Tagged Questions
1
vote
1answer
74 views
QGIS contour lines shapefile to DEM help
I want to create a DEM from depth contours (shapefile) in QGIS. I've been trying to work out how to do this based on this previous question, notably from this link from that page, however I'm stuck, ...
1
vote
0answers
24 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
40 views
saga & grass configuration in sextante (ubuntu)
I have some trouble in running saga and grass algorithms in sextante. When I double click it appears a pop-up saying:
Missing dependency.This algorithm cannot be run :-(
This algorithm requires SAGA ...
11
votes
2answers
261 views
What's the relation between QGIS and GRASS?
I have been working with GIS and remote sensing in an university and professional environment some ten years ago (ArcInfo etc), so I have some experience even though somewhat outdated
Right now I am ...
2
votes
3answers
105 views
How to clean layers from non topological databases?
I'm doing my internship in a consulting office which is switching from MapInfo to QGIS/GRASS 1.8.0.
I posted here a few days ago about the way to clean a polyline from a Lidar data with v.clean.
...
0
votes
2answers
91 views
How to resolve missing Python module (importlib) for GRASS/Sextante?
I have installed the nightly build of QGIS 1.9 from Larry's Dakota Cartography site, and have downloaded the latest Frameworks from William's Kyng Chaos site.
However, I am unable to install the ...
4
votes
1answer
117 views
How to repair and clean contours from high data resolution (lidar)?
I'm unsuccessfully trying to make a bathymetric map with contours extracted from Lidar data at 1 m resolution.
The extracted contours have a lot of artifacts like dangles and islands.
First I used ...
7
votes
3answers
200 views
Howto setup and use a remote GIS workstation (QGIS,GRASS,PostGIS)?
I'm using QGIS (and sometimes GRASS and PostGIS) on my 2009 MacBookPro for my thesis project.
I was wondering (during an endless batch generalizing in QGIS) if I can set up a server so I can work from ...
2
votes
1answer
95 views
How to reclassify a float raster?
I have three rasters which represent distance (in metres) from certain things (bus stops, parks, libraries). I would like to reclassify these rasters so that they get integer values based on the ...
0
votes
1answer
30 views
Full Easting and Northing coordinates values cannot be encoded in GRASS r.water.outlet in SEXTANTE-QGIS
The Easting or Northing coordinate parameter accepts only 5 digits. The Easting and Northing values for my outlet are 6 and 7 digits long (integer). How can they be encoded in r.water.outlet? Can ...
0
votes
1answer
82 views
Sextante grass folder incorrect?
What is the correct grass folder in Sextante? I alway get this message:
The specified GRASS folder does not contain a valid set of GRASS
modules. Please, go to the SEXTANTE settings dialog, and ...
0
votes
0answers
75 views
qgis plugin: “WindowsError: [Error 6] The handle is invalid”
OS: Windows 7 64bit
GIS: QGIS 1.8 (qgis.org/downloads/QGIS-OSGeo4W-1.8.0-2-Setup.exe)
path variable:
GISBASE=C:\Program Files (x86)\Quantum GIS Lisboa\apps\grass\grass-6.4.3RC2
...
3
votes
1answer
95 views
How to split line at a specified distance and getting coordinates of start and end points of each line segment？
I tried v.split in GRASS：
and my notebook ran a lot of time but showed this error：bad allocation, then I click "OK", and got nothing.
Are there other ways to split lines？and I hope to get 2 new ...
0
votes
1answer
76 views
import grass.script as grass under windows 7
OS: Windows 7 64bit
GIS: QGIS 1.8 (qgis.org/downloads/QGIS-OSGeo4W-1.8.0-2-Setup.exe)
I have created a plugin for QGIS, with the QGIS plugin builder.
Now i would like to import grass.script into ...
1
vote
0answers
58 views
GRASS Plugin to QGIS error
I am installing QGIS and GRASS as part of an FOSS GIS class I'll be teaching this summer. I used the OsGeo4W installer. This installer has always worked flawlessly for me except on the machines at the ...
2
votes
0answers
83 views
Flow modeling and FOSS GIS; lahars and HEC-RAS
What are the options for FOSS flow modeling of dilute debris flows in QGIS or GRASS?
Have you, or can you refer me to studies where the authors, tested these models/plugins/functions/etc. for use in ...
3
votes
1answer
77 views
Autocorrelated DEM with QGIS or Grass
I was wondering if there is a way to make an Autocorrelated DEM within QGIS or Grass. I am looking to do this with stereo aerial photography. I am able to do this with a number of COTS tools, but I ...
2
votes
0answers
53 views
How to join nodes to network lines ( and not the other points)
I'm trying to do a shortest path analysis on my network. In order to prepare the network and attach polygon centroids to the roads, I used GRASS' V.NET operation=connect. the problem with this ...
0
votes
3answers
143 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 ...
3
votes
1answer
203 views
How do I find vector line bearing in QGIS or GRASS?
How can one extract the bearings from a set of lines in a vector file?
I'm trying to find the bearings of several straight vector line segments (simplified contour lines, actually) and can't figure ...
0
votes
0answers
88 views
Help in GRASS/QGIS/Python
I have Idea about ArcGIS, and a bit of QGIS and zero programming knowledge, which I am trying for thesedays. I saw GRASS GIS and have started working with shapefiles, which are not being loaded... :( ...
1
vote
1answer
82 views
How to invert polygons (or other options for exterior styling)?
I have a shapefile containing many polygons that I want to use to mask a raster. I have tried gdalwarp -cutline <shapefile> -crop_to_cutline -srcnodata -9999 -dstnodata -9999 ...
0
votes
0answers
42 views
Add GRASS Addon to Sextant within QGIS
I have successfully installed r.viewshed as an add-on in GRASSS 6.4.2. I would like the command to show up in the list of algorithms within Sextante. Is there a way to make Sextante "aware" of ...
0
votes
0answers
48 views
Why don't libgrass.so.1.8.0 and libqgissqlantconnection.so.1.8.0 load?
I have compiled Qgis 1.8 at Ubuntu 12.10, but some phyton plugins does'nt work, like sextante.
Trying to solve this problem, some files don't have been load. They are: libgrass.so.1.8.0 and ...
2
votes
1answer
48 views
Is it possible to use a WHERE clause with Grass v.in.ogr for DGN sources?
I am trying to import a .DGN with Grass v.in.ogr in QGIS. I am able to import the DGN perfectly, but I would like to filter the elements using the WHERE option. From searching, reading and testing I ...
1
vote
1answer
96 views
Grass v.clean.snap with Polygons
I am doing some topology testing using Grass in QGIS. I am hoping to snap nodes to eliminate gaps between polygons. When I use the v.clean.snap function in Grass it does not work on polygons. When I ...
2
votes
0answers
116 views
Topology problems with QGIS/GRASS
*edited file links below
I'm working on several NGO projects at the moment, all of which are reliant on being able to use a district level map with some 490+ features, and I am running into some ...
0
votes
2answers
46 views
How to align directions of connected lines?
I have a vector line made of different pieces of lines with different directions. I merged the lines to one. But this merged line still have different direction in its "invisible" parts. I want to ...
0
votes
0answers
72 views
Free and Open Source GIS Desktop Dissertation Survey – Participants wanted [closed]
I am currently in my last year of MSc Information Technology course at the University of the West of England. I am required to undertake a dissertation project. I am conducting a study on the level of ...
1
vote
1answer
152 views
Rasterize vector with gdal
"I would like to calculate the Euclidian distance from a residence to a public service of interest e.g. the distance from a residence to a green space (as the crow flies) in QGIS. After browsing the ...
2
votes
0answers
87 views
Export to shapefile qgis
I am trying to develop hotspot map showing point density in our gis based web application. After searching for an option I have decided to use v.kernel command. I have a table containing some point ...
1
vote
3answers
57 views
How do I active “Open GRASS tools”-button?
I have opened to GRASS layers and need to use the "Open GRASS tools"-button. This button remains unactivated somehow. Whilst the "Edit GRASS vector layer" right next to it works perfectly fine. What ...
1
vote
1answer
132 views
How do I use the GRASS command line tools within QGIS?
How do I use the GRASS command line tools within QGIS?
I use the QRASS plugin to open the mapset, and then I open the GRASS tools window. I click on 'GRASS shell' under modules and it brings up a ...
2
votes
1answer
36 views
What defines a Class in the Heat map plugin?
What defines a Class in the Heat map plugin? As in:
"Black holes like that are usually caused by raster values exceeding the range of the color ramp. Try adding another class with a higher associated ...
1
vote
0answers
83 views
Heat Map trouble: Is this a data formating problem?
I'm playing with the heat map plugin with QGIS. I've run through QGIS tutorial:
http://docs.qgis.org/html/en/docs/user_manual/plugins/plugins_heatmap.html,
using the airports data set as explained ...
3
votes
1answer
100 views
Hydro-Enforced/surface constraint DEM Creation using GRASS/QGIS
I am wondering if there is a way to create a hydro-breakline enforced DEM by means of any open source solution?
I am able to create a DEM from Lidar data using GRASS, but would like to enforce some ...
0
votes
1answer
106 views
How do you use 'reclass' in GRASS?
It could be user error, but for some reason, the reclass tool is just hanging and hanging...
QGIS 1.8
Compiled against GDAL/OGR 1.9.2
Ubuntu 12.04.1
Running the tool from the Sextante toolbox
Input ...
3
votes
1answer
111 views
How to prepare road network for routing in QGIS or GRASS
I have been working on a road network and I want to run shortest path algorithms on it. One problem is that some lines come very close to each other, but are not connected.
Is there a way to connect ...
4
votes
1answer
134 views
How can I avoid reprojection gaps when merging DEM rasters?
I have two raster DEMs in same resolution I want to bring together. I was using the merge-function in SAGA, GRASS and QGIS but I always get the following result:
What do I need? Where could the ...
1
vote
1answer
82 views
How to remove terracing from Civil3D GeoTIFF export?
I've received a GeoTIFF DEM that was exported from Civil3D and at every contour there is a distinct terrace created when I process an aspect or slope in QGIS with the GRASS plugins.
I've looked ...
1
vote
0answers
81 views
How to handle/ avoid intersect errors when clipping the difference between two layers?
Using QGIS + Grass, I've added a shapefile of coastline and islands to my map.
I then buffer this shapefile to create a coastal zone of a known width. At this stage the buffer consists of the ...
0
votes
0answers
209 views
How to resample a raster in QGIS?
I've got a boundary file that I would like to resample the raster file from a 30m grid to a 10m grid inside the boundary file. When I try and do it in Qgis or Grass all I get is one big raster cube ...
4
votes
4answers
192 views
How to Find Dead-ends in a Road Network
I'm trying to remove all the dead-end roads in a road dataset (lines) that are less than 100m long.
How do I identify roads that are dead-ends (no exit)? The 100m part is easy. I know how to use Arc ...
6
votes
1answer
271 views
How to enable GRASS-modules in QGIS?
I have the latest QuantumGIS-1.9.0-master from Github with python-modules support and full GRASS-integration (GRASS-4.6.3-RC2) on Linux.
When opening the GRASS-tools plugin, it only displays six ...
7
votes
2answers
597 views
How to correctly install QGIS with plugins and GRASS-integration from source?
I'm running a Sabayon GNU/Linux (based on Gentoo) at my home desktop system and I want to install Quantum-GIS.
I'm currently using the qgis-1.7.0-package from the repositories. But this is somehow ...
0
votes
1answer
98 views
How do I repair NVIZ error: 'Can't find a usable init.tcl'?
How do I repair the following problem:
The error occurred while I was trying to run NVIZ in the GRASS environment in QGIS. NVIZ however runs perfectly in GRASS. On checking the directories ...
2
votes
1answer
85 views
Error when importing vector layer into GRASS
I am trying to import a vector layer into GRASS, but I keep receiving the same error. The values in the vector layer are important because I would like to use them to create a heatmap. What could I ...
5
votes
1answer
183 views
How to create a heatmap using values?
How do I create a 'heatmap' in QGIS based on the values of the different points? I did do this once before with rainfall, but can't remember how!
5
votes
5answers
452 views
How to calculate distances in a point sequence?
I'm looking for help calculating the distance between a sequence of points that are in a single Shapefile in QGIS. Below is what my data look like and a blank distance column I've added to show how ...
3
votes
1answer
497 views
Importing shapefile in grass
I have very simple shapefile, which consists of couple of polygons, and I wanted to snap boundaries automatically. Unfortunately qgis doesn't have such function, but grass has according this answer: ...
