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
719 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
810 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
445 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
372 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
550 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
190 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
1k 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 ...
9
votes
2answers
1k 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 ...
5
votes
1answer
397 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 ...
19
votes
2answers
331 views

Ways of expressing geographic questions in machine readable form

A core concept of GIS is answering questions about datasets. From the point of view of a database; SQL with spatial extensions is a way of asking such questions. What other ways can questions be ...
7
votes
3answers
323 views

How to check if parcel is located by golf course

Is there any simple way for me to run millions of parcels through some type of script to see if a shape file parcel is on a golf course? For example if I have a layer that has all the golf courses and ...
8
votes
4answers
1k views

What is spatial query tool for laymen?

I know nothing about GIS, but I have what I think is a GIS problem. From spending a few hours googling my problem, I think what I need to do is perform a spatial query, but I'm not sure how to go ...
11
votes
2answers
191 views

How could I rate roads for scenic drives?

relative GIS newbie here. I've been working on a personal project to rate roads on how nice a ride they'd be on a motorcycle. I wrote a Python program to work through road data in the TIGER dataset ...
8
votes
3answers
1k views

Temporal Analysis Tool: Seeking

I am looking for an alternative tool (proprietary or FOSS) that matches the functionality of Temporal Analyst for ArcGIS by DHI Software. The best I could get was the QGIS plugin Time Manager ...
4
votes
2answers
1k views

How can I calculate the vertical distance to the nearest water?

Summary: I would like to create a raster where each cell contains the vertical distance to the nearest water (a decent approximation would be acceptable). The problem is that I'm not sure how to go ...
7
votes
4answers
3k views

GIS Project Workflow?

If you had to teach someone the key stages to a typical GIS Analysis project, what would be the best generic answer? I would like to see diagrams to illustrate this point. Do not think it requires ...
4
votes
2answers
869 views

Plugin for average distance from node to polyline in QGIS?

Is there a plugin available that will calculate this? EDIT 1: The red polyline is the average distance of the point to the black polyline. The red polyline is what I want to display. Alternatively, ...
11
votes
1answer
464 views

Spatial operators in R?

How can I do spatial selections or filters in R? I can do this in PostGIS using (e.g.): SELECT * FROM mypoint, mypoly WHERE ST_Within(mypoint.geom, mypoly.geom); and it is similarly a piece of cake ...
10
votes
2answers
998 views

Is there a described GIS method for creating catchment areas based on nearest driving distance?

ie. a combination of Voronoi polygons with isochrones, so that the Voronoi polygons are based on driving distance instead of Euclidean distance. Is there a name or a described method for this?
6
votes
2answers
189 views

What multiplier would you use for calculating estimated population?

Given a number of address points in a given area, what multiplier would you use for calculating estimated population? I have seen 2.5 in a few places, but I was wondering what the generally accepted ...
28
votes
8answers
3k views

When is a 3D Visualisation in GIS Useful?

I can currently only think of two cases: to visualise potential changes in a landscape, such as the effect of adding windfarms, or the addition of a new building to an urban area. However both these ...
12
votes
3answers
331 views

What practices are available for modelling land suitability?

I currently use a "classic" raster based approach of dividing a study area into cells. All input layers are converted to rasters at the same cell resolution and given a suitability rating. A final ...
3
votes
3answers
981 views

Using National Agriculture Statistics Service (NASS) county level crop data to estimate crop acreage in hydrologic regions?

National Agriculture Statistics Service (NASS) provides county level crop (Corn, Soybean, Sorghum, etc) data. I want to calculate crop acres on each subwatershed from the county based data. I'm ...
7
votes
4answers
4k views

How to calculate polygon length and width using open source GIS?

How can I calculate the length and with of polygons using open source tools? By "polygon length" I mean the length of the longest line within the polygon (update: to be correct, I just need the ...
7
votes
3answers
2k views

How to interpret GRASS v.kernel results?

GRASS manual reads: v.kernel - Generates a raster density map from vector points data using a moving 2D isotropic Gaussian kernel ... Ok, but how do I interpret the results? I understand that ...
11
votes
2answers
3k views

How to calculate average slope in a grid?

This is actually a two part question: Which methods are there to calculate average slope by unit (say km²) for a given area? Are there any special requirements on the data - like additional ...
7
votes
3answers
665 views

How to get a list of adjacent lots to a road in ArcMAP and PostGIS/QGIS?

In the following map, I have: A line / road layer A parcel / lot layer The Task: Find and count the list of lots adjacent to the road with their types (parcel_type is a field in the parcel ...
8
votes
3answers
2k views

How to emulate Google Maps driving directions using pgRouting?

Would like to emulate google maps' driving directions functionality but use pgRouting instead. google's data over the project area & scale is quite a bit off so we want to use our own transport ...
8
votes
4answers
2k views

How to represent bimodal attribute value distributions on a map

I'm looking for a visualisation method that enables me to represent bimodal or even multimodal attribute value distributions on line features. A bimodal distribution has two different modes that ...
6
votes
3answers
1k views

Calculating Length of Linestrings in WGS84 in Miles

I have a few thousand LINESTRING features in a MySQL database. I'm trying to figure out the cumulative length of all the lines -- in miles. Using the GLength function I can retrieve the length in ...
5
votes
2answers
611 views

Disaggregating aggregate GIS data using remote sensing

I haven't really done much with remote sensing imagery. I have census data for an area, and a TIFF raster image of the area. I'm sure this is possible, is there a simple way to disaggregate the ...
10
votes
4answers
810 views

Point Pattern Analysis Algorithms

I'm looking for point pattern analysis algorithms and literature on point pattern analysis, online resources and book titles welcome. The topics may range from general descriptions of algorithms to ...