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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3d model to point cloud

Excepting FME, is there a way to convert 3d model to point cloud?
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34 views

develop rooftop solar radiation potential from 3d buildings model (3dm)

Need to create solar cadastre without having LIDAR data. Have 3d buildings model in .3dm (150 000+ roof surfaces, 500 000+ facade surfaces unmapped, dtm 15x15m) with a lot of multipatch geometry ...
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1answer
37 views

View feature space for multi-band files

I am trying to plot a feature space (scatter plot) for some SPOT images in QGIS 2.8.1. I know a histogram is available in the file properties, but I want to plot eg. Band 1 vs Band 2 to see the ...
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2answers
67 views

Loading Grass 7.0 vectors in QGIS broken?

Running QGis 2.8.1 in Win7 (64bits), installed through OSGEO4W. When trying to load a Grass 7.0 vector file in QGis, the program will simply crash without any notice. I can load old Grass vectors ...
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4answers
1k 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.
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2answers
64 views

Difference between FCELL, DCELL and CELL in GRASS GIS?

Can anyone clarify for me please the options in the "precision" parameter when calculating slope, aspect and curvature in GRASS GIS. What is the difference between FCELL, DCELL and CELL?
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1answer
74 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': ...
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0answers
58 views

QGIS-GRASS firespread simulation module [closed]

I'm trying to do some fire spread simulations in QGIS with GRASS fire spreading simulation module. QGIS ('Processing Toolbox' > 'Geoalgorithms' > 'Misc' > 'Fire spreading simulation') GUI. Already ...
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1answer
69 views

Removing salt and pepper effect

In a land cover raster (categorical map) that is a product of classified satellite image, what is the best way to remove "salt and pepper" effect from the image after classification. I am not ...
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42 views

QGIS, GRASS and WINDOWS 8

Good morning, I'm using QGIS 2.8.1 (Wien) on Windows 8 x64 bit. When I'm trying to lunch the GRASS plugin (6.4.3), Windows shows me the error g.mapset.exe has stop working, then after some times, ...
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1answer
152 views

Empty raster returned after GRASS i.atcorr with Landsat8 data

I've searched at length on previous forums but no solution seems to work for me. I'm trying to run the i.atcorr module on GRASS (version 6.4.3 on a Macbook Pro, Mavericks OSX) with Landsat8 imagery. ...
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18 views

Using r.neighbors on borders

I have a raster file with pixel size 30 x 30. At the upper border there is half row with "no data" pixels. I want to use the mode function to replace them. I have only thought r.neighbors (from grass) ...
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31 views

Pansharping Problems with Landsat8

I downloaded Landsat 8 Data from Earthexplorer and used that Workflow: http://courses.neteler.org/processing-landsat8-data-in-grass-gis-7/ Now I want to pansharp the Landsat 8 Datas. For that I used ...
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0answers
25 views

Is it right to remove salt & pepper effect from a product produced by clean images?

I have two images from classification (different years) and I want to find the changes of land cover . I have cleaned the two images (salt and pepper). When I create a cross product of the category ...
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0answers
16 views

GRASS_INFO_ERROR(16605,1) while running a GRASS tool

I have a fresh install of QGIS 2.8.1 with the GRASS plugin on Ubuntu 14.04. I opened the mapset I've created in QGIS 2.6.1 on Windows 7. Then I tried to run v.in.ascii Grass tool and I got following ...
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1answer
87 views

How to visualize a point cloud in 3D with GRASS?

I'm new with qgis and grass so I'm sorry if there is a straightforward answer for this question but I can't seem to get it done. I've imported a pointcloud into qgis from a datafile. Now i'd like to ...
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1answer
41 views

G_realloc: unable to allocate 46320000 bytes of memory while managing large .xyz through v.in.ascii

I tried to convert large (~180MB) .xyz file into vector through v.in.ascii in QGIS Brighton (2.6.0) Grass plugin (it should be Grass version 6.4.3). The "primitive registration" stage lasted very long ...
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3answers
2k views

How to rasterize a vector map?

I am looking for a way to create a raster grid from a vector map. I have a map consisting of shapefiles which I want to export as a raster with UTM coordinates. I was thinking of something using the ...
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2answers
113 views

How calculate pixel by pixel the mode (statistic) of multiple rasters (geotiff)?

I have 12 land cover maps, and I would like to calculate the mode to each pixel of the 12 maps (they have the same resolution and dimension). I mean, the final map would be the mode for each pixel of ...
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2answers
145 views

QGIS – Raster Calculator: Using flat (no data) areas of an aspect-raster in the raster calculator

I´m playing around with the Raster tools, following more or less the qgis-tutorial but using my own data. When I calculate the aspect of a DEM, flat areas are (logically) left without data. However, ...
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6answers
25k views

How to build effective heat-maps?

Using ArcGIS, QuantumGIS, Grass, and/or GVSIG What are some of the tools and processes involved in building effective heat maps? What are the plugins involved? What are the major data requirements? ...
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34 views

Splitting lines at a specified distance and add attribute

I have used QChainage to create points along a line every meter. What I am ultimately looking for, is to split the line layer along this point into segments with the chainage distance as an attribute. ...
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1answer
45 views

Trouble importing NumPy in GRASS. Architecture

I can't get GRASS to work on my system, and after doing some digging I think it is related to me using 64-bit python. I'm not really sure. I get this message... This module requires the ...
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2answers
38 views

Shell/GRASS: Exit loop upon raster value

I am running a loop from a shell script in GRASS GIS 7. Basically, values are subtracted from a raster in each step. I want the script to stop/exit if any of the raster values is 0 or less. Is there a ...
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45 views

Execute Spyder within Grass GIS

I'm using GRASS Gis with a small Python script. Is there a way (for windows users) to use the sypder ide within grass? I looked at http://grasswiki.osgeo.org/wiki/Tools_for_Python_programming but ...
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1answer
35 views

GRASS Gis v 6.4.4. KeyError: 'version' when start

When I try to start the GRASS it gives me the following error GRASS 6.4.4 (Hellas):~ > ERROR: MAPSET Hellas - permission denied Traceback (most recent call last): File ...
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1answer
27 views

GRASS 7.0.0beta3 / statistics change after TIF import?

I'm new to this forum, and pretty much a beginner with GRASS (7.0.0beta3 installed atm). So my question is the following: Statistics (mean, min, max) change quite a lot after importing a .TIF grid ...
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0answers
46 views

setting null values to 0 Landsat 8 Grass 7.1

I am working with Landsat8 images and need to run the albedo function in Grass 7.1.svn. In order to do this, I need to set the null values to 0 to eliminate the black border around the images. This ...
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1answer
31 views

Error in executing commands in GRASS GIS

I'm using Grass 6.4.3RC2. I have a problem because when I execute the command: r.radcov csv_file=cell_list_hataDEM_umts_amc_testTEST.csv dem_map-AlbSRTMdem@PERMANENT clutter_map=AlbClut@PERMANENT ...
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1answer
26 views

How to import and layer stack seperate ndvi bands to grass gis?

I have 20 separate single band NDVI files. I have to import this into GRASS and stack them into a single 20 band image. How can I do that?
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50 views

Hydropower Calculation

I have assigned the elevation and the volume flow to each point at a river (with v.to.db and v.what.rast). Now I want to calculate the Elevation difference between each pair of points and then ...
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26 views

How to load “soil types” in QGis?

I want to show soil transmissivity per pixel. Thus, I determine water holding capacity of each pixel (ignored other effective parameters). Respectively, I wonder, What is the soil data format and How ...
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1answer
68 views

r.composite gives blank image output in GRASS GIS

While running r.composite in GRASSGIS GUI command the image formed looks absolutely blank. The data I used is listed here below. IRS-LISS III Multispectral coverages. (i.e. band 2, 3 and 4 for Blue, ...
4
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2answers
201 views

95 percent volume contour

I generated, from point data, a kernel density map using GRASS, and I would like to identify the 95% volume contour in it. Is it possible in GRASS? Thank you
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136 views

Assessing Flood Hazard Risk Zones using DEM

My Question: What is the best effective way to quickly estimate flood hazard risk areas using DEM data? Ideally I am looking for guidance to move forward and perform this process over large areas ...
4
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1answer
112 views

How to calculate “water accumulated in each cell” using QGis?

I create channel network and catchment area from a DEM with SAGA GIS. I know that flow is starting from a cell to an other cell. Firstly, a cell is filled with water and then it is starting to flow ...
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0answers
32 views

Horton Stream Order as Category for r.fixed.segmetpoints with GRASS?

I'm working with Grass GIS. I want to use v.segment to set discrete, equidistant Streampoints (starting from each mouth). Since the water network is too large, it is impossible to define the rules ...
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0answers
40 views

How to decide when flood started depending on the rainfall data?

I created a raster with the point values (mm) of rainfall data by interpolation in the raster menu. So I have a raster rainfall data and a DEM. With this rainfall data and a DEM corresponding to ...
2
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2answers
28 views

Harvesting pixels using GRASS GIS

having a binary raster map of pixels of interest, a road network, and a target point, my goal is to get a raster map with network pixels having as value the number of pixels of interest they allow to ...
0
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1answer
84 views

Isochrone driving/public transport map : Grass or postgis?

I have to do Isochrone driving / public transport map. It would seem that the two better open-source solutions are grass and postgis. Could you tell me which one is the better? the easier to ...
1
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1answer
47 views

Calculate River Runoff Volume (Q) with GRASS

I want to calculate Hydropower between points at a River. I already created a Rivernetwork and the Accumulationmap (without weighting) with r.watershed. My next Step was to set equivalent points along ...
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1answer
61 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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1answer
39 views

tutorial for deriving solar insolation estimates from high resolution Digital surface model

I want to estimate solar insolation using grass gis. I have a high resolution DSM generated from Large Format Digital camera.Being a novice in this field i Would like to have a tutorial and steps to ...
0
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1answer
32 views

How can I fill the category field in a raster using GRASS

I have a tiff file with land use data. The land use class in in the value field, but the label field is empty. Now I want to find out which is the area covered by each land use class, but GRASS does ...
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20 views

automatic extraction of dtm using grass gis

i have generated dsm using erdas lps tool which is in img format. i want to import this file in grass gis and extract dtm. can you please tell me how to input the data , in which format it should be, ...
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23 views

What is the background processing of rainfall thresholding?

I want to create a flood map using Quantum GIS. First of all I create catchment area (flow accumulation). Then, I delineate a Channel Network by applying a threshold to flow accumulation. So I want to ...
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16 views

How to visualize insolation rasters over color orthophoto in grass

I have generated insolation time raster map using DSM, slope, aspect for day 100 and time 10.95 hrs using r.sun module in grass. The output insolation raster map (color table) i want to overlay on ...
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4answers
504 views

Determining gradient of road segment

I've a shapefile of roads data. It contains information about terrain of road segments, i.e., hilly, flat, undulating, etc. I want to determine gradient of every road segment. I know this might ...
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1answer
41 views

How to change the Map Units in Grass?

because v.segment measures all offsets in map units, i have to change it. (I want to put all of 50 meters a point) So I checked g.proj -p: -PROJ_UNITS------------------------------------------------ ...
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0answers
29 views

problem with running raster calculator in grassgis

When I was trying to do NDVI with grassGIS I faced a problem. I cannot run the raster calculation. When I looked to the command console I see that (Sat Feb 21 12:41:58 2015) r.mapcalc ddes = ( ...