Re: [GRASS-user] New addon: r.denoise. Denoise topography including SRTM
Hi Frank, Frank Broniewski wrote: but could you provide some hints on general memory usage? Xianfang said that the out of memory message came during the triangulation stage of denoising. The triangulation is carried out by triangle.c, which he did not write. I don't know how triangle uses memory. Perhaps Hamish does? Xianfang also recommended denoising small areas, perhaps with overlap, and seeing how well they can be merged. Cheers John -- Dr John Stevenson Postdoctoral Research Associate School of Earth, Atmospheric and Environmental Sciences Williamson Building (Room 2.42) University of Manchester Manchester M13 9PL, UK tel. +44(0)161 306 6585; fax. +44(0)161 306 9361; john.steven...@manchester.ac.uk ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] New addon: r.denoise. Denoise topography including SRTM
On Thursday 17 September 2009 14:13:45 John A Stevenson wrote: Hi Frank, Frank Broniewski wrote: but could you provide some hints on general memory usage? Xianfang said that the out of memory message came during the triangulation stage of denoising. The triangulation is carried out by triangle.c, which he did not write. I don't know how triangle uses memory. Perhaps Hamish does? Xianfang also recommended denoising small areas, perhaps with overlap, and seeing how well they can be merged. Cheers John John, thank you very much for your kind help. I hope I can find some time for tests in the next few weeks. I will publish my results here on the list so everyone has something from it Greetings Frank ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] New addon: r.denoise. Denoise topography including SRTM
John wrote: Xianfang said that the out of memory message came during the triangulation stage of denoising. The triangulation is carried out by triangle.c, which he did not write. I don't know how triangle uses memory. Perhaps Hamish does? No idea. Hamish ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] New addon: r.denoise. Denoise topography including SRTM
Hi John, I want to try your module with my srtm data, but I always get out of memory messages. Maybe I am just to ambitious with my region settings :-) , but could you provide some hints on general memory usage? Or should I program a script for a moving window so I get smaller regions? Are there any problems then on the connecting borders, e.g. differnently smoothed surfaces at the edges? // messages and script call ... r.denoise in=dgm out=dgm_denoise iterations=5 threshold=0.99 ... n1: 5 n2: 50 Read Model... Triangulation... Error: Out of memory. Many thanks Frank On Monday 17 August 2009 17:35:15 John A Stevenson wrote: Hi, I've uploaded a new module, r.denoise, to the addons repository. The module can be used to remove noise/speckle from DEMs including SRTM data. Removing noise can improve the results from other modules e.g. r.watershed, r.slope.aspect. Compared to mean/median filtering with r.neighbors, r.denoise makes much smaller changes to the data and is able to preserve sharp edges. The module is most easily installed on grass-6.5.svn via the command: g.extension r.denoise however, being a shell script, it can also be downloaded and copied to a directory on the path. Further information: Addons page: http://grass.osgeo.org/wiki/GRASS_AddOns#r.denoise Article in press in Geomorphology describing use of the denoising algorithm on Lidar, TOPSAR and SRTM. http://dx.doi.org/10.1016/j.geomorph.2009.07.006 Enjoy, John ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] New addon: r.denoise. Denoise topography including SRTM
Hi Frank Frank Broniewski wrote: I want to try your module with my srtm data, but I always get out of memory messages. Maybe I am just to ambitious with my region settings :-) , How big a region are you using? Have you had any luck testing it on a smaller region? I have only ever run out of memory on a 24 million point region, but can happily (if slowly) denoise it if I halve the resolution (~6 million points). I have 4Gb RAM. but could you provide some hints on general memory usage? I've emailed Xianfang Sun who wrote the denoising part, (I just wrote the GRASS interface) and will let you know what he says. Or should I program a script for a moving window so I get smaller regions? Are there any problems then on the connecting borders, e.g. differnently smoothed surfaces at the edges Each of the cells moves individually based on their neighbouring points, so the edges would be smoothed differently. The magnitude of the differences would be very small, but many algorithms e.g. slope, shaded relief are very sensitive to them, so I think that they would show up. Cheers John -- Dr John Stevenson Postdoctoral Research Associate School of Earth, Atmospheric and Environmental Sciences Williamson Building (Room 2.42) University of Manchester Manchester M13 9PL, UK tel. +44(0)161 306 6585; fax. +44(0)161 306 9361; john.steven...@manchester.ac.uk ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] New addon: r.denoise. Denoise topography including SRTM
On Wednesday 16 September 2009 12:47:52 John A Stevenson wrote: Hi Frank Frank Broniewski wrote: I want to try your module with my srtm data, but I always get out of memory messages. Maybe I am just to ambitious with my region settings :-) , How big a region are you using? Have you had any luck testing it on a smaller region? I have only ever run out of memory on a 24 million point region, but can happily (if slowly) denoise it if I halve the resolution (~6 million points). I have 4Gb RAM. but could you provide some hints on general memory usage? I've emailed Xianfang Sun who wrote the denoising part, (I just wrote the GRASS interface) and will let you know what he says. Or should I program a script for a moving window so I get smaller regions? Are there any problems then on the connecting borders, e.g. differnently smoothed surfaces at the edges Each of the cells moves individually based on their neighbouring points, so the edges would be smoothed differently. The magnitude of the differences would be very small, but many algorithms e.g. slope, shaded relief are very sensitive to them, so I think that they would show up. Cheers John Hi John, thanks for your answers so far. The region was quite large, a good part of europe and I only have 1GB of RAM. I chose a much smaller subregion and the algorithm worked without a problem. It was really nice to see that I was able to calcualte a good flow direction grid from a former problematic region now with reasonable results. If there are differences at the borders, I will have to see what I can do about it. Some low memory swith like the r.watershed module has would be nice ... but I have no clue how to implement this. But I haven't investigated yet if the mdenoise script has some more options. Thanks Frank ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
[GRASS-user] New addon: r.denoise. Denoise topography including SRTM
Hi, I've uploaded a new module, r.denoise, to the addons repository. The module can be used to remove noise/speckle from DEMs including SRTM data. Removing noise can improve the results from other modules e.g. r.watershed, r.slope.aspect. Compared to mean/median filtering with r.neighbors, r.denoise makes much smaller changes to the data and is able to preserve sharp edges. The module is most easily installed on grass-6.5.svn via the command: g.extension r.denoise however, being a shell script, it can also be downloaded and copied to a directory on the path. Further information: Addons page: http://grass.osgeo.org/wiki/GRASS_AddOns#r.denoise Article in press in Geomorphology describing use of the denoising algorithm on Lidar, TOPSAR and SRTM. http://dx.doi.org/10.1016/j.geomorph.2009.07.006 Enjoy, John -- Dr John Stevenson Postdoctoral Research Associate School of Earth, Atmospheric and Environmental Sciences Williamson Building (Room 2.42) University of Manchester Manchester M13 9PL, UK tel. +44(0)161 306 6585; fax. +44(0)161 306 9361; john.steven...@manchester.ac.uk ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
