Tagged Questions

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
142 views

How to fix QGIS crashes when using GRASS toolbox?

I've installed QGIS 2.0.1 on Ubuntu 12.04. exactly as explained on qgis.org . Unfortunately QGIS crashes when trying to use any GRASS model (r.aspect as example): just opening QGIS, click on toolbox ...
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142 views

How to install GRASS in QGIS Dufour?

How do I install GRASS to run in QGIS 2.0.1? GRASS is not listed in the Plugin Manager and attempting to access it via the Processing Toolbox gives me the following error:
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0answers
120 views

Merging contour lines along tile boundaries

I am working with the CANVEC data set. The data in canvec is broken up in to mapsheets. eg. 116B04. I have data covering the entire province of the Yukon. I have merged all the data in to one ...
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34 views

Raster Interpolation of Different DEMs in GRASS

I am trying to generate a DEM for surface runoff modeling in GRASS. I have a DEM for the entire watershed at 1ft resolution and another for the small area within that watershed (a parking lot) I am ...
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131 views

Trouble with opening/using i.atcorr in GRASS

I'm relatively new to GRASS. I'm running version 6.4.3 on a Windows 7 machine. I'm trying to process Landsat 5 imagery from multiple states, so I was hoping to approximately follow the workflow here: ...
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1answer
263 views

How to pansharpen radiance/reflectance Landsat 8 in GRASS 7?

first at all, I have to say that I'm new GRASS user. I would like to make a pansharp in GRASS 7 with reflectance Landsat 8 bands. I have revised some related posts and blogs, and I didn't find out if ...
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0answers
110 views

GRASS i.atcorr outputs unusual values

I have problems using the atmospheric correction module i.atcorr in GRASS 6.4.3RC3. I try to correct two Landsat ETM+ scenes, but the output for bands 4 and 7 has values that seem to be incorrect. ...
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130 views

Grass installation - MSVCR71.dll error while .Net installed

I have .Net 4.5.1 installed and resently installed GRASS 6.4.3. When I try to start the software I get the MSVCR71.dll error. The only solution suggested in the guide is to install the .Net ...
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1answer
199 views

How to define correctly the Grass region in Qgis

I know that my question could be pretty basic for some of you. I am trying to learn GRASS. I have some raster layers and a vector file in EPSG 32614. Using the grass plugin I defined a new map set, ...
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1answer
166 views

How to join USDA SSURGO soil table data to features in QGIS?

I am trying to make a soil map using QGIS. The only problem is that I cannot join table data to features in QGIS. In ArcGIS for Desktop you just open the folder and then join the tabular table ...
9
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1answer
576 views

Import GRASS and SAGA modules to python script

I'm new at this. I am "building" a python plugin for qgis and I want to import modules from GRASS and SAGA but I don't understand how to do it. The plugin I want to import is Kriging interpolation ...
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1answer
118 views

Set Grass Region in Python grass.script

How can I set the Grass Region in Python without already having a map in the Mapset? Basically I am looking for the equivalent to this window Currently I am only able to extent an existing region, ...
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60 views

Error north coordinate not allowed using r.water.outlet in GRASS

When I am trying to delineate a basin from this code: r.water.outlet drainage=drainage1 basin=basin1 \ east=518675.070417019 north=911542.292643082 Coordinate system: UTM-cartesian xy (used by ...
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1answer
120 views

How to get the direction raster from r.walk or r.cost

I am trying to use r.cost and r.walk and r.drain to calculate the shortest path from an archaeological site to the nearest basalt source. I am using all this algorithms with the processing toolbox (I ...
5
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1answer
204 views

What are the advantages and disadvantages importing vs linking data in GRASS?

I'm fairly new to GRASS, and only recently discovered the r.external and v.external functions. I'm used to working with R and QGIS where all the data is "external". Typically I keep vector data in ...
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1answer
54 views

Re-sizing Raster file pixels

I have 2 JP2 aerial imagery files that are incorrectly sized. They are 100x larger than the other aerial images but correctly geo-referenced (starting x, y co-ordinates). I believe the issue is their ...
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0answers
107 views

Touch up tool for rasters?

I was wondering if it were at all possible to manipulate/massage rasters (eg Geotiff) using Qgis plugins or Grass?? By manipulate, I mean manually smooth off interpolation artefacts, blended surface ...
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2answers
673 views

install GRASS Addon in with QGIS

Win 7 QGIS 2.0 GRASS 6.4.3 Hi everybody, I want to install some GRASS-Addons to use them in QGIS. Therefore I run GRASS-Plugin in QGIS an open the GRASS-Shell type: g.extension GRASS opens then i ...
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3answers
198 views

SRTM NASA hillshade grainy appearance

I'm trying to create a hillshade surface from SRTM files downloaded form Earth Explorer, but the appearance is not the expected. It has a grainy surface that I would like eliminate to have a ...
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2answers
132 views

Grass GIS 6.4.3, How to create a .PTS file

I'm trying to export a raster map in order to use it in the Flo-2d program. This program needs a .pts DTM file, do you know how I can create it? Alternatively, I can use a XYZ file looking like this ...
2
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1answer
661 views

How to get custom colormap onto 3D NVIZ in QGIS GRASS

I am trying to create a 3D version of my 2D raster using QGIS GRASS NVIZ. I have been following these steps: ...
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1answer
102 views

QGIS Grass Plugin fails with r.cost.vect

I tried the following in QGIS with the Grass Plugin: r.cost input=preCostSurface@albi start_points=OSMroads@albi output=cost0109 max_cost=0 And I get the following error: Dev note: Adapted sites ...
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1answer
481 views

Map Algebra - Grass GIS (r.mapcalc) merge two raster with NoData value

I have a slope raster and a road raster. The black pixels in the road raster are NoData values and the pink pixels have a value of 1. They don't cover exactly the same area. I want to create a new ...
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2answers
424 views

How to remove z & m coordinates from shapes with QGIS? (Or arcgis, grass, gdal, Python…)

I've recently received some parcel data in shapefile format that has z & m coordinates (all = 0.0). The WKT for a typical parcel looks like this: "MULTIPOLYGON (((2672464.560700002 ...
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0answers
207 views

how to make decent sense from scattered river depth measurements

I sampled river depth at scattered positions and I want to be able to make a map and GIS layers out of it. My problems are: As the river meanders the interpolation I do in scientific packages i,e. ...
2
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0answers
182 views

How can I create random concave polygons for test purposes?

In the context of generating random test data using QGIS (in a shapefile): I can generate random, continuous (adjacent) polygons by first creating n random points using ftools and then generating a ...
5
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2answers
142 views

filling up a depression to create new surface

A collegue here has a problem I cannot help with. She has the surface (as raster) of a landslide release area (from AFTER the slide) and wants to calculate the calculate the theoretical/approximate ...
0
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1answer
200 views

How to perform GRASS v.rast.stats via QGIS

I have been using qgis for the last few months. I got interested in using GRASS tools through QGIS. I wanted to compute zonal statistics for a raster surface for a given polygon layer. I loaded the ...
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1answer
137 views

Removing Image Stripes / Scan Line errors

I have some seabed bathymetry data derived from seismic reflection profiles in a 2.5D dataset (closely spaced lines). The data was gridded by another worker in SMT Kingdom suite; I'm not familiar ...
1
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2answers
121 views

Getting started with 'shell scripting loops' in GRASS

I'd like to work through the MODIS-Aqua example here. But typically the hardest bit is getting off the ground. What specifically does it mean by 'shell scripting'? is it referring to the command ...
1
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1answer
149 views

How to compare accuracy of two DEM using GRASS

How do I compare accuracy of two DEM data (lidar and srtm) (possibly through rmse) using GRASS GIS? thanks
2
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3answers
1k views

Viewshed / Line of Sight analysis- as a batch process?

I wish to carry out a line of site analysis similar to the subject in here (preferably within QGIS): Visual Impact Assessment in QGIS or GRASS Scenario: I have two points, A and B. Point A is a ...
1
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1answer
54 views

Communicate synchronously & continuously (coords, etc) from terminal to application-based mapping software such that updates are displayed live on map

I run a lot of spatial queries. Hundreds of thousands a week. While these things are running, it would be nice if I could see what (where, actually) my scripts are working with. Distance calculations, ...
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0answers
51 views

Delete polygon underlap?

I am editing a layer in QGIS with severe polygon overlaps. Is there a way to delete the underlapping portions (i.e. the invisible parts) using QGIS? If I import the layer into GRASS using the ...
3
votes
1answer
587 views

Is there a Focal Statistics (spatial analyst) tool in ArcGIS equivalent in QGIS?

I'm attempting to use QGIS v2.0.1 to accomplish the same tasks that I can do using ArcMap v10.1 and I'm running into some trouble finding equivalent tools. In ArcMap I am using the Focal Statistics ...
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0answers
23 views

Unicode Characters in GRASS ps.map instructions file

I am trying to put text on a ps.map generated map and the text contains the degrees symbol. I can insert the symbol into the instructions file, and it looks fine, but when I generate the map, the ...
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0answers
23 views

accuracy of classification in qgis [duplicate]

I have my classified map and my validation points. I performed point sampling with validation points to my classified map. but i am fuzzy with my next step. Some help?
4
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1answer
205 views

GRASS 6.5 or 7.0 - Need Help with Loop Script

I am new to Python and scripting in general. This is also my first time a posting question. My overall goal is to create a script that I can cycle through all the raster maps in a mapset and then ...
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0answers
154 views

Problems with SEXTANTE

maybe the answer is somewhere, but i can't find it right now... I'm getting problems with SEXTANTE and algorithms with GRASS, SAGA... Always is the same, they can't open the files, the error is the ...
1
vote
1answer
152 views

Grass GIS and Python Error

I am trying to use Python with Grass GIS. To get started I try to read in a raster TIFF. The import of grass.script works fine: import grass.script as g But if I am trying to run a command I get ...
1
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2answers
317 views

How to find the shortest route between two points based on cost surface?

I have two locations: (A) starting point and (B) designation. Also I have a slope raster. I want to find the cheapest path between these two locations based on the slope (it is more expensive to ...
4
votes
1answer
365 views

Is it possible to use GRASS GIS in Python stand alone scripts?

I am trying to find a least cost path script for Python. I came across r.drain from GRASS GIS. Is it possible to use GRASS GIS in a Python stand alone script? If so where can I download the bindings?
0
votes
1answer
471 views

GRASS in QGIS not working (windows XP)

I am unable to use GRASS algorithms in QGIS 2.0.1 (on windows xp). I've already configured the GRASS path. The algorithms seems to work correctly (I cannot see errors in the log), however in the end ...
0
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1answer
93 views

How do I install mdenoise?

How do I install mdenoise in GRASS 6.4.3? I've already successfully installed r.denoise, and have downloaded mdenoise from wget http://www.cs.cf.ac.uk/meshfiltering/index_files/Doc/mdsource.zip. How ...
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0answers
216 views

Atmospheric correction for RapideEye without atmospheric parameters

I'd like to perform an atmospheric correction of my RapidEye images but metadata do no include atmospheric parameters required to use the 6s algo implemented in the Orfeo ToolBox. Is there a solution ...
1
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1answer
104 views

How to set opacity for GRASS layers using command line?

In the process of learning GRASS, I am finding that I can learn many of the command-line methods that I need for scripting tasks from using the wxGUI, as it conveniently shows most of the underlying ...
0
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1answer
67 views

How to set partial transparency for GRASS layer?

I am trying to style layers in a GRASS monitor such that they are partially transparent. I'm guessing that there's a module for that (d.shadedmap seems close), but I haven't found it. I need a ...
2
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0answers
207 views

How to Install GRASS Addons to use in QGIS

WIN 7 QGIS 1.8.0 GRASS 6.3.4 I want to use r.viewshed in QGIS. therefore i want to install it in GRASS by using the GRASS interface. Followin Error appears. g.extension.py extension=r.viewshed ...
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0answers
117 views

where to perform principal components analysis and tasseled cap transformation

I want to perform a principal components analysis (pca) and a tasseled cap transformation (tasscap) for a classification.Should i perform pca and tasscap on the original bands of my image or on the ...
1
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1answer
120 views

How to duplicate this QGIS workflow with gdal/GRASS? (reproject and crop a raster)?

I have a number of rasters (rgb images) that I want to re-project and crop. I have established a workflow for doing this in QGIS, but I'd like to do it using gdal modules, because the output is being ...