16
votes
5answers
9k views

Is it possible to make a DEM from contours in QGIS?

Is it possible to make a DEM from contours in QGIS? I have a shp file (contours) and their heights, can I use QGIS for produce a DEM without using GRASS? I find this creating a dem from contours but ...
7
votes
5answers
8k views

How to join multiple records to single feature?

apologies for what I'm guessing is a really easy problem to solve. GIS user, not programmer here. I'm trying to create a join/relate in QGIS where I have a shapefile of buildings and to that I would ...
5
votes
1answer
703 views

Raster incorrectly reprojected to OSGB(27700)

Ubuntu 12.04, QGIS 1.8.0, GDAL/OGR 1.7.3, GEOS 3.2.2 Open a Spatialite db with OS Mastermap poly layer (EPSG:27700); Add OpenLayers Plugin (1.0) from QGIS offical repository; Add a Google Satellite ...
59
votes
18answers
49k 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?
37
votes
21answers
44k views

Are there any free administrative boundaries available as shapefiles?

After learning about the US Census's TIGERLines datasets I'm addicted to GIS :) I've working with the following layers, from the USA data Country boundaries State boundaries County boundaries City ...
14
votes
3answers
2k views

Porting Avenue code for Producing Building Shadows to ArcPy/Python for ArcGIS Desktop?

Whuber provided an answer at Producing building shadows? which required using Avenue code. Any idea how to make it work in ArcGIS Desktop 10?
30
votes
6answers
9k views

How to use PostgreSQL/PostGIS with ArcGIS for Desktop?

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 ...
23
votes
10answers
43k views

How to convert MapInfo TAB and/or MIF to SHP using free tools or ArcGIS for Desktop core product?

How do I convert MapInfo TAB and/or MIF files to SHP using only free tools or ArcGIS itself? I've not had much luck trying to do this in the past and I don't want to have to shell out for the ArcGIS ...
10
votes
4answers
21k views

How to add a simple WFS layer from GeoServer to OpenLayers map?

I'm trying to add one of the included datasets with GeoServer to an OpenLayers map. I've followed the OpenGeo tutorials, seen similar thread on here, but I can't seem to crack it. Can somebody take a ...
16
votes
1answer
5k views

How to divide a polygon into specific sizes using ArcGIS?

I have several thousand irregularly shaped polygons in a shapefile. I want to be able to split each polygon into three areas, and to specify what the size of those areas (they sum to the previous ...
5
votes
3answers
2k 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 ...
8
votes
2answers
3k views

Cartographic techniques for symbolizing routing data

Some common problems with displaying routes created from street data, such as bus routes, include: Routes may overlap themselves, such as when a route takes the same road in opposite directions ...
11
votes
5answers
7k views

How to perform Raster Reclassification in QGIS?

Is there a way to do reclassify a raster image to Qgis? In Arcgis you can do that in Spatial analyst Tools→Reclass→Reclassify Any ideas?
9
votes
7answers
5k views

How to georeference a vector layer with control points?

I have a non-georeferenced vector layer that I need to be georeferenced. With raster layers the task is easy and straightforward, but I have no idea what should I do with my vector layer. I have a few ...
9
votes
5answers
8k views

Can QGIS read an ODBC connection?

I have a co-worker who manages a large MS Access database that contains X & Y fields for various locations he tracks. We have previously exported the data to CSV and used the QGIS Delimited Text ...
7
votes
2answers
2k views

QGIS display world country shape files centered on pacific ocean using Robinson, Miller Cylindrical or other projection

I wish to display a map in QGIS (world country shapefiles) showing all countries but centered on the Pacific area. I am not familiar with Proj4, so is there any way this can be done in QGIS please?
4
votes
2answers
495 views

Does Calculate Value (Model Only Tool) work correctly in tools run in Batch?

Am I correct that if my model has a model-only tool (Calculate Value), and then I run the model as a batched process, it will not run the Calculate Value expression? I wrote a model to upload, ...
4
votes
4answers
6k 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: ...
28
votes
4answers
4k views

Curved point-to-point “route maps”

I have recently been looking at airlines web pages that display their routes departing a certain city to all other cities they service. I would like to be able to create similar curved routes between ...
23
votes
2answers
2k 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 ...
16
votes
9answers
4k 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, ...
13
votes
9answers
16k views

How to convert KML to shapefile without losing attributes?

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 ...
22
votes
7answers
19k views

Removing small spaces (slivers) between polygons?

I have a set of polygons representing administrative districts. The districts were digitized by hand, and there are small spaces (slivers) between polygons where the polygons should be touching. How ...
20
votes
3answers
18k views

How to clip a raster with vector boundaries?

I am using QGIS. I would like to clip a raster precipitation layer using an admin boundary layer that is vector data. However the geoprocessing tools seem to be usable only for vector data. How can ...
15
votes
5answers
2k 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
9answers
23k 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.
21
votes
2answers
25k views

How to calculate polygon areas in QGIS?

Hi I would like to simply calculate areas of a area-shape file in square meters or in acres (ha). I didn't find that functionality in the vector tools. Could anyone here help me with that?
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 ...
7
votes
7answers
6k views

ogr2ogr convert all shapefiles in a directory

I have a directory with several shapefiles. How can convert all these shapefiles to MapInfo with ogr2ogr. I know how I can convert one file. And I can make a batch script writing a line for each file. ...
4
votes
2answers
6k views

Viewing .las format LIDAR data in QGIS?

Is there an easy path to visualizing this LIDAR data? I have QGIS, and some USGS LIDAR data in (.las) format downloaded from http://lidar.cr.usgs.gov/ . This means I have both the (.las) and ...
4
votes
1answer
4k views

Elseif Conditional Statement in QGIS Field Calculator

I am trying to write an ELSEIF conditional statement in QGIS Field Calculator (version 1.8.0). I have used an example I found online: CASE WHEN val < 0 THEN 'negative' WHEN val = 0 THEN ...
43
votes
4answers
12k views

Spatial clustering with PostGIS

I'm looking for spatial clustering algorithm for using it within PostGIS-enabled database for point features. I'm going to write plpgsql function that takes distance between points within the same ...
45
votes
20answers
12k 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?
30
votes
5answers
9k views

Comparison of the different open source GIS servers

I currently know the following open source GIS servers: Geoserver: java based, vector and bitmap support, also supports. Is now on par with mapserver (performance-wise). mapserver: c/c++, used to be ...
22
votes
9answers
4k 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. ...
30
votes
8answers
3k 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 ...
18
votes
6answers
9k 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 ...
26
votes
4answers
2k 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
2answers
9k 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?
34
votes
4answers
7k views

What are the pros and cons of PostGIS geography and geometry types?

My company uses geometry (the_geom) data type for storing geospatial data. I've recently been acquainted to the concept of geography (the_geog) data type which, as I understand it, stores the SRID ...
18
votes
4answers
6k 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, ...
14
votes
9answers
9k 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 ...
11
votes
4answers
1k 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 ...
34
votes
4answers
8k 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 ...
20
votes
1answer
14k 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 ...
19
votes
9answers
2k 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 ...
18
votes
3answers
29k views

How to merge multiple layers to one layer using QGIS?

I've imported several shapefiles which where exported from an Mapinfo .tab. Several tab files are imported resulting in 20+ layers. Afterwards I want to export it to geoJSON; but I'm reluctant for ...
17
votes
9answers
3k 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 ...
17
votes
9answers
8k views

How can I convert an excel file with x, y columns to a shapefile?

How can I convert an excel file with x, y columns to a point shapefile? There are some somewhat optional requirements in addition to the correct creation of a shapefile: Column types (as per ...
10
votes
4answers
4k views

How to create equidistant points in QGIS?

I am trying to create points (new layer) at specific distance along the road (existing layer) in QGIS. This gives solution for ArcGIS. How to achieve this in QGIS? This one explains how to create ...

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