# Fabio CrosillaUniversity of Udine | UNIUD · Polytechnic Department of Engineering and Architecture

Fabio Crosilla

Professor

Scientific coordinator of CISM-APT section.

## About

104

Publications

73,384

Reads

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1,190

Citations

Introduction

Fabio Crosilla is a Senior Professor of Photogrammetry, Surveying and Digital Mapping. He was Alexander von Humboldt Foundation fellow at the Geodetic Institute of Stuttgart University. Author of 3 patents and more than 220 publications, he was until 2014 the Italian Prime Delegate in the European Spatial Data Research network (EuroSDR). He is currently scientific coordinator of the CISM “Advanced Professional Training“ activities.

Additional affiliations

January 2016 - April 2016

November 2011 - April 2016

## Publications

Publications (104)

Make cities and human settlements inclusive, safe, resilient and sustainable is one of the Sustainable Development Goals drawn by the United Nations. To support renovation projects, a first essential step is to gain an updated and precise knowledge of indoor and outdoor public spaces and urban areas, which requires accurate and fast mapping systems...

In recent years, portable Mobile Mapping Systems (MMSs) are emerging as valuable survey instruments for fast and efficient mapping of both internal and external environments. The aim of this work is to assess the performance of a commercial handheld MMS, Gexcel HERON Lite, in two different outdoor applications. The first is the mapping of a large b...

Fifty years have already passed away from the production start-up of the regional technical map of the Italian Friuli Venezia Giulia region. On this occasion, the part of the new regional topographic database (DBT), relating to the Trieste province, is now available. This is a new digital product that represents a significant technological evolutio...

Virtual assembly is an essential method to increase efficiency and to identify potential issues of the assembly process in several manufacturing fields, as for instance robotized assembly. The paper presents a novel procedure based on Affine Procrustes Analysis for the Virtual Trial Assembly (VTA) of large-size elements. This approach to virtual as...

Point cloud classification is one of the most important and time-consuming stages of airborne LiDAR (Light Detection and Ranging) data processing, playing a key role in the generation of cartographic products. This paper describes an innovative algorithm to perform LiDAR point-cloud classification, which relies on Convolutional Neural Networks (CNN...

The EOPA and GPA models, described in the previous chapters, can be further extended by substituting the isotropic scale factor c with an anisotropic scaling characterized by a diagonal matrix \(\varvec{\Gamma }\) of different scale factors.

The terms Procrustes Analysis and Procrustes Techniques are referred to a set of least squares mathematical models used to perform transformations among corresponding points belonging to a generic k-dimensional space, in order to satisfy their maximum agreement.

The main peculiarity of the problem treated in this chapter is given by the fact that \(m > 2\) matrix configurations are simultaneously considered.

As shown in the previous chapters, given a matrix \(\mathbf {A}\) (origin) and a matrix \(\mathbf {B}\) (destination), containing the coordinates of p-points in \(\mathbb {R}^k\), classical least squares (LS) Procrustes solutions find the transformation parameters between the two point sets assuming that all random errors are confined to the destin...

This chapter introduces the basic concepts of the automatic 3D surveying by means of laser scanning techniques, a methodology developed less than 20 years ago (see, e.g., Boehler et al. 2002) thanks to the technological improvement of the topographical instrumentations, in particular in the movement and in the electronical components. The main topi...

This chapter introduces the basic geometric concepts of multi-view geometry in computer vision, an important and well-studied part of computer vision, as testified by the wealth of useful results reported in comprehensive monographs (Faugeras 1993; Hartley and Zisserman 2003; Faugeras and Luong 2001).

Photogrammetric computer vision techniques and laser scanning systems can directly provide 3D models of real objects by automatically or selectively sampling the positions of a set of representative surface points. Depending on the dimension and on the shape complexity of the geometric entity under study, its complete survey often requires a multip...

As extensively shown in the previous chapters, Procrustes Analysis allows to easily perform transformations among corresponding point coordinates belonging to a generic k-dimensional space and it is therefore suited to solve problems encountered in geodesy, photogrammetric computer vision, and laser scanning.

This book gives a comprehensive view of the developed procrustes models, including the isotropic, the generalized and the anisotropic variants. These represent original tools to perform, among others, the bundle block adjustment and the global registration of multiple 3D LiDAR point clouds. Moreover, the book also reports the recently derived total...

This work reviews the anisotropic row-scaling variant of the Procrustes analysis algorithms applied to develop new analytical tools for solving classical photogrammetric Computer Vision problems. In Garro et al. (Solving the pnp problem with anisotropic orthogonal procrustes analysis, 2012) the anisotropic row-scaling Procrustes analysis was first...

This paper addresses the problem of 3D building reconstruction from thermal infrared (TIR) images. We show that a commercial Computer Vision software can be used to automatically orient sequences of TIR images taken from an Unmanned Aerial Vehicle (UAV) and to generate 3D point clouds, without requiring any GNSS/INS data about position and attitude...

This letter presents a novel total least squares (TLS) solution of the anisotropic row-scaling Procrustes problem. The ordinary LS Procrustes approach finds the transformation parameters between origin and destination sets of observations minimizing errors affecting only the destination one. In this letter, we introduce the errors-in-variables mode...

In a recent paper (Fusiello and Crosilla, 2015) a Procrustean formulation of the bundle block adjustment has been presented, with
a solution based on alternating least squares. This paper improves on it in two respects: it introduces a faster iterative scheme that
minimizes the same cost function, thereby achieving the same accuracy, and makes the...

In a recent paper (Fusiello and Crosilla, 2015) a Procrustean formulation of the bundle block adjustment has been presented, with a solution based on alternating least squares. This paper improves on it in two respects: it introduces a faster iterative scheme that minimizes the same cost function, thereby achieving the same accuracy, and makes the...

Nowadays, high resolution aerial images are widely available thanks to the diffusion of advanced technologies such as UAVs (Unmanned Aerial Vehicles) and new satellite missions. Although these developments offer new opportunities for accurate land use analysis and change detection, cloud and terrain shadows actually limit benefits and possibilities...

In this paper we formulate the point-line registration problem, which generalizes absolute orientation to pointline matching, in terms of an instance of the orthogonal Procrustes problem, and derive its solution. The same formulation solves the Non-Perspective-n-Point camera pose problem, which in turn generalizes exterior orientation to non-centra...

The paper proposes a procedure based on Kohonen’s Self Organizing Maps (SOMs) to perform the unsupervised classification of raw full-waveform airborne LIDAR (Light Detection and Ranging) data, without the need of extracting features from them, that is without any preprocessing. The proposed algorithm allows the classification of points into three c...

The TS (Turin Shroud) is a linen cloth which enveloped the dead body of a tortured and crucified man that is believed by many to be the burial cloth of Jesus Christ. The linen fabric has been radiocarbon dated in 1988 to the Middle Age but a recent robust statistical analysis shows that the resulting age appears flawed by a systematic effect. The p...

The paper presents a new analytical tool to solve the classical photogrammetric bundle block adjustment. The analytical model is based on the generalized extension of the anisotropic row-scaling Procrustes analysis, that has been recently proposed by the same authors to solve the image exterior orientation problem. The main advantage of the method...

The recognition of vegetation by the analysis of very high resolution (VHR) aerial images provides meaningful information about environmental features; nevertheless, VHR images frequently contain shadows that generate significant problems for the classification of the image components and for the extraction of the needed information.
The aim of th...

The physical trial assembly of a complex steel structure is very expensive in terms of time, costs and logistics. For this reason, the trial assembly of the structure in a virtual way, starting ideally from the data contained in the structure BIM, represents a worthwhile alternative to the physical one.
In this paper an innovative method for the vi...

A new procedure supporting filtering and classification of LiDAR data based on both elevation and intensity analysis is introduced and validated. After a preliminary analysis to avoid the trivial classification of homogeneous datasets, a non-parametric estimation of the probability density function is computed for both elevation and intensity data...

The twelve results from the 1988 radio carbon dating of the Shroud of Turin show surprising heterogeneity. We try to explain this lack of homogeneity by regression on spatial coordinates. However, although the locations of the samples sent to the three laboratories involved are known, the locations of the 12 subsamples within these samples are not....

The paper presents a robust version of a recent anisotropic orthogonal Procrustes algorithm that has been proposed to solve the socalled
camera exterior orientation problem in computer vision and photogrammetry. In order to identify outliers, that are common in
visual data, we propose an algorithm based on Least Median of Squares to detect a minima...

In this paper we formulate the Perspective-n-Point (a.k.a. exterior orientation) problem in terms of an instance of the an isotropic orthogonal Procrustes problem, and derive its solution. Experiments with synthetic and real data demonstrate that our method reaches the best trade-off between speed and accuracy. The MATLAB code reported in the paper...

The point cloud alignment problem has always attracted the interest of the researchers. Two are the procedures usually applied for the close range surveys: the ICP method with all its variants, and the method based on the use of tie points identified by reflecting targets properly located on the overlapping part of two range images. The two methods...

Surveying complex shapes or very large entities by laser scanners often requires the registration of a sufficient number of partial 3-D range images in order to completely reproduce the model of the real object. If redundancy exists among the partial models composing the measured entity, a global adjustment of the model components improves the fina...

The paper deals with the terrestrial laser scanning survey of the Aquileia basilica, one of the most significant monuments of the Italian Romanic architecture, the religious centre of a small town in North-East Italy famous for its roman archaeological ruins. The laser data have been acquired with a Riegl LMS Z360i system integrated with a Nikon D1...

The paper reports two analytical methods capable to reliably perform the simultaneous global registration of non static 3D LiDAR point clouds, and investigates their applicability by analysing the results of some preliminary numerical examples. The first method, proposed by Xiao (2005), and Xiao et al. (2006), apply a direct SVD factorisation to no...

The paper deals with a new sequential procedure to perform unsupervised LIDAR points classification by iteratively studying skewness and kurtosis for elevation and intensity point distribution values. After a preliminary local shape analysis of elevation and intensity point distributions, carried out from the original discrete frequencies by a non...

Da recenti congressi europei è emersa la necessità, per il catasto ed in genere per le organizzazioni di registrazione di beni immobili, di fornire dei servizi all’avanguardia al mercato informativo dei beni immobili in un ambiente di tipo e-government, contemporaneamente cooperando alla realizzazione delle infrastrutture di dati spaziali sia nazio...

The paper describes a new statistical tool named ICS (Invariant Coordinate Selection), recently published in the literature (Tyler et al. 2009). The statistical tool properties and the possible applications for the study of multivariate data are then analyzed. The method, implemented in the R open-source software, allows at first to highlight the o...

In a recent paper Crosilla, Visintini and Sepic (2007) a mixed procedure for the automatic vol- umetric primitives classication and segmentation of 3D spatial objects, surveyed with very high density laser scanning range measurements, was proposed. The procedure consists of three phases: rst, a Taylor expansion is applied for each sampled point, co...

The twelve results from the 1988 radio carbon dating of the Shroud of Turin show surprising heterogeneity. We try to explain this lack of homogeneity by regression on spatial coordinates. However, although the locations of the samples sent to the three laboratories involved are known, the locations of the 12 subsamples within these samples are not....

In this paper we propose a novel approach to cope with the problem of global registration of multiple point clouds, where point correspondences and view order are unknown. The method iteratively minimizes a cost function consid-ering all the views simultaneously. The proposed solu-tion takes advantage of the well-known Generalized Pro-crustes Analy...

Using the 12 published results from the 1988 radiocarbon dating of the TS (Turin Shroud), a robust statistical analysis has been performed in order to test the conclusion by Damon et al. (1998) that the TS is mediaeval. The 12 datings, furnished by the three laboratories, show a lack of homogeneity. We used the partial information about the locatio...

When ordering LiDAR data, LiDAR point density per
surface unit is important information with decisive
influence on the price of the LiDAR survey. The
paper first deals with the theoretical calculation of
the minimum LiDAR point density, necessary for
the acquisition of topographic data of the largest
scales. For this purpose the sampling theorem is...

When ordering LiDAR data, LiDAR point density per surface unit is important information with decisive influence on the price of the LiDAR survey. The paper first deals with the theoretical calculation of the minimum LiDAR point density, necessary for the acquisition of topographic data of the largest scales. For this purpose the sampling theorem is...

Although various rigorous lidar error models already exist and examples of a-posteriori studies of lidar data accuracies verified with field-work can be found in the literature, a simple measure to define a-priori error sizes is not available. In this paper, the lidar error contributions
are described in detail: the basic systematic error sources,...

Dealing with a procedure for the automatic classification of laser point clouds based on surface curvature values, one of
the most critical aspects is the correct interpretation of the estimated results. This care is required since the measurements
are characterised by errors of different kind, and simplified analytical models are applied to estima...

In this paper we explore the potential of LiDAR to distinguish between principal forest typology of alpine latitudes surveyed in leaf-on conditions. To this aim, a complete processing chain was developed, starting with the point cloud as input data and ending with derived curvature value of single trees useful for species classification. First, the...

One of the critical aspects of the curvature based classification of spatial objects from laser point clouds is the correct interpretation of the results. This is due to the fact that measurements are characterized by errors and that simplified analytical models are applied to estimate the differential terms used to compute the object surface curva...

This paper proposes a statistical procedure for the automatic volumetric primitives classification and segmentation of 3D objects surveyed with high density laser scanning range measurements. The procedure is carried out in three main phases: first, a Taylor’s expansion nonparametric model is applied to study the differential local properties of th...

The paper deals with the registration and modelling of terrestrial laser point clouds. For both problems a non parametric regression is suitably exploited, whose unknowns are the function values and the partial derivatives of a second order Taylor's expansion estimated for a certain number of surface points. These allow to directly estimate local c...

The improvement of laser scanning as a proficient technology to better understand the complexity of the forest has recently allowed the detection of the forestry parameters at tree level. From a forest inventory point of view, however, a common use of such technology is related to the accuracy that can be obtained if vast and differently composed f...

Amethod,to automatically detect the tree crowns shape,is presented,in this paper. The study ,site is located in some,mountainous parts of Friuli Venezia Giulia characterized by coniferous, mixed and broad-leaved forests with different population densities. The method, developed in an open source environment, is based on mathematical morphology oper...

One drawback of Procrustes Analysis is the lack of robustness. To overcome this limitation a procedure that applies the Generalised
Procrustes methods, by way of a progressive sequence inspired to the “forward search”, was developed. Starting from an initial
centroid, defined by the partial point configuration satisfying the LMS principle, this is...

FOREWORD This paper has been written in honour of the lamented Raymond Rogers who first proposed this work and dedicated many hours of his life to improve this collection of information; he wrote: " No matter what the truth is about the Shroud, it is a fascinating study. It can be studied according to the rigorous Scientific Method, and it is too b...

This paper deals with the various aspects of the Gorizia downtown (Italy) 3D virtual model production obtained by a suitable integration of laser and imaging data, both acquired either by means of a helicopter and a terrestrial surveying. An aerial high-density (15 points/m 2) laser surveying was achieved with an Optech ALTM 3033 system for an area...

Airborne laser scanning can be employed today for the production of large scale maps and the creation of detailed 3D city models. For this purpose, several solutions have been proposed, also available in commercial software, to make easier and semi-automated the extraction and the geometric modeling of buildings from LIDaR data. As a consequence, w...

Riassunto: L'articolo illustra una tecnica di filtraggio e classificazione dei dati laser scan di natura geodetica mediante l'applicazione della "forward search", una procedura robusta di analisi dei residui della stima ML di un modello autoregressivo SAR, introdotta in letteratura per l'identificazione di outliers e di dati non stazionari. Per la...

Riassunto * Alcune porzioni significative della cartografia catastale hanno subito nel tempo un deterioramento geometrico, variamente distribuito e imputabile a molteplici fattori, evidenziato dal raffronto con la realtà odierna e con altri prodotti cartografici recenti. Nel contempo si è accumulata una consistente banca dati di elementi cartografi...

The paper proposes a segmentation procedure inspired to a robust LIDaR filtering data method recently introduced by the authors. The method is based on the application of a Simultaneous AutoRegressive (SAR) model for describing a trend surface and of an iterative Forward Search (FS) algorithm to detect clusters of non-stationary data. The procedure...

This paper proposes a new filtering method of non-ground measurements from airborne LIDAR data through a Simultaneous AutoRegressive (SAR) analytical model and exploiting a Forward Search (FS) algorithm (Atkinson and Riani, 2000, Cerioli and Riani, 2003), a newly developed tool for robust regression analysis and robust estimation of location and sh...

Ordinary least squares (OLS) similarity transformations are often used in practice to perform datum conversions in a wide spectrum of geodetic and photogrammetric problems.
Traditionally, the estimation of the unknown parameters is computed by solving a non linear transformation model, build on a set of correspondence point coordinates known in bot...

Procrustes analysis is a well known technique to provide least squares matching of two or more factor loading matrices or for the multidimensional rotation and scaling of different matrix configurations. Applied at first as a useful tool in factor analysis, today it has become a popular method of shape analysis (Goodall 1991, Dryden and Mardia 1998...

Referring to the current Italian cadastral map updating system, the paper describes an innovative analytical method to perform the general adjustment of the fiducial point network, and the optimal conformal insertion of new surveyed cadastral parcels into an already existing digital map. Working on the surveyors' data files containing the distance...

The paper reviews at first some aspects of the generalised Procrustes analysis (GP) and outlines the analogies with the block adjustment by independent models. On this basis, an innovative solution of the block adjustment problem by Procrustes algorithms and the related computer program implementation are presented and discussed.The main advantage...

An innovative solution of the global multidimensional registration
problem for a set of partial object models is introduced and explained.
The method, based on the classical tie-point concept, is capable to
directly and optimally align models indefinitely rotated, translated and
scaled. The pre-registration is carried out in an automatic way withou...

The purpose of this research is to present a series of automatic methods which improve the quality of DTM with reference to both reliability and precision. These methods consist essentially in determining the possible presence of significant blunders (outliers) and morphological discontinuities (breaklines) of the measures, and the choice of the nu...

This paper describes an original method to determine the external orientation of a digital sensor located on a moving vehicle using exclusively the points of an already existing numerical cartography; the method is alternative to the one largely applied based on the use of satellite and inertial positioning systems. For solving the orientation pare...

The book contains 31 papers on different fields of application and the problems of modelling and organizing data in structures, the processing techniques of GIS data for queries to the system and the so-called Dynamic GIS have been reported in detail. A final paper on Computer Graphics principles is included. Its contents can be ideally collected i...

This paper presents a method for testing the data quality of a G.I.S. making use of the Wilcoxon test. Accuracy assessment procedures based on statistical hypothesis tests are considered first, then the Wilcxon test is presented and a power formula is discussed. This expression needs the estimation of two parameters, obtained by the bootstrap. The...

This paper describes a procedure, based on non-parametric statistics, for testing the data quality of a G.I.S. The procedure compares the contents of a database with a sample of control values captured on field and tests the hypothesis of no difference between the two samples, by the application of the Wilcoxon rank-sum test. The alternative hypoth...

When pattern recognition is used for technical or cartographic images, it is usually believed that the first step to perform is vectorisation. This approach leads to many inconveniences, because it seems to ignore that there exist three distinct layers, namely lines symbols, patterns. For each of these layers the optimal procedures and parameters m...

The paper deals with a new approach and the consequent technique to perform the analysis of a GPS network where undifferenced beat phase observation equations are considered. From the results of the analysis an original method to construct an ideal dispersion matrix is proposed. Such a matrix is constructed only for those estimable functions of the...

It is shown that also in a rank deficient Gauss-Markov model higher weights of the observations automatically improve the
precision of the estimated parameters as long as they are computed in thesame datum. However, the amount of improvement in terms of the trace of the dispersion matrix isminimum for the so-called “free datum” which corresponds to...

The paper deals with the control measurements taken at the Caneva (PN) network in three different epochs and the strain field parameters derived from the displacements of the net points. After a brief description of the measurements taken, of the adjustment model and of the statistical tests used to identify real displacements a technique of exact...

The solution of the SOD problem furnishes the ideal distribution of the weights of the geodetic network observations. This paper attempts to make a contribution to the realization of such weights using EDM devices. From an analysis of the environmental and instrumental error sources, the contribution of each source to the total dispersion of the di...

The paper deals with an original method of designing optimal conditions of separability for geodetic network observations affected by outliers starting from the approach of standardized residuals from a principal component analysis.
In order to improve the separability of spurious observations by a certain oblique transformation of the principal co...

The paper presents a program performing the interactive and/or iterative improved design of a geodetic network. The program, written in ANSI FORTRAN 77 makes it possible to construct criterion matrices for the net point coordinates and for the vector of residuals of observations by the contraction of the eigenvalues and/or the rotation of the eigen...

The purpose of this work is to show how it is possible to transfer to analytical photogrammetry the FOD problem and the SOD problem. The used method consists in choosing a target value for a function of the variance-covariance matrix of the unknowns and in a repeated solution of the SOD problem, cancelling each time the observations with a non sign...

This paper deals with the improved design of an existing control network whenever a certain threshold of local and homogeneous strain field has to be detected. In order to construct a criterion matrix for the vectorized tensor of strain parameters and local rotation the technique applied to the sensitivity analysis is proposed. A new method of solv...

The paper deals with an original method for constructing a criterion matrix for deforming networks. This consists in the contraction of the eigenvalue spectrum and the rotation of the eigenvectors of a covariance matrix relating to a displacement point coordinate vector. For the rotation of the eigenvectors, the so-called “procrustean transformatio...

The vector of weights, which is the output of a second order design of an EDM geodetic net, has to be interpreted from the point of view of EDM field measurements. This paper evaluates the resolution of the chord length measurement and gives the consequent condition which the weights have to satisfy. An application to a net is given.-from Authors

This paper investigates the possibility offered by procrustean transformation for the construction of a criterion matrix for control networks when the condition of orthogonality between the “essential eigenvector components” and the direction of the forecast deformation is required.
Essential eigenvector components are here intended as the elements...

This paper proposes an original method of constructing a criterion matrix for the optimal design of control networks by means
of the contraction of the eigenvalues and the rotation of the eigenvectors of a covariance matrix. The rotation of the eigenvectors
is carried out by two different methods, that is through independent rotations of the pairs...

Riassunto L'articolo presenta un metodo originale di filtraggio dei dati laser altimetrici per la produzione dei Modelli Digitali del Terreno (DTM). L'individuazione dei punti non appartenenti al terreno (outliers) è condotta attraverso l'applicazione dell'algoritmo di ricerca dinamica BFS (Block Forward Search), proposto recentemente da Cerioli e...