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.

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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
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1answer
242 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 ...
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2answers
191 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
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1answer
78 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
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1answer
422 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?
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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
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2answers
751 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
975 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
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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 ...
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1answer
140 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?
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2answers
557 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
187 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
355 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
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2answers
513 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
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1answer
403 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
626 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
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1answer
733 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 ...
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6answers
616 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
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2answers
436 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
90 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 ...
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0answers
283 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
312 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
323 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 ...
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vote
1answer
512 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
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2answers
397 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
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3answers
399 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
691 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
768 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
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5answers
1k 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
591 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
671 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
398 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
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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
678 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 ...
2
votes
1answer
180 views

Error in using/installing v.digit: GRASS GIS

When I wanted to edit a shapefile in GRASS I got this message: Unable to start wxGUI vector digitizer. Do you want to start TCL/TK digitizer (v.digit) instead? Details: No module named ...
1
vote
1answer
353 views

How to use r.patch with two maps having different colortables?

I am using r.patch to combine two raster maps in order to fill in the null values of the other. Is there a way to use r.patch but still maintaining the colortables of the separate raster maps? I do ...
0
votes
1answer
359 views

How to convert .ps to .png in a ps.map script?

I already managed to create a .ps file. How do I convert it to .png using a GRASS script?
4
votes
5answers
595 views

How to save a raster and vector into a single PNG file in GRASS?

I am trying to save a raster and vector into a PNG file. The vector is overlayed on top of the raster map. I was only able to save the raster file into a png using r.out.png but without the vector.
3
votes
1answer
485 views

spgrass6 and GIS_LOCK

I would like to thank's everyone first, i learn a lot here (gis.stackexchange) about GIS. I have one question about the use of GRASS within R session, i'm able to do some basic task, but i have one ...
5
votes
2answers
1k views

How to return raster values based on polygon (shapefile) boundaries in QGIS?

How to return raster values based on polygon (shapefile) boundaries in QGIS? Is this an elementary question, because I am finding it hard....... Ideally I would like a neat workflow as I am likely to ...
0
votes
1answer
114 views

d.legend script is not working

I'm using the d.legend script in grass but it is not working. I can only show/hide the legend using the 'add legend' option in the Map Display window in GRASS. I need to make d.legend script to work ...
0
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1answer
387 views

How to transform a DEM to a cartesian coordinate system?

I am using the script r.inund.fluv. I run the script with all the required parameters and it produced a lot or errors. I emailed the author of the script and he said that "I think you are not ...
6
votes
1answer
585 views

How to modify the colors of a raster map to use only one color in varying shades?

I have a raster map in GRASS containing elevation values. I want to display the elevation values in only one color (specificaly blue) but in varying shades of blue. I tried the options in r.colors, ...
4
votes
1answer
634 views

How to extract features from a vector layer?

I have a vector file containing the river lines of an area. I want to extract a specific water line from the vector. I used: v.db.select but it only displayed: ...
4
votes
2answers
643 views

Altitude Above channel in GRASS 6.4

i'm fairly new to the GIS world and GRASS (come from econometric background), i would like to do some species distribution modeling using R and GRASS. So i started to read the book of Tomislav Hengl ...
7
votes
1answer
398 views

Saving Command History/Outputs to a file - GRASS

Is there any way to save the commands typed and the outputs obtained in terminal under GRASS GIS to a text file? I have read that GRASS saves history for each mapset but I have no much idea about how ...