[gdal-dev] How to use RPC Metadata from NITF Files in a MapServer TileIndex

[Smith, Michael ERDC-RDE-CRREL-NH]

I did originally use -dstalpha. I had dropped it when creating the
geotiffs as I used PHOTOMETRIC=YCBCR as a creation option.

I'll try with -dstalpha and dropping the YCBCR.

Is there a known issue with using the vrts inside a tileindex that makes
it so slow?

--

This is what I used to convert to tif

gdalwarp -rpc -of vrt -overwrite  -t_srs epsg:3857 -r cubic --config
GDAL_CACHEMAX 500 -wm 500 $1 $1.vrt
   gdal_translate -of GTiff -co "TILED=YES" -co "JPEG_QUALITY=95" -co
"COMPRESS=JPEG" -co "PHOTOMETRIC=YCBCR" $1.vrt $1.tif
   gdaladdo --config COMPRESS_OVERVIEW JPEG --config PHOTOMETRIC_OVERVIEW
YCBCR --config INTERLEAVE_OVERVIEW PIXEL $1.tif 2 4 8 16 32


Mike

On 6/17/12 12:38 PM, "Even Rouault" <even.rouault at mines-paris.org> wrote:

>Le dimanche 17 juin 2012 18:24:29, Smith, Michael ERDC-RDE-CRREL-NH a
>écrit :
>> I have a large number of NITF JP2K files. These files have IGEOLO
>>metadata
>> to the second accuracy so reprojecting these images leads to poor
>>results.
>> The images also have rpc metadata and using the -rpc option in gdalwarp
>> reprojects them quite well. These files are source epsg:4326 and need to
>> be reprojected to epsg:3857 for display.
>> 
>> I had orginally thought to just create a vrt for each ntf file with the
>>rpc
>> information but a tileindex of the vrts is dramatically slower to
>>display
>> in MapServer (for a 1:8000 scale area, from ~ 1 sec to over 10 min). It
>> does reproject correctly though. Obviously not practical.
>> 
>> I then thought to reproject the vrts to an actual format (geotiff). The
>> problem is that the black bounds (which should be nodata but are just
>>near
>> black areas) get expanded and aren't handled even when using the
>>nearblack
>> utility on the resulting geotiffs.
>> 
>> The best option (if possible) would seem to use the source nitf files
>>but
>> force gdal to use the rpc information to reproject (without having to go
>> through the vrt process). Perhaps a CPL config option that could be set
>> inside mapserver?
>
>Did you use the -dstalpha option of gdalwarp, so that the areas in the
>reprojected image that are not part of the source image are marked with a
>0 
>alpha value ? -dstnodata could also do it.
>
>> 
>> Other suggestions are welcome.
>> 
>> Mike
>> 
>> --
>> Michael Smith
>> michael.smith at usace.army.mil
>> US Army Corps
>> Remote Sensing GIS/Center