Tagged Questions

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

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7
votes
1answer
254 views

How to handle multiple map frames with different layers in one print layout?

Often I need two (or more) map frames in map layout to present different data next to each other. It is easy to make multiple map frames in QGIS Print Composer. BUT... It is in the nature of my work ...
7
votes
3answers
430 views

Does anyone know how to install the Orfeo Toolbox in QGIS?

I already tried this http://hg.orfeo-toolbox.org/OTB-Qgis-plugins/ repository and couldn't get it... This guy seems to have it: http://www.elance.com/samples/orfeo-toolbox-qgis/24111664/ Help, ...
7
votes
3answers
2k views

How To Convert A Set of ARC/Info ASCII .e00, .e01, .e02, etc Files Into .shp Files

I have a set files that I downloaded with extensions (.e00, .e01, .e02, etc). I have read that these are files used by ARC Info mainly, but I do not have ARC and nor am I really that interested in ...
7
votes
2answers
105 views

How to perform enhancement operations on an satellite imagery in QGIS?

I am a new user of QGIS please suggest how to perform image enhancement operations on an satellite imagery like ratioing, contrast stretching, edge engancement, filtering etc. in QGIS?
7
votes
1answer
151 views

How to migrate SVG-based styles for QGIS to other computers?

I'm working on a project that has involved creating many recolourable SVG icons and bringing them into QGIS. These are then used in layer symbologies, with these subsequent layer styles exported as ...
7
votes
1answer
868 views

Unable to Install External QGIS Plugins

I'm using: QGIS version 1.8.0-Lisboa on Windows XP, installed using OSGeo4W I am behind a proxy but I have configured it in Options > Network. When I go to Plugins > Fetch Python Plugins.. All of ...
7
votes
1answer
267 views

What is the best way to represent bridges using a point vector layer in QGIS?

I'm working on a hiking/biking maps of trails in the woods which sometimes have bridges that need to be shown on the map. I'm trying to figure out the best way to capture and represent them using QGIS ...
7
votes
1answer
307 views

What version of SVG should I be saving my images with for QGIS? Any particular options I should use/avoid?

I have a illustration in Adobe Illustrator that I'm trying to export as an SVG file and add to my map layout using the Print Composer of QGIS 1.7.3. When I add the image, I get strange artifacts that ...
7
votes
1answer
131 views

Why is QGIS 1.8 crashing when exporting to PDF?

I want to export for example this: but qgis crashes. Sometimes with an error message std::bad_alloc. But: My Mac has 8 GByte RAM and "just" 5,... something (of 8) GByte are used, moreover there is ...
7
votes
1answer
217 views

How to split two interscting polygons by the average linestring of the shared area (QGIS / python shapely)

I have two polygons, POLYGON((-5 -5,-5 5,5 5,5 -5,-5 -5)) POLYGON((1 1, 1 7, 7 7, 7 1, 1 1)) and wish to split them evenly. The result should be a split along the red marked line. I'm using ...
7
votes
1answer
155 views

Why is there a black hole in the Heatmap?

After running the Heatmap tool in QGIS I like to color the geoTiff according to my wishes. Using Psuedo color works fine, but it leaves me with no options, as type of color scheme or transparancy on ...
7
votes
1answer
208 views

How to rectify polygon-shapes in Quantum-GIS? [duplicate]

I have some polygon-shapes in qgis-1.7.0 and want to ensure that every polygon is a rectangle. See image below. Is there any way I can do this in quantum-gis (or any other f/oss)? Or how can I ...
7
votes
1answer
110 views

What constitutes a valid spatial layer when connecting QGIS to MySQL?

I'm trying to work with a MySQL 5.5 table using QGIS 1.8. I can do "Add Vector Layer", choose "Database", and successfully connect to the MySQL connection I previously set up. QGIS shows me a ...
7
votes
2answers
193 views

How to run a spatial query with a raster and vector layer in QGIS?

I have a soil map (vector-polygon layer) and a map of the crops farmed in the same area (raster layer, from the US Cropland Data Layer). I would like to calculate for a given soil type, the surface ...
7
votes
2answers
139 views

How to use Python modules as data providers in QGIS?

I don't know if it has been discussed in the past. Qgis data providers can only load native compiled libraries (.so, .dll, etc) that offer the required interface. Is there anything blocking to the ...
7
votes
0answers
64 views

How can I automatically split a spatial layer to a grid [duplicate]

Possible Duplicate: Divide vector in equal smaller parts in QGIS or similar I am a software engineer and the company I work for has a project that needs some spatial data manipulation in ...
7
votes
3answers
402 views

Creating regularly spaced, defined # of points within polygon in QGIS

I used the research tool "Regular Points" to produce a certain number of points within a polygon, but it forms a rectangular grid of points rather than only within the shape of the polygon. Since I ...
6
votes
4answers
353 views

How to use Z-Coordinate in QGIS?

I was mapping an area in Namibia and also tracked a lot of paths on my way with my Garmin device... so I thought it would be nice to see height differences in my area (esp. interesting in the ...
6
votes
5answers
2k views

How to load Shapefiles into a remote PostGIS db using command line?

Can we import a Shapefile from a system which doesn't have PostgreSQL installed (client machine) into a system having PostGIS installed? I am getting problem with 'shp2pgsql' and 'psql' since both ...
6
votes
4answers
202 views

How to map districts without showing features in other districts?

We want to have a map of each individual district, with the shops on it, so that the person responsible for each district can have a map of their territory. The reason I want to merge them is so that ...
6
votes
2answers
551 views

Is there a way to create a Personal Geodatabase in QGIS?

I believe I know the answer, but I wanted to ask. Is there a way to create a Personal Geodatabase in QGIS? I know QGIS can view Personal Geodatabases, but can one be created? I have a project where ...
6
votes
3answers
1k views

How to delete multiple selected polygons at once?

I'm new at this, a novice at best. I'm using QGIS 1.7.3. I simply want to select a large number of polygons on screen and hit the delete key to delete them and resave the shapefile. Can this be done?
6
votes
2answers
382 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 ...
6
votes
2answers
2k views

How to add Direction and Distance to attribute table?

anyone who can help. i just want to add direction (Bearing: i.e N 25 35 E) and Distance (Length: 125 meters) as my new field in polyline/line data. is there a plug-in to generate these fields? i tried ...
6
votes
6answers
2k views

Extract boundary from detailed layer in ArcGIS or QGIS

Is it possible to return the boundary (outside) permiter of a polygon layer? Let's say you have the map of the USA, for simplicity, broken down to the county level, is it possible to return the ...
6
votes
2answers
302 views

Can I install two versions of QGIS on the same computer?

I thought a few weeks ago someone asked a question about running multiple versions of qgis on the same computer. But I can't find it back.
6
votes
3answers
3k views

How can I join several raster files using QGIS?

I'm new to QGIS. How can I combine multiple raster layers into one layer? The raster images are of different areas with very little overlap. The goal is to bring numerous town plats into one project. ...
6
votes
2answers
417 views

Converting point sets to polygon boundaries

I'm trying to convert sets of points to their respective polygon boundaries. I think this is something like a Voronoi diagram or Convex Hull, but not quite. I'm sure there's a technical term for it, ...
6
votes
2answers
551 views

How to change null values raster values to 0 in QGIS?

I need help... I'm having problems with QGIS. I have some rasters that appear to have null values, even though I reclassified them to obtain a boolean raster :( How can I change the NULL values to 0?
6
votes
3answers
813 views

Are there any issues going back-and-forth between Quantum GIS and ESRI software?

A very simple question. I have very simple work tasks at the office (digitizing) that I would like to be able to work on at home because we are exceptionally busy. I don't want to spend thousands of ...
6
votes
1answer
96 views

How to save python session in QGIS?

After running a lot of scripts in QGIS' python console, I have more than 10 dictionaries and lists, and I need these for further analysis. Is there a way to save python session, with all these ...
6
votes
2answers
220 views

Why do my Shapefiles not align correctly?

First: I'll summarize what I understand so far so please confirm or correct me. When On-the-Fly is selected a layer is re-projected from that of the layer's CRS to that of the project CRS, IF ...
6
votes
4answers
415 views

Calculate polygon field based on neigboring polygon attribute

I have a vector shape with many different sized polygons each possessing an own class name (for instance "houses", "houses with offices", etc ...) I want to assign a new field to each polygon ...
6
votes
2answers
484 views

How do you calculate lat/lons from a PostGIS table which has a projected coordinate system?

I have a PostGIS table in a projected coordinate system (EPSG: 28355 or MGA94 Zone55). In QGIS (with the PostGIS manager plugin) I calculate a coordinate by performing the following SQL "UPDATE ...
6
votes
2answers
2k views

Derive WGS84 Longitude & Latitude from British Northings & Eastings

I'm looking for a fairly simple way to append columns with WGS84 longitude and latitude to a table containing northings and eastings. The source data is Ordnance Survey's CodePoint Open, which I is ...
6
votes
3answers
299 views

How to snap lines to points automatically?

I have two vector shapefiles: One file is points representing manholes and the other is a polyline file representing pipes leading to and from the manholes. I need to snap the lines within a ...
6
votes
3answers
217 views

assign and move centroids to their polygons

I m using QGIS 1.8 Lisboa. After calculating the centroids from a polygon shapefile, if some of them lie outside the polygon outlines, I'd like to move them on the polygon they came from. The ...
6
votes
2answers
193 views

Why is this spatialite polygon layer not displayed properly?

In QGIS, I have a spatialite multipolygon layer that have full objects in attribute table but do not display random ones as I scroll and pan around: Vietnam map at zoom level 1:16000000 - some ...
6
votes
3answers
271 views

How to extract area programmatically?

is there a possibility to extract the area covered by one geometry of a shapefile (polygon)? I tried with thepoly.area() but get "nan" as result. Ok. I think you are right and there is ...
6
votes
4answers
979 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 ...
6
votes
4answers
1k views

How to install “1-band color raster color table”?

I would like to use the "1-band raster colour table" extension. I'm using QGIS Wroclaw 1.7.4. In the plugin installer I can't find this extension, even I quote for third party extensions thing. Does ...
6
votes
1answer
811 views

How to split non-contiguous feature in QGIS?

I have a shapefile with a feature that is non-contiguous. I want to split the areas on the left from the area on the right. However, QGIS's Split Features tool requires you to draw a line over the ...
6
votes
5answers
4k 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 ...
6
votes
1answer
133 views

How to draw perpendicular lines in QGIS?

I have a situation like this: What I need to do is to connect each point to every line that is at most, let's say 200 m, away from the point. In other words, I need to draw a perpendicular line ...
6
votes
1answer
85 views

How to change all values in a field in one operation?

I am setting up a couple of shapefiles with text x, text y, text rotation and text size fields in order to utilize the labeling toolbar where I can move and rotate labels. I would like the values for ...
6
votes
2answers
380 views

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?
6
votes
1answer
838 views

Is there are QGIS plugin to allow the 3d visualisation of geological borehole data similar to the functionality of Target for ArcGIS?

I'm very new to QGIS, I have started using it as my new company is not willing to pay for ArcGIS and Target at this stage so I'm hoping QGIS can substitute not just in the interim but for good. What ...
6
votes
3answers
910 views

How to create a new Spatialite database in QGIS

I've been trying to create a new spatialite database within QGIS 1.8 (SpatiaLite Version 3.0.1; QSpatialite 6.0.3) and keep getting this error: "The SQL query seems to be invalid. no such table: ...
6
votes
1answer
317 views

How to add a toolbar via python?

Through tutorials I learned how to add a toolbutton to the plugins-toolbar via python. Now I wonder how to add a complete toolbar with toolbarbuttons via python. Can anybody give some example-code? ...
6
votes
2answers
1k views

How to use Heatmap plugin and its output?

I have a layer of points which I would like to depicted as a heatmap concentration of points for visualization. In QGIS 1.8 I tried the built-in heat map plugin, leaving the default values as is, and ...

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