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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3
votes
2answers
203 views

Hillshade for 30m NED at continental scale

I'm new to terrain analysis. I have a 30m NED DEM (.tif) for the conterminous US. I would like to generate a nice looking hillshade for the US, but it looks bad - as in pixelated and rough (See ...
1
vote
2answers
662 views

Find and list all polygons that overlap with another polygon

I am working with two polygon layers which overlap but are unrelated (one is congressional district boundaries, the other is MPO area boundaries). I would like to generate a list of all the ...
4
votes
4answers
312 views

How to computational efficiently check if there are any overlapping polygons in a group of polygons?

I need to do some processing with groups of polygons. If any of the polygons in the group overlaps other polygon the result is unpredictable and don't throw any error. So, I need to detect if there is ...
2
votes
1answer
980 views

Watershed Analysis using DEM [duplicate]

I stumbled upon your question regarding the mosaic feature in qgis, the thing is I'm also using Quantum and this is my first encounter with GIS this semester, so if you can please help me with a ...
0
votes
0answers
54 views

How to add attribute from analysis to database mySQL?

I need to prepare a GIS for a customer. They insist to use a MySQL-Database (not the best option, I know). They need to digitize some geometries (areas) and add some attributes. The geometries and ...
1
vote
1answer
83 views

Basic traffic volume map [duplicate]

I'm trying to map the volume of people traveling from various cities to popular mountain towns in British Columbia. I have a .csv containing the starting point, ending point and number of travelers. ...
2
votes
6answers
207 views

GIS used to analyse micro-environment

Can anybody give me some articles or show me some link where GIS is used to analyse and manage micro-environment, such as a college campus or a small locality. I need to do a project on ...
1
vote
0answers
56 views

3D tool for a visual analysis

Given a 3D mesh I need to visualize and analyze properties and elements generated from the object such as: tensors coplanar/similar elements ( coplanar faces, aligned vertices, etc etc, 3D geometry ...
0
votes
0answers
560 views

Sextane script error (os is not defined)

I want to build an analysis script using Sextante 1.0.9 on QGIS 1.8.0. I find an example script in Youtube. I tried this code but never worked always getting error. People say that Sextante is ...
2
votes
1answer
59 views

Clipping a buffer from network analyst shapefile to a base shapefile

I have exported my polygon shapefile which I got after I ran my Network Analyst into a shapefile. It has 6 buffer zones (delimited by time in increments of 10 minutes). When I check the attribute ...
2
votes
1answer
584 views

ArcMap 10.1 Spatial Join: 'Contains' and 'Within' question

I have two polygon datasets: electoral districts and postal code areas. I'm performing a spatial join to see which postal code areas are completely within a district (the area can touch the borders, ...
0
votes
1answer
236 views

Calculating sinuosity of a path with GME in ArcGIS 10?

Does anyone have any experience with pathmetrics in GME? I would ideally like to use the old Hawths's tool "line metrics" for calculating sinuosity of a daily path but I have ArcGIS 10. I downloaded ...
15
votes
1answer
615 views

Heatmap algorithm to visualise point diversity

Can anyone suggest an algorithm to generate a heatmap for visualising point diversity? An example application would be for mapping areas of high species diversity. For some species, every single plant ...
7
votes
2answers
2k views

How to create noise maps? (open source or scripted in ArcGIS)

In a previous role I helped create Noise Maps for Northern England. The predicted noise levels was done using the IMMI package (which I can recommend) and the cartographic output was done in ArcMap. ...
1
vote
1answer
94 views

Is it possible to Clip in ArcExplorer?

Is it possible to clip in Desktop Explorer? Or does anyone know of any Analysis Servers I can connect to to get it?
7
votes
3answers
3k views

How to analyze differences between two shape files and put results into a new shape?

I have two polygon shape files of the same region from two different years (1985 and 1997) and I need to analyse the differences between the two shapes resulting in a third polygon shape file ...
3
votes
1answer
97 views

Find out tight corners on roads

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
268 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
477 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
341 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
141 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, ...
3
votes
3answers
728 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
197 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
219 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
3k 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
178 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
553 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
2answers
562 views

Creating dynamic GIS charts in ArcGIS 10.1

I have generated a table which has road segments which get inundated during different flood events. I want to be able to add a pie chart to the map which shows that during each flood ARI (1y, 2y, 5y, ...
3
votes
0answers
181 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
3answers
307 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
1k 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
99 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
154 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
420 views

How to compute mean coordinates?

Can anybody explain how to compute mean coordinates? Regards.
2
votes
0answers
230 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
1answer
735 views

Modelbuilder - Feature Dataset Iterator

I had posted this on the ArcGIS forums, but thought I may get some further input here. Having issues acquiring the appropriate input and erase features during the iteration process. Please see ...
1
vote
0answers
261 views

mean coordinates in qGIS

I am using qGIS v 1.7.4 for MAC and trying to calculate mean coordinates for a set of points using ftools. To calculate my result I am going to Vector -> Analysis tools -> mean coordinates and ...
11
votes
1answer
448 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
360 views

Finding polygons without right angles

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
110 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
224 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 ...
2
votes
1answer
732 views

Hotspot Analysis: Low Values showing as hotspots

Im running hotspot analysis on point data, attempting to examine pollution emissions. I ran spatial autocorrelation first in order to determine the default distance threshold to use in the fixed ...
9
votes
5answers
886 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
280 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 ...
9
votes
1answer
224 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
484 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
262 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 ...
2
votes
3answers
3k 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
399 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
160 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 ...