[GRASS-user] DTM/DEM to TIN
As far as I can see GRASS doesn't provide any ready-to-go tool to generate TINs from grid digital elevation models. I know I can transform a grid to a regular mesh somehow (probably using the Triangle lib for the last step) but I can't find tools to generate TINs, given a certain amount of tolerance, which preserve significative locations (like those obtained by TPI for example) and shapes (in a morphonetric sense). Does anybody has experience on this? The general aim is generating terrain meshes (to be further decimated for LODs) to be employed in a 3D context. Cheers, giovanni ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
[GRASS-user] PLEASE HELP!
From what I can see of GRASS-user postings, most of the discussion is about quite technical aspects of GRASS. Please can someone address my very basic problems? 1 - after running GRASS for about half an hour, the layer selection becomes unresponsive. 2 - I get wired interaction between layers, with activating some switching off the display of others. It is not a masking issue, because selecting and deselecting some layers will make them display properly (but sometimes causes others to disappear). I suspect I may be exceeding a limit on the number of columns or layers, but I have no idea how to check this. I am becoming desparate. Regards Neil Neil Wyatt ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] DTM/DEM to TIN
Hi. I can't find tools to generate TINs, given a certain amount of tolerance, which preserve significative locations (like those obtained by TPI for example) and shapes (in a morphonetric sense) Does the v.triangle add-on accomplish the goal? https://raw.githubusercontent.com/amuriy/GRASS-scripts/a7df12d996abfe6461f509fce6feb6c869af2d5e/v.triangle Mark ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] DTM/DEM to TIN
Hi Mark, thanks for the reply but it's not what I'm looking for. v.triangle is a front-end to Triangle, to generate a Delaunay triangulation on points and, eventually, breaklines. I'm lookink for something that generates a TIN from an elevation grid (raster). giovanni Il 05/dic/2014 14:14 Mark Seibel msei...@gmail.com ha scritto: Hi. I can't find tools to generate TINs, given a certain amount of tolerance, which preserve significative locations (like those obtained by TPI for example) and shapes (in a morphonetric sense) Does the v.triangle add-on accomplish the goal? https://raw.githubusercontent.com/amuriy/GRASS-scripts/a7df12d996abfe6461f509fce6feb6c869af2d5e/v.triangle Mark ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] PLEASE HELP!
On Fri, Dec 5, 2014 at 7:14 AM, Neil Wyatt stub.mand...@gmail.com wrote: From what I can see of GRASS-user postings, most of the discussion is about quite technical aspects of GRASS. Please can someone address my very basic problems? 1 – after running GRASS for about half an hour, the layer selection becomes unresponsive. You have probably a lot of layers in Layer Manager, if you don't need them all, you can right click on the layer and remove, or you can uncheck it. If you have checked a lot of layers, the rendering becomes slow. 2 – I get wired interaction between layers, with activating some switching off the display of others. It is not a masking issue, because selecting and deselecting some layers will make them display properly (but sometimes causes others to disappear). I fixed (hopefully) this weird behavior a couple of weeks ago. So either you can update to a newer version of grass or, as a workaround, it should be enough to make the Layer Manager window larger (vertically), so that you can see all the layers without scrolling. I suspect I may be exceeding a limit on the number of columns or layers, but I have no idea how to check this. I am becoming desparate. Regards Neil Neil Wyatt ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] DTM/DEM to TIN
Thanks for the suggestions. I already had a look at that page, but nothing seems to fulfill my requirements. Using v.random is not a solution. I should select significative points, and significative lines, to feed Triangle. Random selection will probably miss important locations (e.g. peaks, etc.). giovanni 2014-12-05 15:57 GMT+01:00 Vaclav Petras wenzesl...@gmail.com: On Fri, Dec 5, 2014 at 6:01 AM, G. Allegri gioha...@gmail.com wrote: As far as I can see GRASS doesn't provide any ready-to-go tool to generate TINs from grid digital elevation models. I know I can transform a grid to a regular mesh somehow (probably using the Triangle lib for the last step) but I can't find tools to generate TINs, given a certain amount of tolerance, which preserve significative locations (like those obtained by TPI for example) and shapes (in a morphonetric sense). Does anybody has experience on this? The general aim is generating terrain meshes (to be further decimated for LODs) to be employed in a 3D context. I'm not sure if this would fulfill your requirements but I would use v.delaunay [1]. To get the points, you can use v.random [2, 3] or some more clever method. Vaclav [1] http://grass.osgeo.org/grass70/manuals/v.delaunay.html [2] http://courses.ncsu.edu/mea582/common/GIS_anal_grass/GIS_Anal_grinterp1.html [3] http://grass.osgeo.org/grass70/manuals/v.random.html Cheers, giovanni ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user -- Giovanni Allegri http://about.me/giovanniallegri Twitter: https://twitter.com/_giohappy_ blog: http://blog.spaziogis.it GEO+ geomatica in Italia http://bit.ly/GEOplus ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] DTM/DEM to TIN
I've just discoevered r.refine, which seems to do exactly what I need ;) https://github.com/jontodd/r.refine giovanni 2014-12-05 16:21 GMT+01:00 G. Allegri gioha...@gmail.com: Thanks for the suggestions. I already had a look at that page, but nothing seems to fulfill my requirements. Using v.random is not a solution. I should select significative points, and significative lines, to feed Triangle. Random selection will probably miss important locations (e.g. peaks, etc.). giovanni 2014-12-05 15:57 GMT+01:00 Vaclav Petras wenzesl...@gmail.com: On Fri, Dec 5, 2014 at 6:01 AM, G. Allegri gioha...@gmail.com wrote: As far as I can see GRASS doesn't provide any ready-to-go tool to generate TINs from grid digital elevation models. I know I can transform a grid to a regular mesh somehow (probably using the Triangle lib for the last step) but I can't find tools to generate TINs, given a certain amount of tolerance, which preserve significative locations (like those obtained by TPI for example) and shapes (in a morphonetric sense). Does anybody has experience on this? The general aim is generating terrain meshes (to be further decimated for LODs) to be employed in a 3D context. I'm not sure if this would fulfill your requirements but I would use v.delaunay [1]. To get the points, you can use v.random [2, 3] or some more clever method. Vaclav [1] http://grass.osgeo.org/grass70/manuals/v.delaunay.html [2] http://courses.ncsu.edu/mea582/common/GIS_anal_grass/GIS_Anal_grinterp1.html [3] http://grass.osgeo.org/grass70/manuals/v.random.html Cheers, giovanni ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user -- Giovanni Allegri http://about.me/giovanniallegri Twitter: https://twitter.com/_giohappy_ blog: http://blog.spaziogis.it GEO+ geomatica in Italia http://bit.ly/GEOplus -- Giovanni Allegri http://about.me/giovanniallegri Twitter: https://twitter.com/_giohappy_ blog: http://blog.spaziogis.it GEO+ geomatica in Italia http://bit.ly/GEOplus ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] DTM/DEM to TIN
On 05/12/14 16:24, G. Allegri wrote: I've just discoevered r.refine, which seems to do exactly what I need ;) https://github.com/jontodd/r.refine Looks great. Maybe you can convince the author to put the code into the GRASS addons SVN ? Moritz ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] DTM/DEM to TIN
2014-12-05 17:37 GMT+01:00 Moritz Lennert mlenn...@club.worldonline.be: On 05/12/14 16:24, G. Allegri wrote: I've just discoevered r.refine, which seems to do exactly what I need ;) https://github.com/jontodd/r.refine Looks great. Maybe you can convince the author to put the code into the GRASS addons SVN ? I'm tryong to contact him. No reply yet. The GRASS code would need an upgrade because it's based on old APIs... Moritz -- Giovanni Allegri http://about.me/giovanniallegri Twitter: https://twitter.com/_giohappy_ blog: http://blog.spaziogis.it GEO+ geomatica in Italia http://bit.ly/GEOplus ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] DTM/DEM to TIN
Hi Giovanni, A module for this would be really neat! I am not sure if this will be helpful, but here is what I have done in the past. Set your region of interest of course. My notes indicate that I had to add an extra unit to the north and west region (not sure why). r.out.vtk -v input=dem@PERMANENT output=dem.vtk elevation=dem@PERMANENT # 'preserve normals' option kills Meshlab with DEM! r.out.vtk -v input=dem@PERMANENT output=dem.vtk elevation=dem@PERMANENT I then open dem.vtk in Paraview, and run the Delaney 2D filter (default options) save as .PLY file. Next I open the resulting .PLY file in Meshlab and run Quadric based edge collapse strategy - specify desired triangles, preserve normals and I save as .OBJ file. For my needs I choose Preserve boundary of mesh”. Cheers, Jeshua Lacock Founder/Engineer 3DTOPO Incorporated http://3DTOPO.com Phone: 208.462.4171 ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
