Tagged Questions

Quantum GIS is a user-friendly, cross-platform GIS application licensed under the GNU General Public License.

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16
votes
0answers
297 views

What does the adoption of Python by NVIDIA for GPGPU mean for GIS?

Today NVIDIA announced support for the Python language on its flavor of GPGPU (CUDA). Manifold GIS uses CUDA to enable some accelerated raster operations but it is not a programmable environment and ...
11
votes
0answers
247 views

Python Plugin Development in QGIS: How to access label text?

I'm trying to create some custom labels for point features in a QGIS point vector layer, and I want to write a python plugin to do it. We need our labels to be presented with color tinted rectangles ...
8
votes
0answers
419 views

Ordnance Survey OpenSpace in QGIS

The version of gvSIG that I have on my Android tablet will load OS OpenSpace layers and I wonder whether or not it would be possible for QGIS desktop to do the same? And if so, how? I have my own ...
5
votes
0answers
92 views

Moving points onto lines (~neighborhood)

I do have two vector layer, of which one is a point layer based on "events" by remote sensing and the second one is a line layer from local research. In my case these are earthquakes and tectonic ...
5
votes
0answers
72 views

How to sample a 3D raster along a 3D path (or 4D raster along 4D path)?

I have a 3d raster dataset of atmospheric variables (lat x lon x altitude). I would like to sample this raster dataset along a 3d path. Any idea how I can achieve this, preferable with qgis or ...
4
votes
0answers
50 views

Is there an Attribute Table Feature limit?

I am copying a table with 11,000+ features but only about 700 show up on the QGIS attribute table. Is there a limit? how can I avoid this problem? Thank You in advance!
4
votes
0answers
48 views

Can I edit shapefile while using a definition query in QGIS?

Is it possible to edit shapes while using a "definition query" or "query builder" in QGIS? I'm trying to do this in the same way I used to in ArcGIS. Thanks!
4
votes
0answers
75 views

Modifying File GDB Feature Class Features Using QGIS

I've installed the File GDB API using the OSGEO4W advanced installation when installing QGIS. I've had a bit of trouble with it initially and have posted a few questions with some helpful Stack ...
4
votes
0answers
65 views

Previewing File Geodatabase in QGIS Browser - Is it Possible?

Can I Preview/look at file geodatabase attributes in the QGIS browser if I have installed QGIS using OSGEO4W installer and FileGDB API? Currently I can add/edit file geodatabase feature classes to ...
4
votes
0answers
84 views

How to combine stacked polygons within a shapefile?

The image below shows my shp-file. Every polygon has the same transparent color. So a darker blue means, that several polygons are stacked! How do I cut every polygon with each other so no polygons ...
4
votes
0answers
73 views

How to include streaming media into an OpenGeo system to monitor live-tracked animals?

I am wondering how to include streaming media (video), or camera feeds, into an OpenGeo system to monitor live-tracked animals. I am currently doing so with different applications, but I want to do ...
4
votes
0answers
84 views

How to Perform a Grouping Analysis of Points to Divide a Polygon into n Number of Sub-Regions?

I'm attempting to create n sub-regions from a polygon based on a cluster analysis of a bunch of overlapping raster layers (physical layers, eg. depth, currents, waves...). Briefly, I can create a ...
4
votes
0answers
126 views

How to create svg symbols that have modifiable fill color, stroke color and stroke width?

I want to create some svg symbols for Qgis using Inkscape, those symbols must have attributes as described in the question. For the last two days, I have been experimenting as instructed by Sourcepole ...
4
votes
0answers
186 views

How can I improve my Georeferencing results?

Background This is my second question related to georeferencing naked raster maps in order to re-visualize them on different coordinate systems and in conjunction with other data layers. The previous ...
4
votes
0answers
94 views

Problem opening a shp in another application

I helped a colleague converting waypoints from a gpx file to a shape file. My colleague has only arcMap. I gave him the shp and when he opened it in ArcMap, it did not show anything in the attribute ...
4
votes
0answers
195 views

mdb geodatabases in QGIS for MAC

Good afternoon, I've been unsuccessfully looking for a way to add data from a .mdb geodatabase into QGIS for mac. Using the add vector layer, .mdb is not available in the filetypes, and in the ...
4
votes
0answers
158 views

How to automatically format the legend labels? in QGIS

I have to do 10 maps (for a start) with "style" -> "graduate" with quantile mode. I need to format the label of the different ranges so that the legend looks comprehensible: Instead of having 1.0000 ...
4
votes
0answers
365 views

Does QGIS have these CAD editing functions?

I tried QGIS for the fist time today and it seems quite capable for the task that I have in mind. However, I really miss some basic editing functionality from another GIS software that I have to use ...
4
votes
0answers
403 views

How to get rpy2 for QGIS on OSX?

I am a new QGIS user, have installed QGIS on a Mac running Snow Leopard OSX 10.6.8 following all the instructions. QGIS seems to work well for everything other than when I boot up I get the message ...
4
votes
0answers
682 views

Union, Dissolve, Buffer — multiple layers, all in one step?

I'm a new user of Quantum GIS (1.7.3) and I need to repeat a task multiple times, so I'm wondering if there is a quicker way to do the following (with three or more polygon layers - each layer has a ...
3
votes
0answers
23 views

Why are there changes in location when printing inserted points?

Añadí una capa de texto delimitado por comas y luego agregue una imagen satelital de google earth. Realizo un diseño de impresión y al imprimir cambia la ubicación de los puntos en varios metros. Cual ...
3
votes
0answers
49 views

Masking/removing polygons from shapefile

I have a shapefile containing the road traffic noise of a city. The shapefile has 5 columns, where 'noise_in' (noise interval) ranging from 1-5 is included. I want to remove/mask the road noise from ...
3
votes
0answers
42 views

Can layers from Spatialite db be used as input for a Sextante model?

I'm trying to build my first models in SEXTANTE and already fail at the start. It seems not to be possible to add a vector layer which derives from a database. Orginally, the layers are from a .mdb. I ...
3
votes
0answers
67 views

How to access and/or manipulate table data in QGIS composer label?

When setting up a map to print using the QGIS Composer, how can I insert a label linked to a specific table record? I have been using the latest development build (1.9.0) which has the new Expression ...
3
votes
0answers
96 views

How to customize label color in QGIS: Data defined label settings? Expressions? Both? What are the steps?

Updated to show more current screenshot and clarified the question (Which tools? What are the steps?) I'm learning QGIS (1.8 "Lisboa" for Mac). On the QGIS Layer labeling Settings window there is a ...
3
votes
0answers
46 views

QGIS Workflow Problem

I have 3 SpatiaLite layers (one without geometry but with fields that need to be filtered, one with points and one with polygons, both without any non-geometry fields) that need to be combined to a ...
3
votes
0answers
79 views

How does Zonal statistics handle pixels that are on the border of the polygon?

I am using the plugin zonal statistics to calculate the sum of the raster cells within polygons. How does this plugin handle pixels that are on the border of the polygon, are those cell values ...
3
votes
0answers
154 views

Polygonize vegetation area from Landsat7 RGB using QGis / Bilko?

I'm trying to extract the areas with vegetation as a polygon-shape from a landsat7-image, 30m resolution, RGB, using QGis 1.8 or Bilko or (hopefully in the near future) ArcGIS. The area is in Northern ...
3
votes
0answers
172 views

How to make working with Postgis vector layers in Qgis faster?

I have just imported a Spatialite database into Postgresql/Postgis. The problem is: using Qgis to work with them is much slower in Postgis (spatial indexes created) than doing the same in Spatialite. ...
3
votes
0answers
74 views

Why doesn't Polygonizer copy the line ids to my polygonized shapefile?

I am trying to convert a line shapefile into a polygon shapefile using Polygonizer plugin, and when my new polygons are created all the cells in my id field are "Null", although I have clicked "copy ...
3
votes
0answers
50 views

Detect connections along shapefile in QGIS?

I have a set of polylines and a set of points that lie along or very near to the polylines, and I need a way to measure which points are connected to each other along the polylines, and what the ...
3
votes
0answers
92 views

QGIS: GPS Tracking with improved Altitude

I am preparing for archeological fieldwork in Sudan. I recently came up with RTK equipment and software using RTKlib to export the real time corrected data (cm level) to QGIS via a simulated NMEA ...
3
votes
0answers
116 views

Exporting 3D geometry from PostGIS 2.0

I have a table containing 3D geometry in a PostGIS 2.0 database (the geometry is of type LINESTRING Z). I need to get the geometry out and into a DXF, DGN or 3D Shapefile. What is the easiest way to ...
3
votes
0answers
97 views

How do I access layer attributes from within QGIS' manageR plugin?

This is probably a fairly basic question, but searches for manageR come up with a lot of noise, and there's no manageR tag. What I'd like to do is load the attributes from a particular field of a ...
3
votes
0answers
138 views

How to symbolize vector features using RGB values stored in three fields?

I need to symbolize a vector layer in Arcmap based on RGB (or HSB - can do either) values found in fields in the attribute table. I'm working with up to 10 different datasets, each with over 100 ...
3
votes
0answers
48 views

Why are selected features not highlighted in OSM layers?

I am experienced with GIS, but new to QGIS and Opensource data. I recently opened an Open Street Map (osm) file in QGIS 1.8 (on Kubuntu 12.04). I found that when I selected a feature, there was no ...
3
votes
0answers
128 views

What to do about Geoserver WPS Warning “Could not get a ServiceInfo”?

This is the warning i am getting when i try to use this WPS service from QGIS, and the processing take a long time, but doesn't terminate, what might be the problem? 17 Oct 12:33:25 INFO ...
3
votes
0answers
173 views

How to access tiles in Tilecache using QGIS?

I've Mapserver set up with a mapfile that points to a tileindex. In QGIS I can call the mapfile and view the rasters dynamically. I've got access to tilecache and I've seeded the same mapfile/rasters ...
3
votes
0answers
126 views

How to create unfilled circles (style) for point layers?

I have a point layer and want to visualize it with unfilled circles. It is only possible to change the colors and size of the symbology layer (single mark). But I would like to change the filled ...
3
votes
0answers
237 views

How to offset points along line in QGIS?

I used the "Profile from Line" plugin to create evenly spaced points along a line in QGIS, but I'd like to offset them to either side of the line. I spose I could draw two lines parallel to the ...
3
votes
0answers
392 views

How to find all intersections and count lines arriving at each intersection?

I'm having a hard time getting off the ground with this, and am trying to move away from ArcGIS / arcpy. I have a shapefile with a network of polylines. I want to find/count all 2-way intersections, ...
3
votes
0answers
210 views

MapServer WMS feed and QGIS

I've managed to create a WMS feed from Mapserver showing a tileindex to some rasters and a shapefile and it appears in my browser OK. If I go to QGIS (1.8.0 Windows StandAlone) and I connect to my WMS ...
3
votes
0answers
174 views

Why do our .shx files disappear?

We are using QGIS in our workgroup, and have recently updated to 1.8.0 Lisboa. To share our file structure we are using egnyte similar to dropbox. We all use Mac OS, and have used QGIS for years, ...
3
votes
0answers
274 views

How to reverse-georeference with QGIS?

I have a map with a "strange" projection (it's basically hand-painted, not an exact one). I can easily georeference it in QGIS using the Georeferencer plugin and the Thin Plate Spline transformation ...
3
votes
0answers
546 views

How to create point labels from midpoints of road polylines in QGIS?

Heres what i want to achieve: i have a roading polyline layer (singlepart ie has several features per road, grouped by an id field), and i want to (after merging the parts) find the mid point of the ...
2
votes
0answers
45 views

“Map 1” vs “Map 0”

When I compose a map to print, and get everything all set; then close it for some reason; then reopen it--the scale bar appears messed up. I then go to the Scale Bar settings, and find that under ...
2
votes
0answers
63 views

ArcGIS Raster Calculator VS QGIS Raster Calculator

Are there any major differences between ArcGIS Raster Calculator and QGIS Raster Calculator?
2
votes
0answers
46 views

Installing knn on PostgreSQL for windows

I am trying to install the extension KNN for clustering as an extension on my PostgreSQL database. I have downloaded the file http://www.pgxn.org/tag/analysis I found instructions on how to ...
2
votes
0answers
55 views

How to create stacked bar/column charts in QGIS?

I know that conventional bar charts (with the bars adjacent to each other) based on feature attributes can be plotted in QGIS. But can you please tell me if there's any way to plot the bars in the ...
2
votes
0answers
29 views

qgis missing menu bar ver 1.8.0-lisboa on ubuntu linux

QGIS emits the following warnings when starting, and fails to display the main menu bar. $ qgis --nocustomization Warning: loading of qgis translation failed [/usr/share/qgis/i18n//qgis_en_US] ...

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