Most of the information on type, and size of properties,
building years, quality of materials, quality of facilities within the building,
maintenance condition etc. is collected and updated specifically for the valuation and
assessment. Use and updating information on building year and size of property is
often done in connection with the key register on buildings (also a municipal
responsibility) and the key register for large scale base maps. Collecting and updating
information is mostly not done directly in the field, but is done in the office using
recent (yearly) aerial photographs and street view type of images (cyclorama's). The
information in the pictures is transferred into administrative object characteristics as
type of building or grade for maintenance condition, because only these administrative
object characteristics can be used in the automated valuation models.
For change detection automated techniques are used for comparing aerial photographs for
consecutive year or comparing aerial photographs with existing digital maps. In practice
nowadays there is only limited direct use of 2D geometries, mostly because size of property
and type of building can not be derived from these 2D models. However there is an intensive
use of 2D aerial photographs enriched with streetview images. One can imagine that
semantically rich 3D models in which the surface of buildings is shown with picture images,
will not only help to automatically detect comparable building (at comparable locations), but
also help the appraiser updating object characteristics for the valuation models.
Applicability of 3D Building Models and 3D Cadastres Combining the appraisal with 2D
or 3D geometry also can help to convince the owner of the property that the municipality has
made a reliable assessed WOZ-value for his property base on accurate object characteristics.
In the near future, the WOZ-values for residential properties must be publically available in
context of a fair and transparent government. A web-based WOZ-viewer will be introduced,
not only showing the value of a single property, but also the values of the surrounding
properties. In the first phase this will be presented using 2D geometries (user can choose
between map or aerial photographs). But in case of apartment complexes and some other
configurations it can be hard to select a property within a 2D geometry and 3D geometries
may be needed.
3.6 Analysis
From the above valuation cases we learn that current valuation practice are primarily using
administrative data for the valuation models. Models that use 2D or 3D geometries directly
for valuations are not yet implemented in practice. However 2D and 3D models are becoming
more and more important for updating the information within the valuation models and for
presenting valuation results with the underlying data to for instance the owners of properties.
It can be expected that when 3D geometries are available and can object based be combined
with object characteristics a growing number of systems for computer assisted mass appraisal
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will get possibilities to use these characteristics in conjunction with the geometric data on
size, location and comparability.
4. IMPROVE VALUATION POSSIBILITIES IN THE FUTURE
With the realistic expectation that in the near future up-to-date and semantically rich 3D
building models and 3D cadastres will be realized and data accessible via SDI, the future
valuation may become significantly more efficient and flexible. The effect of this would differ
by country, since some valuation/assessment procedures are more resource consuming than
others. On the efficiency side, a uniform (file/database) data source and automated analysis
should clearly offer improvements, compared to currently usually manual information
aggregation and personal judgment, often “in the field”.
Also, it is not clear that assessment would necessarily be solely based on measures or proxies
of market value. There already are many exemptions, separate assessments of land and
improvements, assessment ratios and tax rates that differ by locale, type, and use, all of which
expressly deviate from property tax being proportional to value. Sometimes income
generating ability of either property or owner are taken into account, sometimes not. A retired
owner of a (historic) castle may be more successful pleading for property tax exemption than
the retired owner of merely an above-average house. Clearly, there is an interest in taking
parameters into account that are unrelated to value, but clearly can be modeled in 3D building
models or cadastres. Uniform handling and implementation of such factors is not only fair,
but also allows the government to more effectively achieve the intended policy goals (of
either favoring or disincentivizing various concepts).
New 3D representations should be investigated as well. Typically buildings are represented by
BIM, e.g. Industrial Foundation Classes (IFC) (MSG, 2007)) or CityGML. The two standards
have different concepts, i.e. they represented the building structure from two distinct views:
the constructor (IFC) and the user (CityGML) view. Which model is more appropriate to be
used for property tax is further to be studied in detail. IFC models provide many details but
are still not that commonly used. In contrast, CityGML LOD1 and LOD2 exist for many cities
all over the world. LOD1 and LOD2 however represent only the outer shell of the building
and have no interior information. Ongoing research suggests that outdoor LODs can be
automatically enriched with interior information.
Boeters 2013 has shown in this research that LOD2 can be extended with information about
floors and thickness of the walls and slabs. The research was performed on request of the
Municipality of Rotterdam, the Netherlands. The goal was to compute the internal net area
(i.e. the area that can effectively be used), which is used amongst others also for taxation. The
Dutch standard NEN 2580:2007 (NEN 2580, 2007) and later BAG (Fuld, 2007) provide
guidance how to compute the net internal area. The two documents differ in some of the
specifications, but these differences have been not properly reflected in the registration of
internal net area. To check these values for the entire city of Rotterdam, CityGML LOD2
models were extended automatically to LOD2+ (LOD2 + interior floors). LOD2+ was
reconstructed with knowledge about number of floors (from BAG) and assumptions on the
thickness of walls and floors (related to the year of construction). Figure 2 shows the original
LOD2 and the extended LOD2+. The applied approach was tested for one neighborhood in
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the City of Rotterdam. Although the approach is not very accurate (due to many assumptions
and lack of information), the comparison between the computed LOD2+ and the registered
net internal area, have shown interesting results. For the majority of the buildings the net
internal area was smaller than the registered values available in BAG (73.4 %). The net
internal area from the LoD2+ model was 16% smaller than that registered in BAG. Further
investigations of the results, have clarified that the most of the differences come from the area
under the gable roofs. According to BAG, areas with a roof less than 1,5m have to be
subtracted from the net internal area (Boeters 2013).
This research has clearly shown that 3D representations can support mass computation of net
area and consequently facilitate taxations of properties. The representations should not
necessarily be very detailed, which allows for uniform automatic approaches.
Figure 2: CityGML LOD2 and CityGML LOD+
One might argue that 3D building models and cadastres for property tax excel at taking
objective factors into account, but devalue the art of personal judgment. This is not
necessarily true, since subjective factors or offsets could easily be modeled (though they may
reduce automation). But one might also object that factors that can be formalized may
ultimately enjoy higher legitimacy, anyway.
5. CONCLUSION
Despite the fact that analyzed valuation cases in the selected countries are primarily using
administrative data for the valuation models, it was argued in this paper that models that use
2D or 3D geometries directly for valuations would have some significant benefits. However,
for fair annual valuations, it is clear that the used models and data need to be up-to-date.
There is the debatable question of who should be allowed to update authoritative 3D building
models and cadastres, based on which processes, and yielding which level of accuracy or
reliability. Who should pay for it? Would volunteered data sets be included? Digital
signatures authenticating each update may be useful. But in general we can say that in the
future, owners of property, but in general "the crowd" will play a greater role in keeping
information up to date and this can also help updating functional 3D data systems.
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It might also be possible to assign levels of confidence, for each update. Any automated
assessment analysis on top of such data may be able to derive an overall level of confidence
for the resulting assessment. Prior to changing the formula to derive property taxes, officials
could first query, what level of confidence is currently assigned to the existing data the new
formula would be based on. Instant and virtually cost-free analysis of feasibility can
presumably only benefit policy decisions.
REFERENCES
Hasan Bal .(Ed.) (2014), SPK Gayrimenkul-Konut Değerleme Uzmanlığı, Gazi Kitapevi,
2014.
Roeland Boeters, 2013, Automatic Generation of CityGML LOD2 models with interiors and
its suitability for net internal area determination, MSc Thesis Geomatics, Delft University of
Technology, p. 138,
http://www.gdmc.nl/publications/2013/Automatic_enhancement_CityGML.pdf.
Fatih Döner, Rod Thompson, Jantien Stoter, Christiaan Lemmen, Hendrik Ploeger, Peter van
Oosterom and Sisi Zlatanova (2011). Solutions for 4D cadastre - with a case study on utility
networks In: International Journal of Geographical Information Science, Volume 25, 7, 2011,
pp. 1173-1189.
Marthe Fuld. Key Registers for Addresses and Buildings. Presentation, September 2007,
http://wiki.geonovum.nl/images/BAG_EN.pdf.
Gerhard Gröger and Lutz Plümer, 2012, CityGML Interoperable semantic 3D city models,
ISPRS Journal of Photogrammetry and Remote Sensing, 71:12–33, July 2012.
MSG 2007, Industry Foundation Classes, IFC2x Edition 3, Technical Corrigendum 1, Online
documentation, http://www.buildingsmart-tech.org/ifc/IFC2x3/TC1/html/index.htm.
Umit Isikdag and Jason Underwood (2010). A Synopsis of the Handbook of Research on
Building Information Modeling, In Proceedings of CIB 2010 World Building Congress
http://www.cib2010.com.
Ruud M. Kathmann and Marco Kuijper (2014). Cooperation between taxpayers and
municipalities for valuation purposes, Proceeding of FIG conference 2014.
Christiaan Lemmen, Peter van Oosterom, Rod Thompson, João P. Hespanha and Harry
Uitermark (2010). The Modelling of Spatial Units (Parcels) in the Land Administration
Domain Model (LADM). In: Proceedings of the XXIV FIG International Congress 2010,
April 2010, Sydney, 28 p.
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NEN 2580 (2007), Oppervlakten en inhouden van gebouwen Termen, definities en
bepalingsmethoden, http://www.nen.nl/NEN-Shop-2/Standard/NEN-25802007-nl.htm (in
Dutch).
ISO19215-1:2004 (2004). Geographic information - Simple feature access - Part 1: Common
architecture.
http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=40114.
ISO 19152:2012 (2012). Geographic information - Land Administration Domain Model
(LADM), version 1 December 2012.
OGC (2012) OGC City Geography Markup Language (CityGML) Encoding Standard,
Available online http://www.opengeospatial.org/standards/citygml.
VOA (2014). Understanding your Council Tax Banding, Valuation Office Agency Report.
Available from:
http://www.voa.gov.uk/corporate/_downloads/pdf/VO7858_understanding_ct.pdf [Accessed,
10-09-2014].
Wikipedia USA (2014). http://en.wikipedia.org/wiki/Property_tax_in_the_United_States.
Wikipedia Germany (2014). http://de.wikipedia.org/wiki/Grundsteuer_%28Deutschland%29.
BIOGRAPHICAL NOTES
Umit Isikdag has his MSc in Civil Engineering and PhD (from the University of Salford) in
Construction Information Technology with his work on integration of BIM with 3D GIS. His
research interests include BIM / IFC, 3D GIS, Internet of Things, RESTful Architectures,
BIM 2.0, and Spatial Web Services. He is lecturing in Beykent University Dept. of .Civil
Engineering and actively involved in the organization of 3D GeoInfo and GeoAdvances
Conferences, editorship of International Journal of 3D Information Modeling, and also
serving as the Secretary of ISPRS WG II/2.
Mike Horhammer received his Diploma in Computer Science, from RWTH Aachen,
Germany, in 96, and his Ph.D. in Computer Science, from UC Santa Barbara, in 99. He has
been working in Oracle Spatial, since 99, currently on 3D aspects of point clouds, TINs and
city models, as well as coordinate systems.
Sisi Zlatanova is an associate professor and leading the theme group ‘Geo-information for
Crisis Response’ at the GIS Technology Section, Department OTB, Faculty of Architecture
and the Built Environment, Delft University of Technology, the Netherlands. She has
graduated as a surveyor at the University of Architecture, Civil Engineering and Geodesy,
Sofia, Bulgaria in 1983 and has obtained her PhD degree on ‘3D GIS for urban modelling’ at
the Graz University of Technology, Graz, Austria in 2000. She is teaching several courses
related to 3D GIS, 3D databases and their application for disaster management within TU
52 Umit Isikdag, Mike Horhammer, Sisi Zlatanova, Ruud Kathmann and Peter van Oosterom
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Delft, the University of Venice (2007, 2008). Her research interests are in 3D geo-information
and their applications for emergency management (especially flood management). She is
chair and co-chair of several conferences among which Gi4DM, 3Dgeoinfo and UDMS.
Ruud Kathmann has studied geodetic engineering at the Delft University of Technology and
graduated in 1985. He is a member of the management team of the Dutch Council for Real
Estate Assessment. From this position Ruud is closely involved to the development of the
System of Base Registers. In the Netherlands Ruud is considered to be one of the leading
specialists on the areas of geo-information, mass-appraisal and e-government.
Peter van Oosterom obtained an MSc in Technical Computer Science in 1985 from Delft
University of Technology, the Netherlands. In 1990 he received a PhD from Leiden
University. From 1985 until 1995 he worked at the TNO-FEL laboratory in The Hague. From
1995 until 2000 he was senior information manager at the Dutch Cadastre, where he was
involved in the renewal of the Cadastral (Geographic) database. Since 2000, he is professor at
the Delft University of Technology, and head of the ‘GIS Technology’ Section, Department
OTB, Faculty of Architecture and the Built Environment, Delft University of Technology, the
Netherlands. He is the current chair of the FIG Working Group on ‘3D Cadastres’.
CONTACTS
Umit Isikdag
Beykent Üniversitesi Ayazaga Kampüsü
Sarıyer/İstanbul
TURKEY
Tel.: +90 536 434 77 37
E-mail: uisikdag@gmail.com
Website: http://www.isikdag.com
Mike Horhammer
Oracle
1 Oracle Drive
Nashua NH 03062
USA
E-mail: Mike.Horhammer@oracle.com
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Umit Isikdag, Mike Horhammer, Sisi Zlatanova, Ruud Kathmann and Peter van Oosterom
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Sisi Zlatanova
Delft University of Technology
Faculty of Architecture and the Built Environment
Department OTB
GIS Technology Section
P.O. Box 5030
2600 GA Delft
THE NETHERLANDS
Tel.: +31 15 2782714
Fax: +31 15 2784422
E-mail: S.Zlatanova@tudelft.nl
Website: http://www.gdmc.nl
Ruud Kathmann
Netherlands Council for Real Estate Assessment
P.O. Box 93210
2509 AE The Hague
THE NETHERLANDS
Tel.: +31 70 311 0555
Fax: + 31 70 311 0570
E-mail: r.kathmann@waarderingskamer.nl
Website: www.waarderingskamer.nl
Peter van Oosterom
Delft University of Technology
Faculty of Architecture and the Built Environment
Department OTB
GIS Technology Section
P.O. Box 5030
2600 GA Delft
THE NETHERLANDS
Tel.: +31 15 2786950
E-mail: P.J.M.vanOosterom@tudelft.nl
Website: http://www.gdmc.nl
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... Furthermore, many publications focusing on 3D cadaster, land administration and taxation point out to the new possibilities for real estate valuation using the benefits of BIM technologies, especially through application and/or extension of land administration domain model (LADM) as an international standard for land administration (Atazadeh et al., 2017a, Atazadeh et al., 2017b, Isikdag et al., 2014, Kara et al., 2021a, Kara et al., 2021b, Kara et al., 2020, Isikdag et al., 2015, Ying et al., 2017, Guntel and Aydinoglu, 2021, Aien, 2013, Li et al., 2016, Paasch and Paulsson, 2021, Wu et al., 2021, Einali et al., 2022, Atazadeh et al., 2016, (FIG), 2018, Kara et al., 2022, Radulovi c et al., 2017, Almeida et al., 2013. ...
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This paper presents in detail the legislation and regulation related to the use and ownership of building complexes with multiple units (apartments, condominiums) in Saudi Arabia for the 3D registration of the legal spaces. The 3D Land Administration Domain Model (LADM)country profile for Saudi Arabia must be able to represent the identified concepts for multi-owner buildings. Today, there is a trend to directly design these buildings in 3D. Within the spatial development lifecycle thinking, this design will be reused via Building Information Modelling (BIM)/ Industry Foundation Class (IFC) encodings in the subsequent phases, such as, obtaining permits, financing, constructing, etc. However, in order to support the next step, the cadastral registration, we present, at this paper, a mapping from the BIM/IFC to the LADM, both at conceptual modelling and at the level of the individual units with their geometry and topology. This mapping requires that the BIM/IFC file contains sufficient information to identify the different spaces being part of a property. Three different main type of spaces are identified: private part, common part, and exclusive common part. A single property may contain multiple disconnected components, such as the main apartment, the storage in the basement, and a car park. In turn, a component, such as the main apartment, may contain multiple connected spaces, i.e. the various rooms of the main apartment. In addition to mapping the concepts at class level from IFC to LADM, we also extract rules for treating the spaces of various types of walls, slabs, roofs, and constructive elements, such as foundation and pillars. The presented approach is tested with a real-world example IFC file, identifying the issues to be improved, i.e. guidelines for the Architecture, Engineering and Construction (AEC) sector to produce IFC file which can be more easy used as input for 3D Land Administration with minimal manual interventions. This research bridges the gap between the project-oriented world of the AEC sector (with BIM/IFC files) and the legal registration as described through the ISO 19152. Though many of the presented findings are based on the legislation and case study in Saudi Arabia, we have the rather strong impression, that these findings will not be very different in other countries.
... Similarly, high-rise and multi-storeys have individual properties which must be insured at a relevantly high level of premium. The role of 3D spatial database could be influential in getting more credit against the mortgaged property because of higher level of accuracy of space volume for the property [42,43]. The 3D spatial database can also raise the premium for higher volume of space. ...
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... Traditional cadastral systems generally provide two-dimensional (2D) boundaries of property units and legal information over them, whereas today's valuation practices also require three-dimensional (3D) spatial units (e.g. building units) together with the detailed physical, locational and environmental characteristics (Isikdag et al., 2014(Isikdag et al., , 2015Atazadeh et al., 2017). It is also noted that the basic registration unit of cadastral systems (e.g. ...
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Spatial data in a Land Administration (LA) establish a fundamental geospatial data theme (see UN GGIM, 2018) and the integrated geospatial information framework for any Spatial Data Infrastructure (SDI). Domain-specific standards, an integral component of the SDI, play an essential role to represent the semantics of domains, specify links between distributed registries and databases, and stimulate the development and implementation for Land Administration Systems (LAS). As an international descriptive standard providing an abstract conceptual schema, the ISO 19152:2012 Land Administration Domain Model (LADM) has been used and is being used as a reference for the implementation of LAS. Various approaches have been used for the LADM implementation that includes elaborating (via a country profile) and realizing a technical model suitable for the implementation (van Oosterom and Lemmen, 2015). LADM focuses on a specific function of LA that is interested in Rights, Responsibilities and Restrictions (RRR) affecting land, and the geometrical components thereof. The land value function of LA is considered outside the scope in the first edition. Recently, for extending the flexible and modular basis of the LADM, a valuation information model is developed for the specification of valuation information maintained by public authorities. It identifies the links between property valuation and the other LA registries and databases (e.g., cadastre, land registry, building and dwelling registries) that may enable interoperability across systems. The conceptual schema of the model provides a common basis to direct the development of local and national valuation databases and information technology products and services, following an approach similar to the LADM implementation. The proposed LADM Valuation Information Model is on the agenda of the development of the second edition of LADM within ISO/TC211. The operability of the newly proposed conceptual model needs to be evaluated through technical implementation. This paper describes the development of a prototype for the implementation of the LADM Valuation Information Model and assesses its operability through a case study for Turkey. The primary aim of the paper is to test the capabilities of the LADM Valuation Information Model using the required and produced data in recurrent valuation processes, but not to build a specific information management system for Turkey. As the implementation of a LADM compliant prototype initially requires the development of a country profile at conceptual level, methodologies applied for LADM profile development are examined and then a Turkish LADM Valuation Information Model country profile is proposed using the Conceptual Schema Languages (CSL) of the Unified Modelling Language (UML) and INTERLIS. INTERLIS is a formal language as well as a set of software tools that support LADM implementations. Subsequently, approaches and tools used in the LADM implementation are investigated and utilized for the automated transformations from the country profile to several technical models. In this context, the article presents the experiences gained during the implementations. Moreover, strategies for implementing and managing property valuation information more efficiently (e.g. bi-temporal aspects of valuation information management) are also studied and applied to the implementation. The generated technical models are then populated with sample datasets related to recurrent property valuation including the geometries of valuation units, as well as valuation information covering several years. The developed prototype is then tested through a number of queries to assess whether the LADM Valuation Information Model fulfils information management needs of recurrent valuations. The main contribution of this paper is to provide a holistic approach on how to develop an LADM conformant prototype for managing property valuation information.
... The disapproval has mounted against the current 2D-based practice of recording 3D ownership RRRs of MOBs (Isikdag, Horhammer, Zlatanova, Kathmann, & Van Oosterom, 2014). It has been shown how the abstracted 2D projection of 3D RRRs is likely to reach different concepts over the same set of diagrams in the cadastral plans. ...
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There are different processes in 3D urban land administration in which spatial analysis plays an underpinning role. Among 3D data models, Industry Foundation Class (IFC) provides the potential capabilities for modelling legal and physical dimensions of urban properties. However, performing spatial analysis using IFC files cannot address the on-demand spatial analysis requirements of 3D urban land administration. In response to this limitation, 3D data needs to be stored in a spatial database to enable spatial analyses required by different stakeholders. Therefore, in this paper, by considering spatial analysis requirements in 3D-enabled urban land administration, an IFC-based database schema is designed. Moreover, a methodology for transforming Building Information Modelling (BIM) data into the proposed schema is provided. This methodology includes seven steps: designing the architectural model and adding legal data, georeferencing, IFC data validation and cleaning, mapping process, database data validation and cleaning, spatial analysis, and visualisation. To demonstrate the feasibility of the proposed database, three datasets are implemented in the database. Moreover, a new method for modelling legal spaces with oblique structures and two applications of spatial analysis in 3D urban land administration are provided.
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Key Registers for Addresses and Buildings. Presentation
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Automatic Generation of CityGML LOD2 models with interiors and its suitability for net internal area determination
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Cooperation between taxpayers and municipalities for valuation purposes, Proceeding of FIG conference
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Understanding your Council Tax Banding, Valuation Office Agency Report Available from: http://www.voa.gov.uk/corporate
VOA (2014). Understanding your Council Tax Banding, Valuation Office Agency Report. Available from: http://www.voa.gov.uk/corporate/_downloads/pdf/VO7858_understanding_ct.pdf [Accessed, 10-09-2014].
Geographic information -Land Administration Domain Model (LADM), version 1
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