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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1answer
36 views

Why there is no “View Output” button for the command “v.to.points” in Grass plugin in QGIS?

How do i get or where do i get my output vector point layer after i run the command v.to.points to my vector line layer?
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31 views

Extracting distances along a line from postcode a centroid to the nearest point (bus stop)

I'm looking to measure the distance from postcode centroids (point file) in a city to the nearest bus stop (point file) along the road network (line file). In Qgis I can calculate the distance but ...
2
votes
1answer
39 views

Matching raster regional extent with vector region in GRASS?

In Grass GIS, I am able to import bathymetry .tif raster data however the region coordinates are not in lat/lon formar and therefore, do not overlay with my vector points which are in lat/lon format. ...
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36 views

GRASS: Site Analysis using address lists in vector maps

My objective is to analyze and optimize the distribution of sites (e.g. shops) in a certain area.In the end I want to be able to answer questions such as: How much farther or less will customers ...
1
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1answer
373 views

How do I install qgis lyon with grass access

I am working wit a win10 64 bits 16mb of ram. I want to install Lyon on my computer and not get rid of 2.83. My 2.83 is a stand allone install. I thought I could install Lyon usion OSGEO 4w installer. ...
6
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2answers
248 views

Skeletonize vectors in QGIS/Python

I am trying to find a tool to create a skeleton of a large vector dataset using QGIS and its bundle. It should be directly programmatically callable through Python or commandline (QGIS, GRASS, OGR ...
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0answers
46 views

G_Malloc error for Grass module(r.stream.extract) in R

I am having a big issue of this G_malloc Error while using a module of Grass (6.4.4) (r.stream.extract) in R. Initially I thought my computers configuration was low, So I switched to 8gb Ram 64-bit ...
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0answers
94 views

QGIS Training Manual - Lesson 12.2.1 (GRASS GIS) - r.colors.table module does not color raster

I am going through the QGIS Training Manual, Lesson 12.2.1 ("Follow Along: Set Raster Colors) and noticed that the 'r.colors.table' GRASS module did not color my DEM raster layer which I imported via ...
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2answers
125 views

Tool or program to clean polygon dataset

I have a polygon dataset (shapefile, mapinfo tab file) which I would like to "clean" to be topologically correct. The polygons are assigned an ID which represents a specific class. For example ID 3 is ...
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0answers
27 views

Best way to store, elaborate and query raster data [closed]

I have created multiple raster images with GRASS-GIS (~150Gb), that I'll need to multiply for a certain coefficient, and query the results that need to by saved just temporally. The portions of the ...
4
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2answers
709 views

Is it possible to produce a decent looking shaded-relief map at 50K-scale-or-larger using SRTM3 DEM?

I'm trying to make a decent-looking shaded-relief map of a particular area in 50K-scale-or-larger using open-source tools. The best (and free) option I have for DEM data for that area right now is the ...
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0answers
28 views

Raster statistics change after re-projection — which one is correct

I'm looking into some global DEMs (like ETOPO1 - http://www.ngdc.noaa.gov/mgg/global/global.html), and noticed that the statistics for the elevation values can change quite a bit after reprojecting ...
2
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0answers
36 views

QGIS - WHERE SQL within a processing.runalg statement for v.surf.rst in python console

I'm creating lots of raster files with grass:v.surf.rst so rather than using the graphical interface I wanted to use the python console (and potentially put in in a script at some point). However ...
0
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0answers
21 views

TIF file is black in GRASS when imported

I'm trying to input a TIF file into GRASS. Dimensions: 11617 x 15489 Size: 514 mb Color Palette: 2 colors (black background, white polygons). Layers: one layer Compression: none Software used for ...
2
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2answers
107 views

Points that get created in the wrong order when using e.g. QChainage?

I have a polyline layer (road) that I want to use to get a point layer with 1 km between the points. I have tried both 'QChainage' and 'Locate points along lines' to do this. They both work, I get ...
0
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1answer
98 views

Determination of Soil Moisture for a Region Using open Source Data

I want to derive soil Moisture for a region using Landsat and Microwave data could you please help me with the procedure.
1
vote
1answer
762 views

How to fix the grass7 package available from the ubuntugis-unstable PPA?

Out of the blue, grass stopped functioning this morning on one of the Ubuntu 14.04 systems I use: $ grass Starting GRASS GIS... python: can't open file '/usr/lib/grass70/gui/wxpython/gis_set.py': ...
3
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1answer
269 views

QGIS 2.10 with ubuntugis dependecies Grass issues Ubuntu 14.04

I saw in How to correctly install QGIS 2.8.3 with GRASS plugin on Ubuntu 14.04? how to get Qgis 2.10 running from the non ubuntugis repository with grass features but I'm still having problems with ...
2
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0answers
256 views

GRASS v.overlay.or Error when trying to split a polygon with a line

I am using the Grass plugin in QGIS for Windows (1.8.0). I am trying to split a polygon with a line feature. I am using the v.overlay.or function within the QGIS Grass plugin. I have the line layer ...
1
vote
1answer
67 views

Reading files from grass into R with loop

I have a connection between GrassGIS and R. I want to read thousands files from my mapset into R. I have lines with names "line1","line2"... I know I have to use a loop for this so I did ...
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0answers
39 views

Multiply vector categories

I have imported a Vector map into GRASS GIS. There are some problems with the topology and some polygon areas overlap. I used 'v.clean' to break overlapping polygons and now I have multiple polygons ...
2
votes
1answer
373 views

GRASS 7.1 (dev.) i.landsat.toar error

I am working with Landsat 8 image acquired in 2014. I am trying to convert the raw image (DN) to Top Of Atmosphere Reflectance/Radiance (i.landsat.toar) in Grass 7.1 (still under development). The ...
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0answers
39 views

How to determine aerosol model value for i.atcorr in GRASS? (Using Aeronet data)

I am trying to conduct atmospheric correction of landsat 8 image using i.atcorr of Grass GIS. In thıs regard, I need to know Aerosol Optical Depth (AOD) as stated in Grass wiki page. I've found some ...
2
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1answer
42 views

GRASS PyWPS Create a new vector map from user selected polygon

My goal is to select a specific polygon in which the user clicked and make a new vector map that contains only the selected polygon. I see two ways: Convert XY coordinate from literal input to a ...
1
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1answer
101 views

r.cost multiple destinations

I am trying to calculate the optimal route from one archaeological site to multiple sites. I already have the r.cost raster. My question is if I can use r.drain to multiple destination points.
3
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2answers
653 views

Raster map in different zone () than region ()

I am new to QGIS (just installed QGIS 2.0.1) and am having problems running any spatial analysis tools. I followed the instructions on how to call GRASS tools into QGIS, but when I try to run the ...
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2answers
76 views

Addon installation problem on GrassGIS

I am facing a problem with GrassGis 7.0.1. I want to install r.viewshed.cva form Addons. I don't get an error during installation but when I try to open the plugin I get the error : ScriptError ...
0
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1answer
74 views

GRASS problem - r.viewshed.cva addon

I'm a very beginner at GRASS. I'm using GRASS 7.0 and I tried to install r.vieshed.cva extension. When installed, if I type it in the command line, it appears "r.viewshed.cva" is not recognized as ...
7
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1answer
1k views

GRASS v.Overlay/QGIS Intersect Speed intersecting line and polygon [closed]

Im currently trying to convert my scripts from ArcGIS to QGIS but one aspect that is extremely slow (imo) is trying to intersect a polygon with a line feature. I feel as though there must be a better ...
1
vote
1answer
343 views

Joining table data to features in QGIS?

I am trying to make a map using QGIS but I cannot join table data to features in QGIS. In ArcGIS for Desktop you just open the folder and then join the tabular table with the spatial data table. ...
1
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1answer
207 views

QGIS 2.10.1. GRASS Algorithm Processing

While selecting the GRASS algorithms 'Processing algorithm: v.to.points - Create points along input lines' The error message came up: The specified GRASS GIS 7 folder does not contain a valid ...
4
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2answers
1k views

Create isochrones from streets with distance values?

I have made isochrone lines using GRASS and QGIS, as shown. The lines show various distances to fire stations on a street network. Now I would like to turn these lines into polygons that look like ...
5
votes
1answer
892 views

Calculate flow path with QGIS

I am trying to replicate my erosion model in ArcGIS for Desktop in QGIS 2.4. I tried to calculate the upstream distance along the flow path for my agricultural field using QGIS. I did the equivalent ...
3
votes
2answers
861 views

georeference and orthorectification of aerial photos

I am trying to process photos taken with a tetracam ADC micro camera placed on a UAV. I have GPS coordinates and mavlink logs providing roll, pitch and yaw of the UAV. I am having a real hard time ...
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443 views

How can I calculate raster cell area for upslope contributing area

I am new to spatial analysis, and trying to follow this tutorial to generate a topographic wetness index for my area of interest: ...
2
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1answer
99 views

How to brew GRASS with Postgresql support? [closed]

On my Mac, running OS X 10.10.5 and I installed Grass with homebrew: brew tap osgeo/osgeo4mac brew install grass-70 Unfortunately, I cannot choose the pg driver in the db.login menu. Can anyone ...
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0answers
40 views

For preparing watershed delineation with QGIS Grass module I couldn't find r.watershed module

For preparing watershed delineation here some one has described some steps as follows After step 2, I want to get flow accumulation file, but I can not find this kind of module in GRASS, so I pass ...
1
vote
1answer
694 views

Grass 7 on Ubuntu 14.04. Can't start Grass

I attempted to install GRASS GIS 7 on ubuntu 14.04 using these instructions. When I call grass70 from the command line I get a welcome message and a prompt to continue. I then get two error messages: ...
7
votes
2answers
1k views

Moving raster to different mapset GRASS GIS

I have a raster DEM that I created in one mapset but I would like to copy it to another mapset for another purpose. Is this possible within GRASS or can I just copy some files over in the ...
0
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0answers
838 views

Grass Gis 7 does not start in OS X 10.11 El Capitan

Recently I installed the El Capitan upgrade but unfortunately Grass 7 (from the official repository - Grass Gis for Mac) does not start any more. I also re-installed all required frameworks, but I had ...
1
vote
2answers
241 views

How can I extract a smooth river network with QGIS & GRASS?

I´m working with Qgis 2.6.1 and GRASS. I have used the r.watershed module to create a flow accumulation map. With r.mapcalc I have extracted the river network, then i´m using r.thin to thin out to a ...
9
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5answers
2k views

Are there any open source tools to detect and fill sinks on a DEM?

Are there any open source or inexpensive tools to detect and fill sinks on a DEM? ArcGIS Spatial Analyst is just out of my price range.
0
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0answers
57 views

GRASS: launch <wxpython> GUI fails to launch after selecting mapset

I built grass70 from source on Ubuntu 14.04 desktop using the documentation at the Grass Wiki. I can initialize grass70 from the command line, and the startup GUI appears to select my project / ...
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0answers
194 views

Use Anaconda's Python distribution within OSGeo4W

I want to use a Python script that executes Grass commands via os.system(). This of course, has to be executed from a running Grass session. However, when I use the OSGeo4W Grass, it does not find all ...
2
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1answer
179 views

Is possible to merge landsat 8 with High Resolution Satellite Imagery?

i have landsat8 and High Resolution Imagery (1m) in the same study area, is possible to merge them to get one imagery so that i can take advantage of the accuracy satellite imagery.
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1answer
93 views

What are the meaning of Grass drainage direction values from r.watershed

In Grass r.watershed the D8 drainage directions generated from r.watershed are -8. -6.-4.-2, 2, 4, 6, 8 (-1 No Data) What actual directions are these? For example in ArcGIS I know 128 is up and so ...
0
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0answers
36 views

Grass error during script

I've got a serious problem with the following Grass error: r.in.ascii -si input=srsaviLC815173.asc output=srsaviLC815173 --o --q WARNING: closecell: can't move ...
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26 views

Grass GIS table creation error during r.to.vect

When I execute r.to.vect the following error appears: r.to.vect input=sreviLC815109_-120_-120 output=temp feature=area --o --q DBMI-DBF driver error: ERROR: Unable to create table: create table ...
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0answers
26 views

Grass GIS r.to.vect: Prevent neighboring cells with equal values from being unified

I've got different satellite image bands as GRASS rasters, which I want to convert to vector dataset. As I want to compare the IDs of the cell polygons later on, the neighboring cells with ...
2
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0answers
33 views

v.clean batch process withing QGIS 2.10 (PISA)

I get an error message when i try to creat a batch for v.clean operation.. Algorithm v.clean - Toolset for cleaning topology of vector map. starting... local variable 'filename' referenced before ...