Chris, Try passing gdalwarp -et 0.0
I am also suspicious of doing compression with the warp. you might want to do that as a second step Brian On Wed, 2011-08-31 at 23:16 -0700, heng.feng wrote: > Hi, > > I have used the (OSGeo4W) GDALWARP command to warp some height data image > files (NTv2 transformation). When displaying one warped height data in our > own application, there appear to be visible tiles on the image and some > misalignments exist between those square tiles (chunks). > > After warping, I did make some conversion on the height data from the > original format (ERDAS Imagine) to another format, which can be accepted by > our own application. However, I think this tiling effect is not caused by > the format conversion, but most likely by something in the GDALWARP command. > The reason for saying this is that I have done the same format conversion on > the original height data without warping and there are no tiling effects at > all for the converted height data when shown in our application. As > attached, please see the two screenshots for the same area of the height > data being displayed in our application. One is with warping while the other > is without warping. > > I seem to remember that the GDALWAP command does the chunk warping. Could > this be the reason why? > > The GDALWARP command I have been using is something like this: > > gdalwarp --config GDAL_CACHEMAX 250 -wm 250 -co COMPRESS=LZW -co BIGTIFF=YES > -co TILED=YES -multi -overwrite -s_srs "+proj=tmerc +lat_0=0 +lon_0=12 > +k=1.000000 +x_0=4500000 +y_0=0 +ellps=bessel +datum=potsdam > +nadgrids=c:\height \BETA2007.gsb,null +units=m +wktext" -t_srs "+proj=utm > +datum=WGS84 +zone=32" "c:\height\test.img" "c:\height\test.tif" > > I have tried the GDALWARP command on the same height data by taking away all > the above command options and got the same tiling effect. Also I have > managed to open the warped height map data (tif format) in another GIS > application and could see the tiling effects as well although the effect is > not as visible as seen in our own application. I think this is because the > color interpretation type is gray in that warped height tif file. > > The other thing worth mentioning is: with the same warping and conversion > process, lower resolution height data (or much smaller height data) do not > seem to have such visible tiling effects. > > Anyway, does anyone here have any clue about this? And is there any way to > get rid of the tiling effects in the warped height data? > > Many thanks & BR, > Chris Feng > > > > > > -- > View this message in context: > http://osgeo-org.1803224.n2.nabble.com/GDALWARP-Chunk-Problem-Tiling-Effect-tp6749055p6749055.html > Sent from the GDAL - Dev mailing list archive at Nabble.com. > _______________________________________________ > gdal-dev mailing list > gdal-dev@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/gdal-dev _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev