[gdal-dev] GDALWARP Chunk Problem (Tiling Effect)
Heng.Feng at AIRCOMINTERNATIONAL.COM
Thu Sep 1 02:36:53 EDT 2011
Thanks for your prompt reply, Brian.
I did try GDALWARP command on the same height data without the compression option and the tiling effect still exists, but I will try the option "-et 0.0" and let you know it goes.
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From: Brian Case [mailto:rush at winkey.org]
Sent: 01 September 2011 07:27
To: Heng Feng
Cc: gdal-dev at lists.osgeo.org
Subject: Re: [gdal-dev] GDALWARP Chunk Problem (Tiling Effect)
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
On Wed, 2011-08-31 at 23:16 -0700, heng.feng wrote:
> 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
> +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:
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