Preparing DEM in order to image Orthorectification

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Last Post 15 Nov 2008 11:18 AM by anon

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anon

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15 Nov 2008 11:18 AM
Normal 0 false false false MicrosoftInternetExplorer4 I have a doubt about the georeference of the DEM when it will be using in order to orthoretification a image. In few words, the DEM must be register with the reference data, like a image reference or Ground control Point, or must be register with the image that is want to correct. For example, in the case of ASTER image and the DEM generated with their stereo pair bands, the DEM is register with the image that is want to correct, but when the DEM is acquired form other resource, what needs to be done ?

MariM

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17 Nov 2008 08:43 AM
If you want to have accurate elevation information for your GCPs when orthorectifying, you should make sure the DEM locations match those of the input file to be orthorectified. You should not necessarily need to register the DEM to the image, but you should make sure the GCPs selected include the accurate location on the DEM so that you use the correct elevation value. To help you locate yourself on a DEM, you might overlay some vector data onto it - something like a roads layer or known GPS locations to orient yourself.

Deleted User

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19 Nov 2008 11:11 AM
Thank mminari , but yet I have the doubt in the sense that if my DEM match with my input image, that is the image that a want to correct, this DEm will have the same error position that the image, and will not match with my GCP´s, that have the correct position coordinates ......this makes sense?...thank again

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