3
votes
5answers
4k views

How to vary the transparency of symbols within a single layer in ArcMap?

I have a polygon layer which I am drawing in ArcMap using a graduated color symbology: Is it possible to vary the transparency between the classes, so that the transparency tapers off with the ...
6
votes
1answer
1k views

Adding Table to Layout View using ArcPy?

I am using ArcGIS 10.1 and I have a non-spatial table and some layers in a Data Frame. When I switch to Layout View I want to be able to show the map in a data frame element and the table in another ...
5
votes
2answers
2k views

How to automatically reload raster layers if source is changed in QGIS?

How to automatically reloaded raster layer if source is changed? (The path is the same but inside source file are changes) I use: qgis.utils.iface.mapCanvas().refresh() but layer not refresh. # ...
2
votes
2answers
2k views

Iterate through multiple Raster files and compute statistics using Zonal Statistics

I have a large number of raster images. What I'd like to do is to compute statistics on different sections of these raster files using a polygon. I think everyone is suggesting Zonal statistics. ...
1
vote
1answer
953 views

Apportion Neighborhood Information to Census Tracts

I have a shapefile of census tracts and another shapefile of "neighborhoods" with values that I need to have joined to the census tracts. I know I need to apportion the area of the neighborhood ...
42
votes
2answers
6k views

Acquiring ArcGIS-like speed in Postgis

I have been using Postgis 2.0 for 3/4 of a year now and while I really enjoy using it, excessive query processing time has rendered it basically unusable for my use case. I tend to do heavy ...
53
votes
19answers
36k views

What are some Free and Open Source GIS Desktop packages

Can someone please give me a list of free and open source GIS desktop packages?
53
votes
10answers
19k views

Creating drive time polygons using Open Source tools?

Is anyone using open source tools and/or data to generate drive time polygons that radiate out from a given location? For example, I have used ESRI products like Network Analyst and Business Analyst ...
23
votes
10answers
9k views

How do I develop my GIS programming skills?

I would like to develop my GIS programming skills, where do I start? People say learn C++ or Python but where can I learn this in a geographic context? Tutorials or anything would be very helpful, as ...
32
votes
8answers
5k views

Representation of network flows

This is a sample transportation network flow I've done a year ago based on 26 zones. For a project I'm working on now, I need to represent the flows over 1,000 zones with directionality. Any ...
39
votes
6answers
19k views

How to find the minimum-area-rectangle for given points?

The following is another problem that I am working on it these days. As you see in the figure, (BTW, I tried to make it self-presenter) the question is: How to find the minimum-area-rectangle (MAR) ...
20
votes
6answers
16k views

How to convert image of map into vector format?

What is the best way of converting a gif of a map into a vector format, such as a shapefile? The only relevant parts that I am interested in are the outline of the island so I realize some manual ...
19
votes
2answers
12k views

How to run a simple python script for QGIS from outside (e.g. Sublime Text)?

I would like to run a few small and simple python scripts for QGIS (Mac) from "outside" of QGIS. With outside I mean in this context, either the normal os command line (terminal.app) or even better, ...
17
votes
4answers
31k views

How do you decide what interpolation method to use for resampling raster data?

The question pretty much says it all; are there hard and fast rules about which interpolation methods are suited to each kind of raster data? Any Golden rules, rules of thumb? Good books or articles ...
16
votes
4answers
18k views

How can I install gdal 1.9.0 on my linux ubuntu server 10.04

apt-get install python-gdal installs version 1.6.0 and this is already installed. I would like to install the 1.9.0 version. Do I have to de-install 1.6.0 first and then compile manually or is there ...
19
votes
4answers
2k views

How do GIS web apps work?

I am completely new to GIS and therefore have questions regarding how the GIS Web development should be made, because the entire concept still confuses me. So, imagine I have a map. And by this, i ...
44
votes
4answers
15k views

LatLon or LonLat, what's the “right” way to display coordinates and inputs?

I'm trying to get a sense if this is an issue for others or every input/output should be labeled so user is not confused and just go with it? I think almost everyone pronounces it as "LatLon". Who ...
31
votes
2answers
17k views

How to change the SRID of exisisting data in PostGIS?

While importing my shapefile data to PostGIS, I did not select the proper Projection. How do I now change the SRID of the data, without transforming the Coordinates?
18
votes
2answers
4k views

How to make a separate Python installation that can call ArcGIS' arcpy?

I see a lot of threads asking how you can create a separate Python installation (e.g. the Anaconda or Python XY distribution) that can use arcpy, while not 'breaking' the original ArcGIS python ...
27
votes
4answers
4k views

How to use directional shading on boundaries for cartographic effect?

The attached screenshot of a National Geographic map shows some beautiful directional shading of boundaries. I'm trying to reproduce this sort of shading for a burn perimeter map, as I want to ...
22
votes
4answers
29k views

How do I load OSM vector data in QGIS 2.x?

In QGIS 1.8 I used the openstreetmap plugin to request data from the server, or open a .osm XML file, which produced 3 layers (polygons, polylines and points) in QGIS. This was great (give or take the ...
18
votes
4answers
7k views

How to join attributes from nearest point in QGIS?

I have two layers with points, call them A and B, each with different attributes. For each point in A I want to join all the attributes from the nearest point in B. Ideally this would also include ...
18
votes
9answers
16k views

How to convert ArcGIS Server JSON to GeoJSON?

I'm creating a web map using Leaflet, and I want to be able to grab feature layers from our ArcServer. I have successfully been able to retrieve a feature class as JSON, but Esri's JSON objects don't ...
15
votes
4answers
21k views

How to load external geojson file into leaflet map

I would like to load a geoJSON (polygon) file into my leaflet map. I have seen examples where geoJSON is embedded into the javascript code but I can't find any examples showing how it is done with an ...
10
votes
2answers
5k views
+200

How to calculate Network Service Areas in QGIS?

Is there any way in QGIS to apply service area buffers e.g if I have a point on a map I wish to show the service coverage of 1 mile, 2 mile, 3 mile, breaks using the road network?
23
votes
10answers
29k views

Adding Attribute data to shapefile?

I can display a shapefile in openlayers but I need to add some attribute data. I can open the dbf file in excel but there is no save as option in excel to the updated file as a dbf. What is the ...
22
votes
5answers
4k views

How to create regular point grid inside a polygon in Postgis?

How to create, inside a polygon, a regular grid of point spaced x,y in postgis? Like the example:
12
votes
3answers
5k views

Land Cover Feature Extraction from Satellite Imagery

I'm interested in a low-cost or open source solution for creating land cover GIS layers that utilize both spectral and textural extraction algorithms. I have used PCI Geomatica, ENVI, and Feature ...
11
votes
4answers
3k views

Simplifying polygons to linestring

I would like to simplify some polygons that represent rivers into linestrings. I assume that holes in polygons can be omitted. Anybody has some good idea how to simply do it? It would be nice, if it ...
27
votes
1answer
23k views

How to install a QGIS plugin when offline?

Due to various IT policies at my workplace, QGIS is installed on a machine that is not connected to the internet. I wish to install a couple of QGIS plugins on this system. I have downloaded the ...
22
votes
3answers
9k views

How to call gdal_translate from Python code?

Is it possible to use some gdal API to call gdal_translate from Python code? I do not mean simply executing the gdal_translate.exe from the file system, but rather call it somehow in code so I do not ...
10
votes
4answers
3k views

Connecting line features and determining the length of the longest line

I have a line feature (see image) representing a river that I created using the Stream_to_Feature tool. The attribute table contains several records representing different lines - the problem is the ...
13
votes
2answers
4k views

How to count and rasterize polygon overlaps in ArcGIS Desktop?

How do you take a vector layer with overlapping polygons and turn it into a raster where each cell counts the number of polygons containing that cell? We are looking at polygons of fire burn areas ...
21
votes
2answers
15k views

How to convert .shp into .gpx using QGIS?

I'm newbie using QGIS. I would like to convert .shp into .gpx. So, using Qgis, I open my shapefile and I tried to "save as" gpx but it gives an OGR error: creation of field ObjectId failed (OGR ...
21
votes
4answers
13k views

Joining non-spatial CSV file to spatial data (shapefile) using QGIS?

I have a CSV file which has postcode data in a field, but it is non-spatial e.g. no Easting and Northing. I have a shapefile with postcode in a field and some additional data. I want to join the ...
18
votes
9answers
5k views

GIS data for fast food industry

I am working a small project related to fast food industry. I am trying find GIS data for fast food chains like subway, MC Donald's, Arby's, etc in state of Ohio. Basically, I am looking for point ...
12
votes
4answers
3k views

Elevation profile 10 km each side of a line

How can I get an elevation profile for a band of terrain? The highest elevation within 10 km (on each side of the defined line) should be taken into account. I hope my question is clear. Thank you ...
12
votes
8answers
5k views

ArcObjects Resources [closed]

What are the best books/web sites for C# development with ArcObjects? The ArcGIS Resource Center is very helpful, but I am trying to find sources with more examples.
13
votes
2answers
2k views

How to reproject raster from 0 360 to -180 180 with cutting 180 meridian

I have a geotiff raster image that has a coordinate system with longtitudes from 0 to 360. The horizontal center of the image is 180 longtitude. See image below: I want to transform it to EPSG:4326 ...
9
votes
3answers
2k views

How to apply the four colors theorem in a polygon map in ArcGIS/ArcToolBox automatcally?

I need to apply the four colors theorem in a polygonal shape in a way that I do not need to choose manually each color to put in each region. I wish to knows if there is any extension, plug-in, script ...
7
votes
3answers
31k views

Basic If/Then in ArcGIS 10.2 Field Calculator (Python or VB)

I've been looking through these threads and can't seem to figure out my answer yet. Very new to VBA and Python, but lots of years with Arc.I know I can do this the slow way with Select By Attributes, ...
6
votes
5answers
5k views

How to calculate distances in a point sequence?

I'm looking for help calculating the distance between a sequence of points that are in a single Shapefile in QGIS. Below is what my data look like and a blank distance column I've added to show how ...
15
votes
4answers
2k views

algorithm to place maximum number of points within constrained area at a minimum spacing

I have a polygon layer that describes a constraint; I wish to add points within this area. I want to add as many points as possible, but they must have a minimum spacing between them. Is it possible ...
13
votes
3answers
5k views

How to programatically check for a mouse click in QGIS

I want to know how to check for a mouse click in QGIS. I am trying to write a python plugin and want to provide functionality similar to the "Select Single Feature" tool that already exists in QGIS. ...
9
votes
5answers
9k views

How to change the order of features in a shapefile?

I have a shapefile and I want to change the order of the features. Is that possible?
7
votes
6answers
6k views

How to fix quickly a lot of geometry validity errors in QGIS?

I am working on ownership data at a US county level. I have one shapefile per county that contains thousands of tax parcels. I need to dissolve the polygons representing parcels owned by the same ...
5
votes
1answer
522 views

Calculate population within radius

I have population data matched with polygons and a set of points that I have drawn buffers around. Assuming that the population within each geographical area, i.e. the polygons, is evenly distributed, ...
4
votes
2answers
855 views

Is Shooting Star broken in PGRouting 1.05?

I'm using pgrouting DLL 1.05 with postgresql 9.1. All required function installed. Astar and Dijkstra work fine with sample data but "SHOOTING STAR" is not considering "reverse_cost". Also if i try ...
15
votes
6answers
9k views

Recalculating full extent of File Geodatabase feature class?

I have a featureclass in an Esri file geodatabase. When I edit the features using the editor in ArcMap, and I delete most of my features and keeping only the ones in the middle, the zoom to layer ...
11
votes
3answers
7k views

Google Maps layer copyright popup every time map updated / user input

I have used a Google Maps hybrid layer in Openlayers in my HTML5 iOS app for months now and it worked perfectly. Just recently they changed something because the 'Map data...' line at the bottom looks ...

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