Orthorectification of QuickBird with GCP in ENVI

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Last Post 02 Feb 2009 02:50 PM by anon

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anon

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02 Feb 2009 02:50 PM
Hi everyone, I am having some difficulty with orthorectifying a QB image with ground control points and I will try to summarize the available data sets and the problems I encountered. I have an un-orthorectified QB image with the associated RCP file. I also have the DEM of the same area. In order to have a more precise image, I wanted to run orthorectification with ground control points. I selected GCP's and saved them as pts file and run the orth. with DEM. The result was an image with all values being 255. Also I was not able to open the pts file later to run the process again. Everytime I select set of control points and run orthorectification, all I have is an image with single value. I feel like I am missing a step, so I really appreciate any comments on what might be the problem. Thanks, archeo

MariM

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03 Feb 2009 09:18 AM
Do you get a result if you run the orthorectification without GCPs? If you also get a bad result from this, then it may be a problem with the data. You may wish to contact technical support about this. If the bad results only happen when using GCPs, you may need to look at the GCPs for accuracy. You can have a single GCP that is incorrectly entered, or the projection of the GCPs is not what ENVI is reporting. This is most common when the GCPs are collected in a projection that is not Geographic.

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