28
votes
10answers
9k views

Seeking options for Spatial ETL (Extract, Transform, Load)?

I am interested in the pro's and con's of various spatial ETL (extract, transform, load) tools. If you have used the items listed here (or add your own), please share your opinions and experiences. ...
60
votes
7answers
83k views

What is the difference between DEM, DSM and DTM?

I am listing some of the acronyms used in our work and had to stop to think about whether to list these together or separately: DEM: Digital Elevation Model DSM: Digital Surface Model DTM: Digital ...
21
votes
9answers
31k views

How to convert KML to shapefile without losing attributes using QGIS?

I'm new to QGIS and all geoinformation itself but have to work on some difficult stuff. I have a KML file with hundreds of points. To each point there is information, such as Name, Power, Age (it's a ...
30
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
5answers
22k views

Creating Centrelines from Road Polygons/Casings?

I want to create center lines from road polygons. Are there any automated tools in ArcGIS for Desktop to do this? I am including a Screenshot of my vector file below.
11
votes
1answer
11k views

How do I calculate the latitude and longitude of points using QGIS?

I'm trying to figure out how to calculate the lat/long of points using the QGIS field calculator. Is there an easy way to do this? I saw a previous related question, but it deals with a more advanced ...
35
votes
6answers
17k views

How to use PostgreSQL/PostGIS with ArcGIS for Desktop? [duplicate]

Has anyone used PostgreSQL with PostGIS successfully? I am a semi-experienced ArcGIS user and want to build out a database and connect it to ArcCatalog. I've scoured the internet for resources but ...
28
votes
4answers
8k views

Separate polygons based on intersection using PostGIS

I have a PostGIS table of polygons where some intersect with one another. This is what I'm trying to do: For a given polygon selected by id, give me all of the polygons that intersect. Basically, ...
20
votes
11answers
4k views

Discontinuous or Interrupted map projections?

Do any of the current open source GIS softwares support discontinous projection systems? E.g. sinusoidal, dymaxion, butterfly, etc? If not, are there any affordable commercial ones that do (affordable ...
9
votes
6answers
5k views

Get a point on a polyline from end points given distance along poly line

I have start point and end point of a polyline. How can I get a point on that polyline from end points specified by the given distance. How can I get this by using arcpy provided that this script ...
12
votes
8answers
13k views

Extract raster values at points

How can I extract values from a raster by points. I prefer not in Arcgis. I prefer in Qgis or Mapwindow or other open source gis.
13
votes
3answers
6k 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. ...
13
votes
5answers
7k views

Is it possible to export geospatial PDF from QGIS via GDAL/OGR? [duplicate]

Is there any plugin for QGIS which would help me in exporting the map document as a geospatial PDF (similar to Terrago's GeoPDF)?
8
votes
2answers
10k views

ECW for QGIS 1.8 in Ubuntu 12.04

I have followed various online help guides on how to make ecw for QGIS 1.8 work in Ubuntu 12.04. I had it all working in Ubuntu 10.04 but since migration to 12.04 no such luck. Is there a guide that ...
5
votes
3answers
3k views

Python, comtypes and ArcObjects: Error creating AppROT object

I am experimenting with comtypes and ArcObjects under Python 2.6.5 and ArcGIS 10 SP1. I'm using the pure Python method to wrap the ArcObjects OLBs described in this answer, but getting an error in the ...
12
votes
3answers
13k views

Converting Polygon into single or all Points using QGIS?

I want to convert polygons into points using QGIS. I know how it's done in ArcGIS Desktop.
5
votes
5answers
6k 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 ...
2
votes
3answers
7k views

How to auto increment a field in a feature class?

So I'm relatively new to ArcGIS and ArcCatalog. I have created a field name of PROJECTID in a feature class in a Personal Geodatabase. The data type is TEXT. This will be a ten digit ID. The first ...
2
votes
3answers
3k views

Local Coordinate to Geocentric

The ultimate question, I need a transformation matrix to take a point in local space representing a roughly 500m x 500m place in New Mexico centered at -108.619987456 long 36.234600064 lat. The final ...
2
votes
2answers
3k 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. ...
72
votes
11answers
23k views

What Makes a Map be classed as Badly Designed?

A poorly designed map can not only look visually unappealing, but can convey the wrong message, which could lead to bad decisions being made. I would like to ask people to post examples (that are in ...
20
votes
4answers
37k 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 ...
18
votes
4answers
20k 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 ...
33
votes
2answers
20k 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?
25
votes
6answers
24k views

Trilateration using 3 latitude and longitude points, and 3 distances

I want to find out an unknown target location (latitude and longitude co-ordinates). There are 3 known points (latitude and longitude co-ordinate pairs) and for each point a distance in kilometers to ...
23
votes
12answers
24k views

Bulk Geocode 20 million records

Are there any free or reasonably priced databases for the US which can be searched and return latitude and longitude information?
30
votes
3answers
3k views

How to represent trend over time?

I have a time series of rasters where the cells of each raster represents some value at a certain time. I'd like to generate a map that highlights the magnitude of positive or negative trends in this ...
24
votes
9answers
18k 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 ...
19
votes
4answers
8k views

Joining 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 ...
23
votes
9answers
53k views

How to import a DWG into a QGIS project?

I have a lot of DWG files like base map, and water and wastewater network. I am lookin for the principal steps to import my files into my QGIS project.
16
votes
4answers
2k views

How can I generate irregular grid containing minimum n points?

Given a large (~ 1 million) sample of unevenly distributed points - is it possible to generate irregular grid (in size, but could also be irregular in shape if that is possible?) that will contain ...
35
votes
3answers
16k views

How to make a spatial view in PostGIS and add it as a layer in QGIS?

In PostGIS 2.0, what is the most efficient way to create a spatially enabled view that is viewable in QGIS? I followed the context of Part 2 of @Mike Toews answer to this question, and the view ...
19
votes
6answers
4k views

How to make a GIS inventory?

My office will be seeing a big change in its GIS section. This section has been operational since the 1980's and has a huge collection of GIS data (i.e., shapefiles, raster files, data, etc) but never ...
14
votes
2answers
3k 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 ...
10
votes
6answers
6k views

How to get “.GDB” Esri File Geodatabase in QGIS for MAC OSX 10.6?

I understand there are programs like OSGeo4W that allow windows users to work with File Geodatabases, but is there something similar for Mac OSX?
4
votes
2answers
3k views

How to install 3rd party python libraries for QGIS on Windows?

How can I use 3rd party libraries on QGIS plugins on Windows? I've developed a plugin that uses rasterio and numpy for a customer, but he's having problems installing rasterio and numpy. Actually ...
15
votes
4answers
32k views

How to convert a vector layer to raster?

In qgis in the raster menu there is an item "convert vector to raster". This behaves strangely - I do not understand how it is supposed to work. I can select a vector file, an attribute and an ...
6
votes
5answers
2k views

How to Digitize Free Satellite Imagery in QGIS - Alignment issues with Openlayers Plugin

I am trying to digitize OpenLayers data (such as Google satellite imagery) with no success. Whenever I try to move or zoom the canvas the vector layer I digitized loses the position relative to the ...
4
votes
4answers
7k views

Problems with OpenLayers and WFS - proxy.cgi issues

I am having problems getting WFS data to display on a map using OpenLayers/GeoExt/GeoServer. I created a proxy script like on this page: http://trac.osgeo.org/openlayers/browser/trunk/openlayers/...
1
vote
1answer
271 views

Graph/Network building and analysis of linked polygons in ArcGIS for Desktop?

This is more of a follow-up question to Divide polygons into *n* number of groups of equal counts with ArcGIS 10.2 and grouping village points based on distance and population size, particularly the ...
6
votes
1answer
2k 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
4answers
3k views

Cannot see OpenLayers under Plugin in QGIS?

Although I have installed the OpenLayers plugin in QGIS 2.4, I cannot see it in the list when I click on Plugins. Does anyone else have this issue?
64
votes
18answers
80k views

List of GIS applications for Android Tablets

I know that ArcGIS will someday be available for Android, but does anyone know of any other GIS apps that are available for Android tablets?
48
votes
2answers
7k 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 ...
55
votes
11answers
22k 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 ...
40
votes
4answers
7k views

Debugging ArcPy scripts?

I have written many Python scripts using ArcPy in ArcGIS 10, and so far my only means of debugging is restricted to printing messages to the geoprocessing results window using arcpy.AddMessage(). ...
34
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 ...
19
votes
3answers
6k views

How to perform Random Forest land classification?

This is a follow-up to a previous post: Machine Learning Algorithms for Land Classification. It seems that the Random Forest (RF) classification method is gaining much momentum in the remote ...
31
votes
11answers
19k views

How to connect to PostGIS database from ArcMap?

How can I connect to a PostGIS database from ArcMap? Solutions for ArcGIS 9.3, 10.0 and later are acceptable. Ideally, I would like to be able to perform spatially enabled queries and receive the ...
18
votes
10answers
6k views

Getting started with ArcObjects?

What is the best route or place to get started with ArcObjects if one is not a developer and not aiming to become a developer? I've been using gis professionally for a long time, almost two decades, ...

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