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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Regarding Atmospheric correction and Elevation DEM Projection system

I am trying to conduct atmospheric adjustment of Landsat 8 image bands using 6s algorithm (i. atcorr grass gis tool). It seems, in the input section, an elevation raster map should be provided. In my ...
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2answers
84 views

How to calculate the distance to the nearest water source?

I have a polygon hydro layer of my study area and am trying to calculate the distance to nearest water bodies from my site. Since my site are 2km*2km grids I am not sure how to calculate it? Whether ...
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1answer
34 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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2answers
29 views

Resetting 'cat' column in GRASS?

I've got a regular polygon file that looks like this: Unfortunately, this file stems from a v.overlay so that the 'cat' values are are a bit messed up. I would like them e.g. to start in the upper ...
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1answer
29 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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1answer
35 views

Problems to use v.what.vect in GRASS7

I have problems to use the function v.what.vect and I'm not sure what is the issue. I have a simple forest polygon and try to determine if a point is in the forest or not. # check the output of the ...
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33 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 ...
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25 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 ...
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2answers
152 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
41 views

GRASS GIS i.landsat.toar hangs & holds CPU at 100%

I use python scripting to automate processing of several Landsat 8 scenes. I use a VPS (4 core, 8GB memory, SSD) running Ubuntu 14.04 with GRASS 7.0.1 Line in script for i.landsat.toar: ...
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24 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 ...
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41 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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2answers
90 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
25 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 ...
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0answers
29 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 ...
2
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1answer
90 views

Atmospheric Correction Model Output for Landsat 8 Image?

Following are my procedure, observation and question/ request: Data Source: Earth Explorer Landsat 8 Grass GIS Version: 7.0.2 RC1 Windows 7 32 bit OS I have been trying to conduct an Atmospheric ...
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17 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 ...
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2answers
67 views

Missing v.in.ogr module of GRASS in QGIS Processing toolbox?

I am a new user to QGIS/GRASS and I am having a problem utilizing GRASS. I have several files that I generated in QGIS that I want to import into GRASS so I can use some of the Grass modules. ...
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1answer
55 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.
3
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1answer
111 views

Get ID for each single v.to.points point in GRASS?

How do I get for each v.to.points point an ID in the database (DB). So far I splited the line (each 10m) but it returns only one DB entry for each original line. v.db.select line cat|Id|Name ...
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2answers
77 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 ...
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1answer
52 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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1answer
216 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. ...
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0answers
33 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 ...
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3answers
67 views

Storing large number of mapsets with many raster maps

OS X El Capitan, GRASS GIS 7.0.1 I have a location with about 530 read-only mapsets with each about 2600 raster maps (plus PERMANENT and one link to a read-write mapset), overall 11.255.481 raster ...
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1answer
21 views

Set region with rounded values/coordinates

How do I set a region update with rounded coordinates. I usually set my region from a puffer around my points of interest and round up the north and east coordinates and round down the south and west ...
2
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1answer
29 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 ...
2
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1answer
54 views

Reproducing GRASS GIS network analysis tutorial in QGIS Field Calculator

Im looking to reproduce the assigning of road speeds as denoted in a GRASS GIS tutorial (v.net.alloc tutorial), where the road speed is assigned by road type (i.e. 'interstate' = 75 mph etc.) to then ...
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1answer
75 views

Calculate Volume over sloped ground in GRASS GIS

I am trying to do some volume calculations on a DEM with GRASS GIS. However, I believe r.volume measures everything from 0. The ground underneath the pile I'm measuring is sloped. I would ...
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1answer
78 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.
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2answers
49 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 ...
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1answer
115 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 ...
2
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1answer
58 views

Importing shapefile into GRASS, and multiple new rows appear in attribute table

I am importing a GADM Global Administrative Areas shapefile into GRASS (using QGIS 2.8.2 interface). When I do this, multiple additional rows are created in the attribute table. It goes from this: ...
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0answers
36 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 ...
2
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1answer
77 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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450 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 ...
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1answer
167 views

QGIS 2.10.1 GRASS Processing algorithms not working

I just did a fresh install of QGIS 2.10.1 from the qgis repos (Ubuntu 14.04). I also have grass70 installed (through ubuntugis-unstable). I can see the GRASS7 commands in the processing toolbox ...
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2answers
45 views

i.landsat.toar not working and returning error [duplicate]

First time using grass. I need to convert DN to reflectance. Imagery -> Sat. images tools-> i.landsat.toar. But when I add raster name. I get error. Im using landsat 8 images WARNING: WARNING: ESUN ...
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41 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
116 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
117 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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32 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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0answers
19 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
23 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 ...
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0answers
30 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 ...
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1answer
57 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 ...
2
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1answer
28 views

Panchromatic Image Classification GRASS GIS

How to perform an unsupervised classification of a single panchromatic satellite imagery in GRASS GIS? I tried it many times but I keep being prompted for a second image or other images in the ...
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1answer
51 views

v.kriging Addon not installed - GRASS GIS 7

I am using GRASS GIS 7. When I try to install "v.kriging" module using "g.extension" command, it is not installed. Though it says that the extension is successfully installed, I get the error ...
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1answer
44 views

can grass gis module be used in parallel mode

i want to use my customized grass gis(6.4.3) module for separate bands of a sensor in a parallel mode. is it possible? i have created separate location and if one band is executed ,for the second band ...
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25 views

Is there a lower bound on the std deviation for v.kernel in GRASS?

I'm using the v.kernel function in GRASS to create heat maps. I am able to generate an acceptable heat map using a std deviation of .2 and a several thousand rows and columns. After the map is ...