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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9 views

Raster Analysis Grid (Interpolation) Crashes

Upon clicking on "Grid (Interpolation)" QGIS crashes. I running QGIS 2.2.0-Valmiera on a Mac with OS X 10.9.4 Thank you for any trouble shooting guidance
3
votes
1answer
42 views

Statistical Analysis of Shapefile Proximity within Raster Image - ArcMap10.1

I have a raster image that has been reclassified into 15 equally incremented values/levels. This raster represents "sinkhole risk" in a certain county. So level 1 is the lowest risk region and level ...
4
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1answer
315 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 ...
0
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2answers
35 views

Frequency analysis and overlay analysis

Am new to gis and I hope to find help here. I am working on a research that requires that I overlay conditions of drainage systems and quality of healthcare in a coastal state to get areas which have ...
0
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1answer
77 views

How to colour contour lines in .shp file when the lines are not meeting in QGIS?

I am doing bathymetry analysis, where I would like to color the contours one by one in the case land is rising (or sea level going down). There is a comprehensive explanation about coloring contours ...
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2answers
2k views

Creating noise maps using ArcGIS for Desktop or Open Source Desktop GIS?

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. ...
2
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2answers
78 views

Identify cluster centroids

I have a data set of points which are grouped into clusters like so: I'd like to use ArcGIS or Python to create a point layer of the centroids of each cluster but I can't seem to find the right ...
16
votes
1answer
302 views

What GIS analysis techniques were used in determining Gale Crater as the landing site for the Curiosity Rover?

What specific GIS analysis was used in determining Gale Crater as the landing site for the Curiosity Rover? I'm assuming factors such as slope, elevation, ruggedness, etc were used as well as ...
2
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0answers
36 views

FME - Raster Algebra and Multicriteria Analysis

I'm trying to use FME to do some raster algebra for some Multi-Criteria Analysis. At the moment, I have three rasters, all with the same extents and resolution: Slope, Hydro, and Infrastructure Mask. ...
3
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3answers
646 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 ...
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 ...
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1answer
55 views

How to dissolve adjacent parcels by same owner but include those parcels located across the street with the same owner?

In trying to determine the total contiguous stream length per landowner, I dissolved parcels by parcel owner name attribute and intersected these dissolved parcels with streams. However, dissolving ...
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0answers
46 views

network based interpolation methods, which one could I use?

I need to interpolate traffic data consisting in raw number of vehicles passing across certain points, where counters are. It is evident I haven't a uniform distribution of points and values about ...
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0answers
55 views

Finding shortest cumulative route (i.e. best 'hub') between networked points

How do I find the shortest cumulative route (i.e. best 'hub') between networked points? I have a dataset where some but not all of the points in the network connect to each other, however it is ...
9
votes
1answer
191 views

When dealing with rasters of varying resolutions should one resample to the highest or lowest resolution?

I'm looking for recommendations on best practices for dealing with raster data layers with different resolutions and projections. The advice I've been given is to always resample to the layer with the ...
3
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2answers
37 views

What type of remote sensing methodology is commonly used to locate and track the movement of woodland caribou herds?

I am most curious whether it is possible to use Landsat or other freely available imagery (but info on any other method would great as well) to locate and track the movement of woodland caribou herds ...
2
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0answers
49 views

How to create cost surface for least cost water transport analysis?

I am working on a project to derive least cost pathways between sites by dug out canoe travel. Has anyone worked on a similar project or found a function like the Tobler hiking function that can be ...
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0answers
31 views

Analyse effect of groups on raster maps

I work with a mechanistic model that uses climate data to simulate some specific output for different time steps and spatial locations. Now I want to investigate the effect of different climate data ...
3
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0answers
67 views

Calculate field of view / angle of a point to a shapefile

I am trying to automate a calculation of the blocked fraction of a field of view from a point to a shapefile. I.e. find α in , such that α / 360 gives me the fraction of the field of view covered ...
12
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4answers
15k views

Extract coordinates of polygon vertices in ArcMap 10?

I've got about a dozen polygons in a feature class loaded in ArcMap 10, all in geographic WGS 1984. How do I easily obtain the coordinates associated with each vertex of each polygon in that feature ...
1
vote
1answer
54 views

Calculating distance between borders when one polygon inside another polygon?

I am brand new to ArcGIS and having some trouble. I would like to calculate the distances between the border of one polygon to another polygon. However, these polygons overlap. Thus when I use the ...
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 ...
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0answers
53 views

Efficient manner to buffer streams with multiple attributes?

I need to buffer a very large, complex hydro vector layer based on different water quality designations and surrounding slope. Different water quality classifications have different buffer ...
7
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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 ...
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0answers
28 views

Why don't my service area polygons follow my network?

I have found a few similar questions, but no good answers, so here goes another Service area question: I'm working on creating a walking distance layer from Parks, and have a road network set up with ...
0
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1answer
151 views

Creating flat end type polylineline buffer in model without ArcGIS advanced

I have a polyline split into many short segments and would like to create a flat end buffer for each individual segment (not "dissolve" them all into one feature). Is there any way to do this in an ...
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0answers
70 views

Calculate ANOVA using GIS

It's possible to calculate a statistic like ANOVA using GIS. I'm using ArcGis, but there's any GIS software to calculate it? Thanks,
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0answers
47 views

How to Create Polygon shapefile based on change in point value?

Is there a function in ArcGIS that would take analyze the adjacent point or polygon based on percent difference. If the adjacent value is within less than the percent it would dissolve otherwise ...
2
votes
1answer
96 views

Is there a limit to the amount of data in a spatial join in QGIS?

I am using Quantum GIS and trying to spatially join a point grid with polygons that are overlapping. If I get the sum of intersecting features, then I can get a good raster value. Well, every time I ...
1
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1answer
41 views

ArcGIS “Zoom to layer” scale

I'd like to quickly inspect the features in a feature class by double clicking the row in the table view and looking at the surrounding base layer. This works, but the feature fills the screen, so I ...
1
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1answer
71 views

How does the tolerance influence QgsGraphBuilder and tieing of points?

I am developing a script which uses OpenStreetMap data to calculate the distance (over the road network) between each building and the nearest hospital. To do this, I mainly follow the official ...
3
votes
2answers
192 views

Creating square buffer in qgis

How can I create a buffer with square ends along a line segment in qgis? I've buffered lines using v.buffer in the GRASS plugin, but the -c option for square ends is not exposed in that interface. ...
2
votes
0answers
65 views

Finding obstructions along a stream with LIDAR

I'm trying to find obstructions to boat traffic (downed trees, collapsed bridges, etc) along medium sized streams (5-15m across). The obstructions may or may not obstruct water flow. I have good ...
2
votes
1answer
132 views

GIS Analysis - best way to combine and display demographic data?

I am currently undertaking a demographic research project for my employer. We have the data on income, age, sex, language, transport etc and I have mapped most of it and created some thematics of said ...
3
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1answer
65 views

Analyzing spatial differences: conceptual and technical questions

My question is both conceptual and technical, but more conceptual than technical. It's a little long and multi-pronged, but I figured the best answers would consider everything, so thanks for bearing ...
16
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4answers
862 views

What are the benefits of hexagonal sampling polygons?

I am always on the lookout for useful methods to sample or partition study areas (usually in the form of raster datasets) into smaller units. Recently, I read an ESRI blog post about a new tool for ...
3
votes
1answer
80 views

Add more info in the attribute table after executing “Line intersection” in QGIS

I have executed the "Line intersection" tool on a road shapefile. This is under Vector > Analysis Tools > Line intersections. I get an output with attribute table having just two columns: type_1 ...
4
votes
2answers
437 views

What are some user-friendly GIS alternatives to Alteryx and ArcGIS?

I'm posting for some inspiration. At my last workplace we used Alteryx extensively for all data analysis, pumping out shapefiles which we'd then symbolise and output maps in ArcGIS. In my new ...
18
votes
7answers
6k views

Nearest neighbor between a point layer and a line layer

I've asked this question several times on stackoverflow and irc between #qgis and #postgis and I also tried to code it or implement it my self in postgis with no real answer. Using programming (most ...
5
votes
1answer
531 views

Split polylines at polygon boundaries in QGIS

I have a set of contour lines and a polygon set containing glaciers. Because I want the glaciers to have blue contours, I need to split the contour lines at the glacier boundaries. I can achieve this ...
-3
votes
2answers
93 views

How to get layer extension info via Arcpy

I want to get file format of a layer with using Arcpy. I am writing a tool that needs to take raster or feature extension like SHP, TIFF etc. Which functions should i use ? Note: I use ArcGIS 10
2
votes
6answers
225 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 ...
0
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0answers
82 views

Selecting ideal locations using vector data - location analysis ArcGIS

Wondering if I could get some advice on how to approach a problem. I have 10,000+ polygons of varying size and shapes which I would like to use in a location based analysis. I have a set of parameters ...
4
votes
1answer
187 views

What is the FME Equivalent to the ArcGIS Union tool?

I'm attempting to union 2 large featureclasses in ArcCatalog, QGIS, and FME. What is the transformer that would be equivalent to the ArcGIS Union tool?
9
votes
5answers
1k 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
193 views

GTOPO30 Slope analysis in ArcGIS 10.1 [duplicate]

Using surface - slope analysis tool box. All values for the slope calculation are in between 80 and 89. There are no values below 80. What am I doing wrong?
5
votes
4answers
3k 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 ...
2
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0answers
143 views

Our best table-analysis with GIS? [closed]

Sometimes I think about possible analysis using GIS models (I use QGIS 1.8), and I always think about few types of visualization techniques: demographics, traffic flows, distance ones... Thanks to ...
6
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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.
3
votes
1answer
694 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, ...