Re: [GRASS-user] Remove red lines from raster images
Thanks Daniel, I tried your variant with the coarser resolution image. The result is not perfect but good enough for my purpose. Regards, Harry -- View this message in context: http://osgeo-org.1560.n6.nabble.com/Remove-red-lines-from-raster-images-tp5000430p5002604.html Sent from the Grass - Users mailing list archive at Nabble.com. ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
[GRASS-user] Remove red lines from raster images
Dear Users, I have a couple of raster maps (RGB PNG images) where I need to remove the red grid lines. What would be the best way to do this with Grass ? I thought about using r.mapcalc to turn the red pixels (RGB value 255 0 0) to NULL data and then use r.fillnulls to interpolate the NULL data. I now how to do this for elevation data, but how to do this with RGB data ? Thanks for any suggestions ! Harry -- View this message in context: http://osgeo-org.1560.n6.nabble.com/Remove-red-lines-from-raster-images-tp5000430.html Sent from the Grass - Users mailing list archive at Nabble.com. ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
[GRASS-user] Re: How to merge rasters using feathering/blending ?
You can create a buffer zone between your 2 dataset where they merge and set the buffer to null values. Then using r.fillnulls Thanks. This works fine for elevation data but not for satellite imagery. g.region rast=map1,map2 r.series in=map1,map2 out=both_maps method=average Thanks. But this is not really a smooth blending/fading/feathering ? Any alternatives ? Kaipi -- View this message in context: http://osgeo-org.1803224.n2.nabble.com/How-to-merge-rasters-using-feathering-blending-tp6061489p6073011.html Sent from the Grass - Users mailing list archive at Nabble.com. ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
[GRASS-user] Re: How to merge rasters using feathering/blending ?
Gimp is fine if you have a smal number of scenes but I need to process large amounts of scenes where I need an automated way to feather the seam lines. -- View this message in context: http://osgeo-org.1803224.n2.nabble.com/How-to-merge-rasters-using-feathering-blending-tp6061489p6073453.html Sent from the Grass - Users mailing list archive at Nabble.com. ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
[GRASS-user] How to merge rasters using feathering/blending ?
I need to patch rasters containing NULL areas with alternative rasters. I can do this with r.patch but due to different quality/resolution of the rasters this produces prominent seamlines. Is there a way to feather/blend between merged rasters using Grass GIS? Thanks, Kaipi -- View this message in context: http://osgeo-org.1803224.n2.nabble.com/How-to-merge-rasters-using-feathering-blending-tp6061489p6061489.html Sent from the Grass - Users mailing list archive at Nabble.com. ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
[GRASS-user] Re: Limit r.fillnulls to interpolate only small gaps
Thanks for your help ! I tried the r.grow method and it works fine for me. The only problem that remains is that r.fillnulls takes very long. Let me show you my workflow with an SRTM tile as example: r.in.srtm input=S50W075.hgt output=srtm g.region rast=srtm g.region res=00:00:03 r.grow input=srtm output=srtm_grow radius=10 new=9000 r.mapcalc MASK=if(isnull(srtm_grow),0,1) r.fillnulls input=srtm output=srtm_filled_mask r.fillnulls takes 19 minutes to process on Windows. (Grass 6.4 on Vista64, i7 920 with 12GB RAM). The CPU usage is only 13% (of one core) and memory usage is about 77 MB. Even if I put the Grass workspace on a RAM-Disk I have no signifikant performance improvement. On Ubuntu (same hardware) processing time for r.fillnulls is 17:30 min using 100% of one CPU core and 100MB RAM. Any ideas how I can speed up the process ? Thanks. -- View this message in context: http://osgeo-org.1803224.n2.nabble.com/Limit-r-fillnulls-to-interpolate-only-small-gaps-tp6040101p6056317.html Sent from the Grass - Users mailing list archive at Nabble.com. ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
[GRASS-user] Limit r.fillnulls to interpolate only small gaps
Is there an easy way to do this with Grass ? I only want to patch gaps in DEM data up to a certain area size. Thanks ! Kaipi -- View this message in context: http://osgeo-org.1803224.n2.nabble.com/Limit-r-fillnulls-to-interpolate-only-small-gaps-tp6040101p6040101.html Sent from the Grass - Users mailing list archive at Nabble.com. ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] Problem with Lidar Tools
Thanks for your help ! Unfortunately I still don't get satisfying results with the Lidar tools. Here is what I have done so far: - Updated to 6.4 on Windows: v.outlier doesn't work (see my post in Win Grass forum) - Installed Grass 6.4 RC 5 on Ubuntu (Ubuntu package): same results like on Windows Grass 6.3 - Decreased spline steps to 0.04: v.outlier and v.lidar.edgedetection give errors. My results are better the higher the spline steps are ( 20). Brovelli recommends spline step 3 up to 4 times of the planimetric resolution. AFAIK planimetric resolution means points per m². If I have 50 pts/m² this would mean a spline step of 200 ?? With spline steps about 20 I get nice edges and with spline step of 400 complete buildings are detected as edges. - Tried the Lidar demo data (nc_spm_08_2008_may18) and followed the instructions on the Micro-tutorial_for_LIDAR_data_analysis: v.lidar.edgedetection took so long, that I canceled process after 1 h (input file has only 2000-3000 points - so something must be wrong) I have also a problem to understand the definitions of first and last return data. Here is a part of my Lidar data (ASCII format converted from raw LIdar binary): 0 lon lat height intensity last first 1 3360422.27 5825275.62 37.16 255 1 1 2 3360421.94 5825275.60 38.21 56 0 1 3 3360422.48 5825275.60 37.18 255 1 0 4 3360422.17 5825275.58 38.18 141 0 1 5 3360422.65 5825275.58 37.26 255 1 0 6 3360422.84 5825275.56 37.31 255 1 1 7 3360423.05 5825275.54 37.32 255 1 1 8 3360423.36 5825275.52 37.13 255 1 1 9 3360423.06 5825275.50 38.11 12 0 1 10 3360423.60 5825275.50 37.09 255 1 0 11 3360423.70 5825275.49 37.32 255 1 1 First and last returns can be true (1) or false (0) or both. My understanding is, that all points that have first return=true are first returns and all returns that have last=true are last returns. When first and last are true we have a single pulse otherwise we have double pulses. If I understand the microtutorial correctly I need for v.lidar.growing as input the last return single pulses (last=true and first=false) and as first all pulses with first=true. But I get better results when I use as input all last return pulses (only last=true) and as input only the first single pulses (first=true and last=false). I still have the problem that v.lidar.growing does not change categories. Output has only 2 categories - same as output of v.lidar.edgedetection. I have attached two screenshots of my results so far (using the parameters in my first post). I have not yet run v.surf.bspline. http://n2.nabble.com/file/n3928180/lidar_before_after.jpg Classification after v.lidar.edgedetection: http://n2.nabble.com/file/n3928180/edgedetected.jpg Any ideas regarding v.lidar.growing ? Thanks - Kaipi -- View this message in context: http://n2.nabble.com/Problem-with-Lidar-Tools-tp3918684p3928180.html Sent from the Grass - Users mailing list archive at Nabble.com. ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
[GRASS-user] Problem with Lidar Tools
Dear list, I am quite new to Grass and need to generate a DSM from Lidar data. Here is my workflow so far: v.in.ascii input=f:\lidar_test\single.csv output=single fs=, x=1 y=2 z=3 -z -b -t --o v.build single g.region vect=single v.in.ascii input=f:\lidar_test\first.csv output=first fs=, x=1 y=2 z=3 -z -b -t --o v.outlier input=single output=inlier_s outlier=outlier_s thres_o=5 soe=1 son=1 lambda_i=0.1 --o v.outlier input=first output=inlier_f outlier=outlier_f thres_o=5 soe=1 son=1 lambda_i=0.1 --o v.lidar.edgedetection input=inlier_s output=edgedetected see=400 sen=400 lambda_g=0.01 tgh=6 tgl=3 theta_g=0.26 lambda_r=1 --o v.lidar.growing input=edgedetected output=growing first=inlier_f tj=0.25 td=0.6 --o v.lidar.correction input=growing output=classified terrain=terrain sce=5 scn=5 lambda_c=1 tch=2 tcl=1 --o v.lidar.correction input=classified output=classified_it2 terrain=terrain_it2 sce=5 scn=5 lambda_c=1 tch=2 tcl=1 --o v.build terrain_it2 v.out.ogr in=terrain_it2 dsn=F:\lidar_test\terrain_it2 format=ESRI_Shapefile type=point lco=SHPT=POINTZ -e v.lidar.edgedetection classifies the data into cat 1 and cat 2 (=Terrain or Edge ?). This seams to work. The next step is v.lidar.growing. This tool should classify into 4 categories: TERRAIN SINGLE PULSE, TERRAIN DOUBLE PULSE, OBJECT SINGLE PULSE or OBJECT DOUBLE PULSE. But this does not happen. The cats still remain the same (cat1 and cat2) and the output looks identical to the output from v.lidar.edgedetection. v.lidar.growing seams to have no effect. Am I doing something wrong ? I have another problem with the parameters of the lidar tools (although I read Brovellis Managing and processing LIDAR data within GRASS). Can you give me some hints how to adjust the default values to very high res Lidar data (=50 points/m²). I raised see and sen parameter in v.lidar.edgedetection to 400 with the result, that the detected edges are now so wide, that they cover complete buildings. This way I can get rid of the most buildings but the result is not really satisfying and I guess the problem is false classification of v.lidar.growing Let me know if you need more infos. I am using GRass 6.3.0 on Windows. Can I expect improvements switching to 6.4 or switching to Linux ? Thank you very much !! kaipi -- View this message in context: http://n2.nabble.com/Problem-with-Lidar-Tools-tp3918684p3918684.html Sent from the Grass - Users mailing list archive at Nabble.com. ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
