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OSSIM Notes

Thursday, 25 August 2005 04:05
OSSIM is awesome image processing for remote sensing data. I've been using it for a few years now. It provides tools to perform orthorectification and other nice things in GIS.

OSSIM Wiki UserDocs

Format ossim data types within your VS debugger
Add the following to your autoexp.dat under the [Visualizer] section. This modification will tell VS how to expand some of the OSSIM classes during a debug session. VERY HANDY.
For VS2005, you can find the autoexp.dat within the "C:\Program Files\Microsoft Visual Studio 8\Common7\Packages\Debugger\autoexp.dat" folder.
The autoexp.dat is read everytime you start a debugging session within VS, so simply paste, save, and debug.
(Course you'll want to save off the orginal autoexp.dat!)
Also, I've had trouble in the past using an external editor...not sure why, but when I opened in VS2005 and made the changes they stuck.


Notes for OSSIM on Mac's XCode
First checkout the instructions on the OSSIM planet wiki(MacOSX Build).

Steps to build on MacOSX using packaged deps.
#!/bin/bash
 
cd /Users/Shared/Development
wget http://ossim.telascience.org/ossimdata/MacOSX/ossim_dependencies.tgz
svn co https://svn.osgeo.org/ossim/trunk .
cd /Users/Shared/Development/ossim_dependencies/lib
ranlib *.a
cd ../nuiSDK/lib
ranlib *.a


List of SVN and CVS repositories needed to build OSSIM using the trunk of all source:
# here are my old notes, they don't apply anymore.
#!/bin/bash
 
cvs -d :pserver:
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 :/cvs login
cvs -d :pserver:
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 :/cvs co ossim
cvs -d :pserver:
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 :/cvs co libnitf
cvs -d :pserver:
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 :/cvs co libwms
cvs -d :pserver:
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 :/cvs co ossimPlanet
cvs -d :pserver:
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 :/cvs co ossimplanet_qt
cvs -d :pserver:
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 :/cvs co ossim
cvs -d :pserver:
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 :/cvs co ossim_contrib
cvs -d :pserver:
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 :/cvs co ossim_plugins
cvs -d :pserver:
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 :/cvs co ossim_qt
cvs -d :pserver:
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 :/cvs co ossim_test_suite
cvs -d :pserver:
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 :/cvs/osg co osgEphemeris
cvs -d :pserver:
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 :/cvs/DWMake co DWMake

The easiest way to get to the metadata from an OSSIM chain is to grab the image to view transform for the chain and look at the theImageProjection data memeber. (I use this for debugging within my programming ide)

What determines resolution level for OSSIM igen spec files
The r-level is computed within the ossimImageRenderer::fillTile (line 837). It computes the image to view scale by transforming the four corners of the requested rect. Getting the length in image space and the length in view space. to compute the image to view scale.

Then ossimImageRenderer::fillTile computes the needed level using the following math:
double averageScale = (imageToViewScale.x + imageToViewScale.y)/2.0;
   long   closestFitResLevel = (long)floor(log(1.0/averageScale)/
                                           log(2.0));   
   ossim_uint32 resLevel = closestFitResLevel<0?0:closestFitResLevel;
So for OSSIM to pull from reslevel 1 (note reslevel 0 is nominal), spec the product.projection.meters_per_pixel_x/y to something a bit more than 2*nominal.
Thought: this calculation is done for each tile requested.... the image2view scale doesn't change for a product between getTile requests... Each corner is being transformed twice (lineSampleToWorld and worldToLineSample) with a lot of floating point math in there (sqrt,log,etc). (I'm always watching for speed improvements) {/highlight}

Notes on QT and imagelinker.
Qt4 with Visual Studio
When building Qt 4.2 with MSVC 2005 and Service Pack 1 beta I get compile errors, how can I fix these?

Katrina Imagery Warehouse: The Inside Story

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Last Updated on Monday, 16 July 2007 06:59