Take the 2-minute tour ×
Geographic Information Systems Stack Exchange is a question and answer site for cartographers, geographers and GIS professionals. It's 100% free, no registration required.

I am trying to follow this workflow: [How to generate a DEM from a countour Shapefile?] and it's running fine, and when I hit view output or view results I end up with a flat raster with shading associated with the heights of my contours on screen.

However, I want to see the 3D terrain with hillshading etc, and potentially export a 3d mesh, and from research, think that the nvis module in GRASS can do this for me, but when I try to run this I get the error "module nvis not found"? And QGIS crashes and dies.

When I go to Manage and Install Plugins, Grass is there, and it has let me perform all the other modules I've needed? So not sure what to do with this??

Any ideas or help much appreciated!

Edit: Link to sample data here (.shp+.gml): https://www.dropbox.com/sh/mwxlr3ij78d8gkr/lKwgu3Pafu

share|improve this question
1  
Have you tried working on Grass instead of using the Grass plugin in Q-GIS? I had a similar problem (Grass plugin didn't work properly and Q-GIS crashed) so I performed my analysis in Grass environment. –  dof1985 Nov 21 '13 at 15:41
1  
Lisa is this shapefile publicly available? If you can please share the source data - then GIS-SE can provide some help in creating the DEM with that data (or raise any issues.) –  Mapperz Nov 21 '13 at 16:42
    
Hi @Mapperz - I'm actually using sample data from the OS at the minute in the format I know I will be downloading, as this is a process I know I'm going to have to go through pretty regularly, and so as a GIS newbie I'm just trying to get to grips with it in advance! (I do know the data is also available as ascii grid data which would make my life much easier, but there are reasons I need to begin with the contour based info.) Link to sample .shp and alternative .gml file here: dropbox.com/sh/mwxlr3ij78d8gkr/lKwgu3Pafu –  Lisa SH Nov 21 '13 at 16:54
    
Hi @dof1985 - I've downloaded Grass on it's own, but I'm pretty new to GIS and don't have any script experience so I'm finding Grass pretty tough going! If I need to persevere with that I will though, thanks for your suggestion. –  Lisa SH Nov 21 '13 at 16:56
add comment

1 Answer

You have two solutions:

1) from the GRASS plugin: you are working in GRASS GIS, not in QGIS, so you need to know GRASS GIS

  • you need to first open a LOCATION/MAPSET of GRASS (from the plugin) or create a new LOCATION/MAPSET

enter image description here

  • you will then have access to the GRASS Tools

enter image description here

to:

  • import the shapefile in the MAPSET (v.in.ogr.qgis)
  • transform the shapefile in a raster if you want to use the r. modules (v.to.rast)
  • fix the GRASS region (g.region)
  • use r.contour, r.surf.idw, r.surf.idw2 or v.surf.rst to generate the DEM
  • use nviz to visualise the DEM, change the color, drape a raster layer or add another DEM and/or vector files.

enter image description here enter image description here

2) from GRASS in the Processing Toolbox:

  • you are working in QGIS. In fact, the use of GRASS GIS is transparent, no need to open GRASS GIS, import the shapefile in a LOCATION/MAPSET or fixing a region, everything is done automatically by Processing.

enter image description here

3) What is the difference ?

The Processing version is more limited, you may only view the DEM, with no possibility to drape a raster, add another DEM or vector layers

share|improve this answer
    
Thanks for this, really helpful, though I was attempting to use the grass plugin method, and all works fine until I try to use nviz, where I still get the error message "module nvis not found". Reassuring to know I'm not actually doing anything wrong as such - I will maybe try uninstalling and re-installing! Thanks –  Lisa SH Dec 19 '13 at 16:36
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.