[gdal-dev] gdalwarp -rpc and RPC_DEM results and .TIL files

[Ivan Lucena]

Hi there,

Does anybody has ever tried to orthorectify an "Ortho Ready Standard" 
QuickBird image with .TIL files?

To whom might be interested, there is a couple of sample data on 
digitalglobe.com and you can always find DEM on USGS.COM.

Contrary to GDAL standards :) in most of those sample dataset the .RPB 
file are not directed associated to the Geotiff file. Like in

some_file_name.tif
some_file_name.rpb

That is usually the case when the scene covered is too big and the data 
provider decided to dived it on tiles.

The .TIL file describe the offsets in lines/pixel/X/Y of each of the 
tiles and the .RPB is related to the .TIL file. Like in:

some_file_t1.tif
some_file_t2.tif
some_file_t3.tif
some_file_name.til
some_file_name.rpb

Since GDAL does not support the .TIL file, what one needs to do is to 
use gdalbuildvrt to create a VRT to represent the same tilling as the 
.TIL file.

At that point it is still not ready to do orthorectification yet because 
gdalwarp doesn't seems to digest the combination .VRT .RPB.

some_file_name.vrt
some_file_name.rpb

But that is just a matter of converting the VRT to GTIFF and go ahead 
and run:

gdalwarp some_file_name.tif the_output_name.tif -rpc -to 
RPC_DEM=the_dem_file.tif -t_srs EPSG:32610

But after all that I can't see much more accuracy when overlaying a 
vector road map on top of the original non-orthorectified than over the 
orthorectified output. It is a little bit better in some places but 
worse in some others.

I found much better results with datasets without tilling. I mean, 
without .TIL files. Just one GTIFF and one .RPB

Has anybody had that same experience?

Do we have plans to support the .TIL file in GDAL?

Best regards,

Ivan