Questions related to Geospatial Science
The sensible choice of gamma, which generates the output values between the “increasive” trends of fuzzy algebraic sums and the “decreasive” effects of fuzzy algebraic products.
But, how can I come to know, which gamma value is suitable for my output?
I have noticed some really visually aesthetic and informative flowchart of methodologies in different remote sensing articles (example of such high quality flow chart is given below). I would like to know how to create such a flow chart or which software can be used for this purpose?
We think to test this hypothesis in Morocco within our research project, but we wonder if the error in the absolute altitude could prevent from using these data to this goal.
I would like to suggest you take the survey "NSDI FOR YOU AND YOUR COUNTRY":
The results of this survey will help me to research the issues of the implementation of NSDI and get an overview of this policy.
I will be very grateful for your help, cooperation and sharing!
Actually ,I want to use landuse data in swat model, I download the landuse data from USGS and want to process in Erdas imagine for using swat model. How can one process this data and which steps are necessary for this process? Thanks for your positive response
I've recently come across taxi trajectory analysis as an interesting topic in GIS/transportation. I thought it would be great if everybody here can share his/her experience in this field and introduce any researchers, good papers or corporations leading in this area.
Aerial Laser Scanning Data is being more and more widely used across all Europe. Recently Great Britain decided to provide free access to aerial scanning data (starting on September 1st. 2016).
I know that Netherlands also provide free access to their laser scanning data (AHN 2 database of more than 600 billion x,y,z measured points)
I have also learned that Slovenia has released their LIDAR data as well, and also heard that North-Rhine Westfalia decided recently to open access to LIDAR data of their territory.
Are there any other EU States, which also decided to open free of charge access for their LIDAR datasets ?
Recently been asked to describe some challenges when designing or implementing a geodatabase and how the challenges were addressed.
I have seen some papers and scientific scripts mentioning both and claiming application of IoT in GIS but I couldn't find suitable and enough papers. If you know any good paper or have any idea please share with me.
thanks in advance.
As is well known, the Discrete Fourier Transform (DFT) is one of the main tools for digital signal analysis in electrical engineering and related fields. Now the question is:
Do you think the the Discrete Fourier Transform is deeply understood in the Geospatial community?
Although DFT was used in several areas of geospatial sciences such the Filtering of Digital Terrain Models, digial image processig, pattern recognition, its theoretical principles and their implications may not be deeply understood in the geospatial community.
What is space? Is it what is conceived by Newton or by Leibniz? Both Newtonian and Leibnizian views of space are framed under the mechanistic thinking of Descartes back to the 17th century. Christopher Alexander in his life's work - The Nature of Order conceived and developed a brilliant new view of space: space is neither lifeless nor neutral, but a living structure capable of being more living or less living. This new view of space has some far-reaching implications. It implies that we make space or our built environment better, smarter, or more sustainable, or more livable, or more resilient. More importantly, it implies that goodness of space is a matter of fact rather than an opinion. In this paper, we attempted to provide empirical evidence space indeed has different degree of beauty or life:
By asking this question, what I really wanted to know how long it will take for us to adopt Alexandrine view of space. Benoit Mandelbrot said Euclidean shapes are cold and dry, but nature, traditional buildings and artifacts are full of living structures, as noted by Christopher Alexander.
Am Trying to model local TEC component at an East Africa Location using GNSS receivers. Anybody with similar experience local TEC especially at an equatorial location. Collaboration is also welcome
Dept. Of Geospatial & Space Technology - UON
C. M. Lwanga
In the last couple of months, we have seen an explosion in the blockchain technology mass media coverage, which surged the value of the great majority of crypto currencies worldwide.
I am not interested in the speculation side of this market, but more in the distributed de-centralised system that blockchain provides.
Applications of blockchain is wide, but still, only a few of geospatial examples are found on the internet.
Are you aware of, or can you imagine, a good geospatial application that runs on blockchain?
ps: avoid the public parcels ledger (register) example, that is the most obvious, I am looking for originality.
I am looking for both basic information about this statistical method and appropriate software to run some analysis. Thanks!
Hello everyone, I'm doing work about solute transportation in soil. There are 40 sample points and in GS+ software, active lag distance is default as half of sample distance. After calculation, only four or five plotted points were showed, but R2 is more than 0.9. Is this analysis reliable? How many plotted points are needed at least?
I have used AHP, Frequency Ratio (FR), and Fuzzy Logic (FL) to create land suitability maps in the GIS environment. Do you know other methods?
I am currently embarking on a research on climate change modeling using geospatial technique, CO2 raster data could be very useful in this research.
I've tried with the following software:
1. Sentinel-1 toolbox - I can open the GRD IW data but can't apply the Polarimetry tools. When I use the tools with SLC IW I get errors.
2. PolsarPro - Only SLC IW data can be imported. The Polarimetry tools work fine with this product.
3. Envi Sarscape - Only SLC IW data can be imported with success, when I try to import GRD IW data I get a error.
Space debris include space junk, space waste and defunct objects in orbit around Earth. It includes spent rocket, old satellites and fragments and they pollute space. They usually can be tracked, but how about measuring their quantity and relating the values to threshold limits?
I am looking for a Python library or API that facilitates the creation of geo-spatial topologies and is able save them to a portable format, such as TopoJSON or GML.
The main goal is to save space in detailed polygonal topologies, with borders defined only once and shared among adjacent polygons.
I am trying to create a tree based on the geographic range centroids for 93 taxa. I have used cluster analysis in Mesquite to create a couple of trees but I am very new to this and am not sure whether Mesquite is the best program for this, or, while in Mesquite, whether I should be using UPGMA or single-linkage. Any help that can be provided would be greatly appreciated!
I have downloaded level 1Gst and level 1T hyperion hyperspectral data for my study area, in order to use in mineral mapping, however, every time I try use FLAASH for atmospheric correction it gives an errors or bad results. Should I use the toolkit then subset (removeing bad bands) then FLAASH or not? Also should I put specific advanced paramters in FLAASH?
How I use FLAASH atmospheric correction using ENVI (what ideal parameters for such data sets)?
i am trying to convert a polygon map to raster map so as to reclassify the map but it is not working out well.The original map has four sets of polygon but on converting to raster only two polygons are reflected.
I am trying to find out an approach to effectively and accurately identify and extract various horizontal curves (e.g., simple curve, compound curve, reverse curve and spiral curve) and obtain curve location, radius, and curve length in an automated and time-efficient way.
However, I tried some ways on this study, there are several problems I can't solve right now:
a. Inconsistency of roadway alignment in the ArcGIS map.
Problem: the inconsistency of roadway alignment in the GIS map results Type I error. Some road segments are curving or smooth in actual roadway but mapped as straight line in GIS map. It will result the obtained curve radius changing dramatically in the same segment.
b. Segments breakpoints in Database
Problem: the improper sequence of segment in database is a major cause that contributes of Type II error.
c. ArcGIS map alignment accuracy
The better accuracy of roadway polyline shape file can get better results. However, currently, the available ArcGIS map is not high accurate. That’s the possible reason why the most common methods to identify and extract horizontal curve data are based on Global Positioning System (GPS) data.
Any ideas or suggestion? thanks.
In modern LST is a key component. So for estimation of LST it is important to measure it from Geospatial technology
Is it possible to create a 3D geological model using ArcScene in order to help reserve calculation/estimates ?
Nangone is "a coral island" referred to as being in Melanesia in the Pacific, somehow connected to Easter Island. Does anyone know how to find it?
I have to use to OTSU algo on T-cap Greenness component in order to find out the threshold above/below which i can figure it out as vegetation/agriculture/urban greenery.
As i have used MATLAB...(with "graythresh" function) and tried ENVI Image Change Workflow... (where i get a change detection difference map with threshold technique of OTSU).
What is the expected out for this...?
I have downloaded Landsat 7 surface reflectance products, How to use that in the calculation of EVI? and What should be the range of values in output
Strip Map Mode: 80 km swath, 5 x 5 m spatial resolution
Interferometric Wide Swath: 250 km swath, 5 x 20 m spatial resolution
Field inventory is in 120 plot (600m2)
I just get to know about GeoPDF. Can this technique be used by private researchers? If I want to create or edit a GeoPDF file without any commercial software, is it possible (by coding I mean) ? Is GeoPDF open source? Thank you for any one giving me guidance.
I am setting up a map template to automate map production at global scale using ArcGIS 10.3, and some problems arise when displaying countries at the verges (longitude) of global map (i.e. Pacific islands such as Fiji). I successfully manage to run the data driven pages tool to produce bulks of maps but when getting those countries at the verge of global map it zooms out to a global map view (because some parts of the country may fall in the "left side/limit" and other in the "right side/limit"). It's a little bit tricky and I thought that maybe using a spherical based coordinate system I will manage to sort it out, won't I? Does anyone come up with other suggestion?
Thanks in advance.
What is the explanation behind the difference in NDVI values when calculated from DN, radiance and reflectance?
I'm interested in using projection pursuit for decorrelating variables in geostatistical simulation, but a don't want to start from zero if there is any previous code.
To my surprise many countries appear to report to the FAO every 5-years on forest extent statistics without using satellite Remote Sensing. I would appreciate to learn about countries that do use RS in their FRA. And for those countries that do not, about their motivation.
For an example of uncertainties in FRA forest extent statistics, please refer to my profile.
When we analysis some change pattern or spatial density distribution, we could create a grid with m columns and n rows to do analysis. As we know that the MAUP is an important problem is spatial analysis. If the grid number and grid size were set not correctly, the results may be wrong.
For example someone cerat a gridnet with 100 columns and 100 rows , and the grid size is 5km*5Km to analysis some point data density distribution. However, few of them tell us why the grid size is 5km? Why just create a gridnet with 100 columns *100 rows to do analysis?
So how to set the grid number and grid size according to our experimetal data? In other words, is there any method to determine the grid number and gride size?
I am planning for a land surface temperature map of 1990. and want to see change in land surface temperature of my study area. Both 2000 and 2010 temperature are coming good but 1990 Landsat thermal band showing abnormally low temperature compared with 2000 and 2010 temperature calculated for Land surface temperature.
Does any one know how to query available Landsat and MODIS data within one map?
Sometimes, I do not know the path/row (h/v) corresponding Landsat and MODIS at the study area. I need to find these information at separated website, and it may not corrected when study area is located at the corner of Landsat or MODIS.
So, if there were one website can provide the location map of Landsat and MODIS simultaneously, it will save time.
I am using the StereoSAR modual of ERDAS IMAGINE to construct a DEM. And it seems the result of "match" step determines the quality of the final DEM. However, my self-defined correlator always performd worse than the pre-defined correlator. I want to ask is there any principle about how to set the parameter of a match correlator?
One of my main research interest is to find analytical and numerical solutions to the non-linearity of the photogrammetric orientation algorithms, which I do believe is one of the main reasons that slows the acceptance of photogrammetry as a generic 3D measurement technology. Now the question is: Does the non-linearity of the photogrammetric orientation algorithms is solved? Or there are some remaining issues?
It seems to me that ESRI ArcGIS has been dominant in GIS and spatial visualization and analysis applications for some time. However, some of my students have been talking about other GIS software. I know that QGIS is pretty popular as far as free and alternative GIS software goes. Has anyone out there used it for research or engineering that can share their experience? What do you like and dislike about it? How easy is it to learn? Is there a reason to use this free software as opposed to proprietary GIS software?
Secondly please guide me, is it possible in Arc GIS 10.2 that all points will go to respective coordinates in images. so I do not need to individually write coordinate one by one and train it?
We developed several machine learning techniques for growth stages classification based on MODIS (or later incorporating LANDSAT). Currently, we obtained results on our own annotated dataset based on field survey. Are there some open annotated dataset that we can compare our algorithms to this data?
I know the principle of Modtran doing atmospheric correction,but i doubt is it the same using the Modtran and the FLAASH(a module in ENVI ),even though I know the FLAASH is based on Modtran. Could anyone tell me the connection and difference between using Modtran and using FLAASH when ding atmospheric correation?And can the FLAASH be used doing atmospheric correction for quantitative RS, especially for SST retrieval in case2 waters.
Landsat provides beautiful data of ocean SST at 100 m resolution ... still there is an annoying stripe pattern in the images in the channel 10 (thermal infrared). Does any one has a correction for that? Here is an example from September 10, 2014 over the west coast of France.
If anyone can direct me to publication(s) that talk about how or why soil disturbance would lead to faster establishment of forbs over grasses. Thank you!
Dear all, I have field data of vegetation cover and soil's mechanical Composition and Analysis of soil chemical data. So far I computed a desertification map by remote sensing data. How can I accuracy make an assessment between desertification map and field data? How can I check my result? Please help me.
Which kind of program best in this process erdas or envi? Please send me some lesson. Actually I don't know how do this process. Thank you
We are in search of a methodology that is suitable for determining an index of soil quality from the establishment of a geographic information system
I want to use the linear spectral mixture model through end member selection. But now many researchers all use envi remoted sensing software. I found the puried pixels selection tools in envi is inconvenient. For example, there are so many roofs with different colors. The puried pixels usually select one of the roofs as the end member. It dont represent the all roof imperviousness. Is there the other soft tools to select end member ,eg, erdas. How does it operate?
I have problem in smoothing the slope derived from digital elevation model. I want to do filter for the slope <5 degree in 7 X 7 kernel size, 5-20 degree in 5X5 kernel and >20 degree slope in 3X3. But I am not able to put these kernel size condition in filter tools in ArcGIS Desktop 9.3.
I'm currently trying to find the change in value between two dates for a couple vegetation indices generated from two different types of Landsat data. The first image is a TM image from 2011 and the second is a 2013 Landsat 8 OLI image. Both images are georegistered and converted to atmospherically corrected TOA values. While doing some preliminary investigating, I found that the values for unchanged landscape features are significantly different between dates. I'm wondering if this is a result of the difference in radiometric resolution between the sensors (8bit vs 12bit). The Landsat 8 values appear to be lower in a number of areas compared to the TM. Whats should I do to accurately difference the images?
I have 3 raster layers in GIS, i want to identify the maximum point in each raster, which is simple using cell statistic in ArcGIS. However, i also want to know which raster each maximum value came from. Any Ideas?
Is digitizing of map features completely dead?
For example, when and why do you still digitize features from a map?
It can be heads digitizing up from a scanned paper map (or image, or whatever) or using a traditional digitizing tablet. It can also just be digital and heads-up (i.e. you never had the paper map).
Do you ever still utilize manual feature digitization to create points, lines, or polygons?
I need this information for a statistical technique I am developing.
Any VGIS examples?
Recently, USGS provide provisional Landsat 8 surface reflectance product (L8SR), which combined with data from Landsat 7 surface reflectance product (LEDAPS), give a unique opportunity to analyze every eight days the changes of vegetation cycle all over the word.
The problem is that the Landsat 7 images are affected by the problem of the failure of the Scan Line Corrector so many data are not available.
There are Open Source software can gapfill the missing data?
Obviously MOIDS VI products are corrected (to some extents) for cloud shadows. But how about topographic shadows? If yes, any information on DEM and methodology used for corrections?
If no, to what extent do you think VIs (particularly NDVI) in C5 are affected by topography and illumination/viewing geometry? As far as the general appearance of the vegetation cover is concerned, my focus is not on "trees", but mostly on grass, shrubs, and subshrubs. Can I also have some suggestions from your own experiences with correcting topographic, viewing/illumination effects on NDVI?
Hi all, I have some data I need to interpolate.
Data are a set of scalar values (measurements); for each value, I have a two-dimensional probability map (ranging from 0 to 1) depicted in the image attached. The map is almost everywhere zero (or random noise) and shows some peaks where the probability of the measure is higher.
Each scalar value has its own two-dimensional probability map.
I want to interpolate these measurements in all the space of the probability map.
My first attempt has been using a function of the distance. For each point P0 where I want to interpolate data, I evaluate the distance between P0 and the points of the map, and I use a ratio between the probability of a measurement and the distance from P0. For each measurement, I evaluate the maximum of this ratio and I eventually evaluate a simple weighted average of the measurements. This method works, but it is really sensitive to the way I evaluate the ratio and the function of the distance.
How can I do this interpolation?
Regardless of the form or method used, should we take consider all biotic and abiotic factors of the physical environment or only the climat indicator (IC) and topography indicator (ITP) ?
Thank you for answering my question.
When we use the moving window to calculate density distribution in spatial analysis, the window size is a key parameter. While few of the researches talked about how to determine the window size.
For example, someone only told us he used a 3*3 window to do analysis. But why is 3*3? Maybe if we change the window size, the result may be different.
Will you please give me some advices about to determining the window size? Is there any criterion?
I am using a combined dataset of Landsat TM, ETM+ and Chinese HJ-1 A/B CCD sensors images coincident with the in situ measured Suspended Solid Concentrations (SSC) for my study area Hong Kong. All these sensors are similar in spatial resolution (30 m), bands designations and data bit levels (8 bit). I have used the four bands Blue, Green, Red and NIR to find their correlation with coincident SSC.
I am observing a low correlation between NIR and SSC, while in literature a higher correlation has been reported.
Can someone explain why there is low correlation between NIR band and SSC for my study area?
Can this be attributed to the specific grain size and particle size distribution of the suspended solids found in this region?
Any comments will be appreciated.
Most of the previous researches focus on city level (i.e. Beijing or Guangzhou ), using remote sing images to obtain land information and landscape metrics to analyse the changing patterns. Some of previous researches focus on discovering the changing progress in different regions and then compare them. Some of them focus on methodology innovation such as information extraction or putting forward new landscape metrics.
However research at Megalopolis level is less than at city level. What are the differences in scientific problem, method and theory between researches at city level and researches at Megalopolis level? Doing research at Megalopolis level , what (or which aspect) should we pay more attention to than at city level?
Could anyone give me some tips?
As I am digitizing polygons in 10.2 ArcGIS, sometimes the vertices are getting deleted automatically and also it does not close as it should by clicking on the last vertex.
2. The final product has an altered shape that it takes on its own.
3. Even while editing vertices as I add a new vertex it deletes the previous one.
4. Also, I tried converting from lines to polygon. That also does not match exactly.
I am frustrated. Any help would be appreciated.
I am trying to classify images of different dates in ENVI using a supervised classification.
I have defined ROIs for one year (2009) and classified that image. However, when classifying other images (from 1970 - 2013) do I have to define new ROIs for each image or can I use the ones from the 2009 image,
Essentially does ENVI store the spectral reflectance info from my original 2009 ROIs on other images when doing supervised classification or does it simply recalculate spectral reflectance for each class for each year - meaning that I must have new ROIs for each year?
I have three different satellite Images from three different time periods, one from Landsat 8 (30 m), another from ASTER (15m) and one from MODIS (250 m). The objective here is to do a multi-temporal land cover change detection analysis study with the help of Digital Image Classification. I plan to first do the Image Classification for the three images separately and then resample the coarser spatial resolution images to the geometry of the finer spatial resolution, i.e., MODIS (250 m) to 15m pixel size and Landsat (30m) to 15m pixel size respectively for the sake of comparison. Finally after resampling with a Nearest Neighbor Interpolation method I would go ahead with the change detection process.
I am curious to learn whether this is the right approach or are there better means of achieving the desired result?