Re: [OSSIM] Calculating RPCs

[Brent F. <bf...@ge...>]

Chris,

   As far as I know, gdalwarp will use only a single value (0?) for 
height when using RPCs to rectify an image. so if the geographic area 
imaged has a lot of relief, the resulting ortho image may not be too 
accurate.  Orthoigen will access DEMs to produce a better result.  On 
the other hand I see that all of your GCPs have an elevation of 0, so if 
ossim-orthoigen does not have a DEM to use, the two programs should 
produce the same result.

   The problem may be in the RPC calculation...

Best Regards,
Brent Fraser


On 4/26/2011 7:12 AM, Goo Creations wrote:
> Hi Garrett
>
> Sorry about this back-and-forth thing. I'm trying now for weeks, and I 
> can't manage to get it working.
>
> I've uploaded the test stuff to:
> http://www.foxhat.org/test.tar.gz
> OR
> https://rapidshare.com/files/459272465/test.tar.gz
>
> This example uses OTB wrappers for the RPC calculations. To compile:
> ccmake .
> make
> ./rpc
>
> The raw.tif will be used as input image, the GCPs are in gcps.points.gcp.
> Running ./rpc will use these files to create RPC.txt and raw.geom
> The data from RPC.txt was then copied to raw.RPB (since gdal requires 
> a RPB file for the coeffcients)
>
> Then I used the following to apply the RPCs:
>  gdalwarp -wo "METHODE=RPC" -rpc raw.tif out.tif
>
> And:
> ossim-orthoigen --utm raw.tif out.tif
>
> Both of them result (more-or-less) in the same strange warping.
>
> The GCPs were carefully selected by hand, all evenly distributed over 
> the entire image, with one GCP in (or near) each corner.
>
> I'm using Ossim version 1.8.6
>
>
> Thank you Garrett for all the time and effort!!
>
> Chris
>
>
>
> On Tue, Apr 26, 2011 at 2:21 PM, Garrett Potts <gc...@ma... 
> <mailto:gc...@ma...>> wrote:
>
>     Hello Chris:
>
>     This going back and forth doesn't seem to be working.  What I
>     think will be best is if we can have 1 test image and the process
>     you are using to create the RPC model.  I will then modify it to
>     calls directly into the ossim core engine that we have.  I am not
>     sure what version of OSSIM you are using, ... etc.  It's best for
>     us to do a test and then give you the result.
>
>
>     Take care
>
>     Garrett
>
>     On Apr 26, 2011, at 5:12 AM, Goo Creations wrote:
>
>>     Hi all
>>
>>     I've used OSSIM to calculate the RPCs, based on a number of GCPs
>>     (using EstimateRPCSensorModelExample.cxx).
>>     I've then copied all the data to an RPB file and used GDAL to
>>     orthorectify the image (gdalwarp -wo "METHOD=RPC" -rpc raw.tif
>>     ortho.tif).
>>     I've attached the RPC file calculated by OSSIM, the RPB file I've
>>     created and a jpg from the output image.
>>     The image is strangely warped, and I don't know why.
>>
>>     I've done the same process with "QuickBird: Standard Satellite
>>     Imagery" available at
>>     http://www.digitalglobe.com/index.php/70/Product+Samples.
>>     This image orthorectified "perfectly", without any warping.
>>
>>     Hence I believe that the RPCs calculated by OSSIM might not be
>>     100% accurate, or maybe I'm wrong. Does anyone know why this
>>     warping occurred? Is there any other software I can use to test
>>     if the RPCs are correct?
>>
>>     Thanks
>>     Chris
>>     <RPC.txt><raw.RPB><ortho2.jpg>------------------------------------------------------------------------------
>>     WhatsUp Gold - Download Free Network Management Software
>>     The most intuitive, comprehensive, and cost-effective network
>>     management toolset available today.  Delivers lowest initial
>>     acquisition cost and overall TCO of any competing solution.
>>     http://p.sf.net/sfu/whatsupgold-sd_______________________________________________
>>     www.ossim.org <http://www.ossim.org>
>>     Ossim-developer mailing list
>>     Oss...@li...
>>     <mailto:Oss...@li...>
>>     https://lists.sourceforge.net/lists/listinfo/ossim-developer
>
>
>     ------------------------------------------------------------------------------
>     WhatsUp Gold - Download Free Network Management Software
>     The most intuitive, comprehensive, and cost-effective network
>     management toolset available today.  Delivers lowest initial
>     acquisition cost and overall TCO of any competing solution.
>     http://p.sf.net/sfu/whatsupgold-sd
>     _______________________________________________
>     www.ossim.org <http://www.ossim.org>
>     Ossim-developer mailing list
>     Oss...@li...
>     <mailto:Oss...@li...>
>     https://lists.sourceforge.net/lists/listinfo/ossim-developer
>
>
>
> ------------------------------------------------------------------------------
> WhatsUp Gold - Download Free Network Management Software
> The most intuitive, comprehensive, and cost-effective network
> management toolset available today.  Delivers lowest initial
> acquisition cost and overall TCO of any competing solution.
> http://p.sf.net/sfu/whatsupgold-sd
>
>
> _______________________________________________
> www.ossim.org
> Ossim-developer mailing list
> Oss...@li...
> https://lists.sourceforge.net/lists/listinfo/ossim-developer