GRASS GIS (Geographic Resources Analysis Support System) is a free, open source geographical information system (GIS) capable of handling raster, topological vector, image processing, and graphic data.

learn more… | top users | synonyms

5
votes
2answers
269 views

Can I split up v.in.ogr into multiple v.clean commands?

I'm trying to load a large set of polygons into GRASS with "v.in.ogr" and am running out of memory at the "Break Boundaries" stage. I'm wondering if I can break into steps all of the different things ...
7
votes
1answer
450 views

Why does GRASS eliminate polygons when using v.generalize?

I am facing a dilemma while trying to use v.generalize to simplify polygons which are similar in size and structure to US Counties or States. Often, I lose polygons from the data set after running ...
2
votes
0answers
117 views

How to fix Graphserver warning “osmdb has no edges!”?

I'm really new to GIS. I have some shapefiles data that I'm trying to import in graphserver. I'm doing: gs_osmdb_compile output3.osm output3.osmdb And the result is: WARNING: osmdb has no edges!. ...
3
votes
2answers
240 views

Hand fit curve and then apply to time series of rasters, make a map. How?

Maybe a data management problem, not too sure, but likely a challenge which someone has dealt with before. I have a time series of rasters. I can summarise the information by taking averages of each ...
4
votes
0answers
151 views

What open source solution would work best for auto extracting features from satellite images? [duplicate]

Possible Duplicate: Feature Extraction - Land cover I have been looking for an open source solution which would allow me to define a region (or collection of images) and extract features ...
1
vote
1answer
132 views

Blank Vector Selection Dropdown in QGIS GRASS Plugin

I realise there are some issues which getting vectors into the GRASS module in QGIS, but is the behaviour i am getting expected? I have loaded the vector shapefile via GRASS, closed G and reopened ...
5
votes
2answers
1k views

Quickly create contour polygons from cost points using OSS for web app

This is related to a previous question I've asked: Create filled contour map with GRASS I've created a point layer using OpenStreetMap data and pgRouting's driving_distance() function, where the ...
1
vote
2answers
91 views

v.dissolve (and other scripts) not in GRASS path

I see that I have the v.dissolve module in my grass64/scripts dir, but it is not found in my path from the GRASS command line. I have the GRASS_ADDON_PATH environment variable set: ...
5
votes
1answer
120 views

Would it be possible to construct a stand-alone grass.script python package?

I would like to migrate dependency on ArcPy to grass.script without requiring the full installation of Grass. Would it be technically possible to have a portable directory containing grass.script and ...
3
votes
2answers
711 views

How to combine polygons in a vector with GRASS?

I need to combine polygons of similar geological classes which are stored in a vector file called geology. I was looking for somethiing like "union selected features" or similar. In the GRASS Book ...
1
vote
1answer
225 views

How can GRASS export an .flt file?

I am using GRASS and connecting it to another application. The other application needs an FLT file of the raster map which I should export from GRASS. The other application only reads FLT files. Can ...
1
vote
1answer
104 views

How do I convert my coordinates to the limit of geographic region (outer edge)?

I am trying to use r.in.bin. The parameters of north, south, east, and west needs values: north=float Northern limit of geographic region (outer edge) south=float Southern limit of geographic region ...
5
votes
1answer
1k views

Create filled contour map with GRASS

Background I'm trying to make contour/isoline/isochrone maps to show what areas are within walking distance to schools for my pet project to help with the Safe Routes to School program. I followed ...
5
votes
1answer
238 views

Need to remove small areas, but only if they do not have adjoining boundary

I'm generalizing some lat/lon data in grass64 and as a precursor to the generalization, I am removing small areas from the data using 'v.clean'. The following command is working well: $ v.clean ...
1
vote
2answers
187 views

Can r.mask be called from a batch file?

I am using a shell script that is called by a batch file. The shell script contains the GRASS scripts that I am using for my program. Every time I use the r.mask script, it displays the error r.mask: ...
3
votes
1answer
74 views

Can two versions of GRASS be installed in a computer and still run independently?

GRASS 6.4.0 is currently installed in my computer. The script that I am trying to run is present in 6.4.1. It is stated in my previous post. If I installed 6.4.1, will my 6.4.0 still run? I don't want ...
3
votes
1answer
413 views

How to make a transparent background image using r.out.png?

Can the white background of the r.out.png of GRASS be changed to transparent?
22
votes
3answers
4k views

How to smooth a DEM?

I have a SRTM DEM and I want to create a shaded relief from it. I created the shaded relief in GRASS and the result is very nice, but a little rough becouse the area is near flat and the DEM is 90m in ...
8
votes
2answers
722 views

How to convert a vector boundary to a raster map?

I need to output a PNG file of a raster map overlayed with boundaries present in a vector map. The problem is, the r.out.png script only exports a raster map. My boundaries are in a vector format. ...
18
votes
5answers
935 views

How to simplify a routable network?

I have a network graph that I need to simplify in the sense of reducing the number of edges. The idea would be to merge nodes that are located close together and remove the connecting short edges. ...
6
votes
1answer
3k views

How to create a point along a line given distance

I have been given a non-spatial database which contains the names of lines which I have a shapefile for. The database also has names of points and the distance of each point from the origin along the ...
0
votes
1answer
135 views

Problem running i.gensigset in Grass. Any ideas?

It just returns ERROR: Unable to create signature file. It doesn't say why... Anyone had this before and found a solution?
1
vote
2answers
542 views

How to import .flt files into GRASS?

I am trying to import a raster file (.flt) into GRASS. The raster file (.flt) was generated from HEC-RAS. The said raster format cannot be imported into GRASS (it shows the error "file not ...
3
votes
2answers
185 views

Can GRASS v.net.iso split between nodes?

Can GRASS's v.net.iso module split networks between nodes on the network, i.e., if I am finding the area within a cost of 400, and there is a line segment with a cost of 800 leaving the center node, ...
3
votes
1answer
350 views

Standard Colors for Landcover Maps

I have classified Landsat images into five classes - A variety of Palm, Water bodies, built-up/open area, other vegetation and miscellaneous. I used GRASS GIS for the process and the final classified ...
4
votes
2answers
487 views

Monthly Average Solar Maps (R.Sun) in Grass

I'm trying to create monthly average maps as described in R.Sun in Grass. I have my DSM. In reading the page on OSGEO it mentions that it is possible without showing how. Ideas? I assume I will need ...
2
votes
1answer
395 views

Scripting in GRASS

Can anyone suggest me web-links to learn scripting in GRASS GIS (its utilities, examples etc.) other than those available in GRASS official Wiki/Sites?
2
votes
1answer
600 views

How to clean vector segment intersect errors in GRASS

I'm using GRASS to process a vector map. When I export back to .SHP and do a 'Check Geometry Validity' in Quantum GIS it lists several errors of this type... 3,segments 199 and 203 of line 0 ...
2
votes
1answer
726 views

How to handle multiple layers when importing a polygon shapefile into GRASS?

When I import a shapefile into GRASS, it seems to arrive as 3 layers. I.e. they appear in the qGIS toolbox browser as: myMap 0_polygon, myMap 1_polygon, myMap 2_polygon Is there a way to merge ...
4
votes
1answer
2k views

Convert shapefile lines to a polygon in GRASS

I have a shapefile of a map that is the outline of a number of islands. I would like to convert the lines into polygons (ie all islands filled in) using GRASS. I searched on how to do this with GRASS ...
5
votes
6answers
578 views

Southern hemisphere projections for Landsat upsets GRASS

Hi All does anyone have the last word on why Landsat scenes don't project in the southern hemisphere. This causes no end of trouble in GRASS, less so in QGIS. What I mean is, take an original scene ...
2
votes
2answers
419 views

Layer Stacking in GRASS

Similar to layer stack feature in ERDAS what functionality is available in GRASS. I am aware of r.composite, but it can accept only 3 layers. To obtain a stack of more than 3 layers what can be done?
2
votes
1answer
88 views

Can the concentration of values in a raster map be known?

I have a generated raster map containing different flood levels. Is there a grass script to determine the percentage of values in a raster map? I'm thinking of using r.mapcalc to solve this, but I'm ...
1
vote
0answers
278 views

gdal-grass plugin for gdal 1.8 [closed]

I'm facing a big issue...i moved from the ubuntugis version of grass to the svn one. I managed to compile the svn (releasebranche6.4) version nicely but i can't download the gdal-grass plugin for ...
2
votes
1answer
302 views

Command r.sunmask in GRASS

I have hypsometric model of relief, and I need to visualize shadows. I was suggested to use GRASS command r.sunmask, so I tried to set time values and run command, but it gives me an error "ERROR: ...
2
votes
1answer
321 views

Compilation of GRASS 6.4.trunk on Win7

you may have seen my other posts, at the point now where I am trying to use the landsat plugins in a lower version of GRASS. Markus N noted that the 6.4.2 might be better, since that is not out yet I ...
1
vote
1answer
489 views

Win7 GRASS 7 & i.landsat.toar

Hello has anyone got experience running i.landsat.toar ? The output files I get are empty, the command takes but a moment to complete. However when run in verbose mode all the calculations are done, ...
1
vote
2answers
395 views

GDAL-GRASS building fails

When I run ./configure --with-grass=/usr/local/grass-6.5.svn/ I get the following errors: .......... checking for gdal-config... /usr/bin/gdal-config using /usr/lib/gdalplugins as GDAL shared library ...
3
votes
1answer
195 views

SVN Version of GRASS and QGIS

I have GRASS6.5 SVN installed and wanted to go for SVN installation of Quantum GIS in Ubuntu 11.04. So as instructed in QGIS Wiki, I added the qgis repository to my sources.list file. Now I am able to ...
6
votes
3answers
388 views

Grass v.rast.stats returning null values

I have a vector layer (polygon) and a raster layer. The raster layer holds values for height above bald earth in a field called "value". I'd like the vector layer to inherit either the mean or the ...
3
votes
2answers
185 views

Is there a shortcut in GRASS for importing vector files?

Is there a keyboard or command shortcut in GRASS for importing vector files? If you know link where I can find maybe whole list of shortcuts for GRASS, that would be awesome. Thank you.
6
votes
2answers
672 views

What's a good toolchain to reproject some PNGs in plate carre to UTM?

I have some PNGs produced from Canadian DEM data. They're 1201px by 1201px heightmaps. Each one represents one quarter of a degree latitude and one quarter of a degree longitude. But I want to work ...
4
votes
4answers
1k views

Where can I find a tutorial for installing an addon to GRASS GIS that a six-year-old could understand?

I want to use the r.stream.distance addon in GRASS GIS 6.4 on ubuntu 10.04 (64 bit). I've installed grass from the repositories and that works fine but I can't seem to figure out how to install this ...
4
votes
1answer
746 views

How can I calculate the vertical distance to the nearest water?

Summary: I would like to create a raster where each cell contains the vertical distance to the nearest water (a decent approximation would be acceptable). The problem is that I'm not sure how to go ...
11
votes
5answers
975 views

Large shapefile to raster

I have a large shapefile (1 gb) and need to rasterise it. I have tried the following already. 1.) Import it into GRASS using v.in.ogr this failed with the error message: ERROR: G_realloc: unable to ...
8
votes
1answer
580 views

Kriging on GRASS+R

I'm trying to do a groundwater elevation map with an Ordinary Kriging on R, but always resulting on the lack of memory cannot allocate vector of size 146.5 Mb allocation (windows xp 32bit). ...
3
votes
3answers
654 views

How do I draw on a vector map in GRASS?

I have a vector map that has two lines. I want to have the two connected. Is there a way for me to draw a line to connect the two? I am using GRASS gis by the way. The two lines that I want to connect ...
3
votes
3answers
387 views

Can a raster map in GRASS be saved in JPEG/BMP format?

I'm trying to save a raster map in GRASS in jpeg/bmp format without using the GUI for d.out.file/d.save. Is there a script to do it? I tried r.out.gdal but it produced a map that is black and white.
13
votes
2answers
2k views

Is there a way to automate the preprocessing of LANDSAT data?

I'm currently enrolled in a remotesensing course, using LANDSAT data. Part of my course is about standardizing the scenes based on radiance values. I assume that because this is such a tedious task, ...
5
votes
2answers
655 views

Raster to Vector: Displaying classes in Vector Layer - GRASS GIS

I use Maximum Likelihood classification to classify Landsat image into two landuse classes - one of my interest and rest including all others. Inorder to assess the accuracy I export it in vector ...