The process of extracting geographic, statistical, geometric, or scientific information from one or more related collections of GIS features and data.

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4
votes
1answer
151 views

Finding tight corners on roads using ArcGIS Desktop?

Problem: How can I pinpoint tight corners on a road dataset that might cause longer/larger vehicles difficulty in driving around. Assumptions: Ignore turns into junctions. Just interested in ...
8
votes
4answers
322 views

Advice on choosing ideal software for consultancy

I am taking the step to start a small business consultancy using digital map technology to assist retail business to better understand their environment and make informed location based decision. My ...
3
votes
2answers
742 views

Can python read the value of a cell in a spreadsheet? [closed]

Can python read the value of a cell in a spreadsheet? The simplest example would be a script that ran a buffer tool on a given shapefile. For the distance parameter, instead of just using a number ...
5
votes
2answers
682 views

Spatial Analysis with Factors/Classifications

When doing analysis on spatial data with associated information that is numeric, it is possible to use techniques such as Kriging or Interpolation or Cluster Analysis to find out interesting ...
3
votes
2answers
204 views

Using the ArcGIS Local Routing Tool . . geoprocessing in the runtime

When I create a model in ArcGIS using the Network Analyst Tools, I am able to create Locations and make the Route Layer and Solve. However, I need to be able to add barriers as well as locations, ...
4
votes
3answers
2k views

Summing attributes intersected by under a radius

Apologies - new user. I am working with QGIS on Mac OS X and with shapefiles downloaded from the US Census Bureau that show population data by state and by county. How do I: select certain points ...
2
votes
1answer
312 views

Raster Analysis - Identifying features from Raster

I have an IDW, tension spline and hill-shade rasters that show an archaeological landscape and from these rasters I want to identify new features which are seen in the landscape as depressions. And ...
4
votes
2answers
241 views

Which GIS best for this problem?

This problem is similar to retail presence optimization. I'd like to know which GIS's could help us do the following: Given a set of point locations, create a circle of radius n meters around each. ...
3
votes
2answers
6k views

How do you use GIS to detect percentage of Land Use Change

I am a student in GIS I have a dissertation about land use change. I have questions about using ArcMap 10 for this aim, how can using GIS to detect the percentage of land use change. For example we ...
1
vote
1answer
214 views

Analyse spatial data and extract results in tabular form in QGIS

I'm sorry if this question is badly framed, I only started with GIS and QGIS 2 days ago so I don't know any terminology yet - I'll try to explain as best I can. I have 2 layers in QGIS (1.8, on ...
3
votes
0answers
758 views

Performing a Multicriteria Analysis Using Distance Along a Road Network

There is the possibility that I will be working on a project which will look at thousands of properties in a region and measure their accessibility to different services (schools, parks, hospitals, ...
3
votes
0answers
191 views

How to estimate the average width of a sidewalk? [duplicate]

I have a table with two polygons representing urban block with and without the sidewalk: geomBlock and geomBlockWithSidewalk. On my city we can approximate the polygons of geomBlockWithSidewalk to a ...
1
vote
4answers
602 views

Determining gradient of road segment

I've a shapefile of roads data. It contains information about terrain of road segments, i.e., hilly, flat, undulating, etc. I want to determine gradient of every road segment. I know this might ...
6
votes
6answers
2k views

How to calculate the maximum distance within a polygon in x-direction (east-west direction) in PostGIS?

I am interested in the maximum width of a polygon, e.g. a lake, in the east-west direction. Bounding boxes will help only in simple polygons but not in complex concave polygons.
1
vote
0answers
118 views

How to relate Slope map and Curvature map so as to have in the end PERCENTAGE PROBABILITY MAP?

i am trying to deal with road detection this last month. So i am working with particle filtering that produces particles, that means possible targets(to my case cars)/points, with hidden information ...
2
votes
1answer
203 views

How can I estimate kernel density, taking barriers (i.e. a priori zero-probability regions) into account?

How can I estimate kernel density, taking barriers (i.e. a priori zero-probability regions) into account? At the moment, regions where the population cannot occur are clipped out for display. ...
1
vote
1answer
1k views

How to compute mean coordinates?

Can anybody explain how to compute mean coordinates? Regards.
2
votes
0answers
426 views

How do I create a leader line for a label in my bar graph in ArcMap?

I am displaying a bar graph of various tornado watches and warnings along with the actual tornado touchdowns themselves. Since the tornado touchdowns are such a small number compared to the large ...
2
votes
0answers
528 views

Mean coordinates in QGIS

I am using QGIS v 1.7.4 for MAC and I am trying to calculate mean coordinates for a set of points using ftools. To calculate my result I am going to Vector -> Analysis tools -> mean ...
11
votes
1answer
612 views

QGis raster terrain analysis - The curvature filter puzzles me

I am a french Master student at university Grenoble INP, and during my master project I have worked on DEM (raster) terrain analysis. Thus, I have read the source code of several QGis-1.7.4 raster ...
8
votes
2answers
544 views

Finding polygons without right angles using Open Source GIS or ArcGIS for Desktop?

Now we are digitizing some buildings in specified area. The obligatory rule for this work - in most cases buildings should have right angles. We are using QGIS with CAD tools for this work but ...
1
vote
0answers
129 views

how to set in arcgis network analysis that use every road segment max m times? [closed]

excuse me if my english ins't good. I have one incident and 120 facility. i wanna set criteria in Arcgis network analysis that if any road segment used for example m times, for other route doesn't use ...
1
vote
1answer
306 views

ArcGis - batch frequency of point groups to single table?

I'm kind of new in the GIS world but have been finding my way around in forums and help places up to now. Still, there's one task I need to perform that I cannot get my head around it or even find ...
10
votes
5answers
2k views

Multicriteria Analysis : how to?

I have to do a multi-criteria analysis to answer the question : "which is the best lot to develop". A few of the criterias are : distance of the nearest bus stop (point layer with bus stops) ...
2
votes
1answer
441 views

How to calculate the Zone of Impact using OpenWind

After downloading OpenWind, I am trying to calculate the ZVI for a single Turbine. There is no documention regarding this from the developers. At this point I just want to compare the output of the ...
10
votes
1answer
417 views

Looking for a trajectory similarity measure

For my final academic work I have developed a compression algorithm for GPS trajectories. I can estimate the quality of the spatio-temporal compression by computing the syncronized euclidean distance ...
3
votes
2answers
1k views

How can I reproduce Getis-Ord GI* hot-spot analysis tool in QGIS?

I'm trying to find a hot-spot analysis plug-in for QGIS that would perform similarly to the Getis-Ord (Gi*) hot-spot analysis tool used in Arc, but have not been successful. Does anyone have a ...
3
votes
1answer
337 views

How To Determine Frequency Of Overlapping Polygons (Bounding-Boxes)

My starting point is a series of bounding box polygons, representing the extents of all the data sets in my inventory. I am trying to produce an output grid showing the frequency of coverage over the ...
3
votes
3answers
5k views

Income data on a block level: how does a newbie do it?

I am a complete newbie at GIS data, and am trying to do the following: Figure out census blocks in Miami-Dade (and several other counties) that have average household incomes > $75,000 Get the ...
4
votes
1answer
442 views

Analysing Information By Vector Grid

I have two vector line datasets and wish to compare the line lengths. While I have already compared the sum of the lengths, I'd like to conduct further analysis down to 250m, possibly lower. I'm ...
2
votes
2answers
166 views

Spatial analysis? Two layers?

One is LandPlot and the other is Soils. When I open the LandPlot attribute table I see I have 500 specific plots of land. When I open the Soils attribute table I see I have 5 types of soils (let's ...
2
votes
1answer
485 views

How to move a Point perpendicular from nearest Line?

I want to move Point perpendicular from nearest line or polygon, and the question is how to do that? example, I have points (house number) near roadbed, and I don't want them to intersect roadbed ...
1
vote
1answer
249 views

Heat Map to find 10 restaurants, 10 retail, and 10 stores open after 6pm within 3 linear blocks

I would like to find where in the City there is a combination of 10 restaurants, 10 retail, and 10 stores open after 6pm within 3 linear blocks. What is the best way to do this? What data would I need ...
3
votes
1answer
206 views

Efficiently classify raster with irregular polygons

I have a project on my desk to classify an elevation model using different elevation breaks for each polygon in the area of interest. In pseudo code: FOR each polygon IN layer: CREATE_MASK FROM ...
2
votes
2answers
2k views

Where can I download a free dataset containing major ports across the world?

I am working on an analysis and would like to incorporate major maritime ports from across the world. Some initial searching turned up a dataset produced by General Dynamics, however it will be ...
7
votes
2answers
767 views

Looking for advice regarding solar potential applications

I have the task of looking into whether it is possible to build a solar potential application which would inform the user whether a roof is suitable for solar panels and a brief report about the ...
7
votes
1answer
230 views

Analysis of GPS error

I'm wondering if there have been any studies which attempt to analyze or characterize GPS error distribution over different situations/conditions (e.g. surrounded by tall buildings/mountains, ...
4
votes
1answer
680 views

Is there an open source tool for both road network analysis and geocoding?

Is there any one open source software package that can perform both road network analysis and geocoding?
8
votes
3answers
731 views

Identification of consecutive points within a specified buffer

I have a point file, hourly relocations of an animal, and I want to be able to place a buffer around each point and calculate the number of subsequent points which are within the buffer zone. I am ...
9
votes
1answer
430 views

Open source GIS tool for mapping health data

Im looking for an open source desktop gis tool that can be used for visualization and exploratory analysis. I want it to be interactive and perhaps display two or more maps at the same time to allow ...
4
votes
1answer
355 views

How to create a service area using both streets and buslines in the same network?

I want to create a network analysis more difficult. Therefore, I want to calculate a Service Area around hospitals next to busstops. But: The network does not only consist of roads and ...
2
votes
1answer
527 views

How to integrate every single street into a network analysis?

This is my first question, but I solved problems before thanks to this great community! It is also my first time working with a network analysis (ArcMap 10) and there are some problems which haven't ...
11
votes
1answer
185 views

What spatial analysis did the US Supreme Court review in the Perry v. Perez opinion?

The Supreme Court recently issued an opinion on Perry v. Perez which seems like it must have involved evidence based on spatial analysis. The L.A. Times reports: The 9-0 decision set aside a new ...
3
votes
1answer
957 views

ArcGIS tool for indicating changes in land use

I have a couple of shapefiles in which there is some information about land use (polygons) such as water, forests, soils, buildings etc. Each of the shapefiles represents a certain year of the same ...
8
votes
2answers
999 views

TRI, TPI, or Roughness

I am working on a site selection projection where I will be unable to perform any in situ observations. A key component of the selection process is the ruggedness of the underlying terrain. I plan ...
4
votes
2answers
2k views

How to find the area of raster values within polygon zones?

I'm using ArcGIS 9.3 and I just can't seem to get this right - I've tried tabulate areas, zonal stats, converting to polygons, etc. I'm missing something somewhere. I have a USGS impervious surface ...
4
votes
2answers
336 views

Vector Analysis: Determining area of county land mass without water features

Here are the layers that I have: State / Province polygon file (With Area Field) County / Ward polygon (with no area field), but all the polygons are within the state boundaries Water ways for the ...
5
votes
1answer
391 views

How to find upstream - lateral and downstream zones around urban areas?

I've a DTM and a shapefile of built-up areas. For a fire risk model, I've to find (within a defined buffer zone) two zones around built-up areas: one that is above/higher and lateral and the other ...
6
votes
1answer
1k views

Nearest Neighbor calculation in PostGIS

I'm learning how to use PostGIS and spatial databases for analysis. What I am trying to do is perform a calculation to get the distance for the nearest polygon in a file, using the edge calculation, ...
5
votes
5answers
2k views

Spatial Join on two point featureclasses produces empty output featureclass

I have two point featureclasses that intersect each other. They are in the same projection and dataframe. The issue is, when I perform a Spatial Join the output point featureclass is empty. The file ...