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

[Dmitriy Baryshnikov]

Hi Ivan,

I orthorectify such products with comparable with Envi results. But, 
exist TIL driver usually have SRS WGS84 and output raster lost in 
resolution on Y Axis. I correct driver and commit it (see ticket #3482 
for details). Everything should be OK.
Also you need to add RPC_HEIGHT with some value to correct geoid.
http://translate.google.ru/translate?sl=auto&tl=en&js=n&prev=_t&hl=ru&ie=UTF-8&eotf=1&u=http%3A%2F%2Fgis-lab.info%2Fqa%2Forbview3-ortho-gdal.html&act=url

Best regards,
     Dmitriy

09.02.2013 3:33, Ivan Lucena пишет:
> 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
>
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