Parent Topic: <A href="http://www.pcigeomatics.com/cgi-bin/pcihlp/GCPWORKS|Theory">Theory</a><hr>
<H4>Satellite Ortho Model</H4>
The Satellite Ortho Model is the geometric model used in the PCI PACE Satellite
Ortho and DEM package.  In GCPWorks, it is only enabled when the user 
selects the &quot;Satellite Ortho Correction&quot; Mathematical Model from the 
GCPWorks Setup panel.  It should be noted that the residual errors reported in
GCPWorks are in PIXEL unit on the raw image, assuming the input geocoded 
coordinates are correct.  This is equivalent to setting ERRUNIT=PIXEL
inside SMODEL program of satellite ortho package.<p>
The polynomial transformation method, in comparison, does not reflect
the distortions due to the image acquisition and relief displacements.
The polynomial transformation method is limited to small areas with 
flat terrain and requires a lot of GCPs.
The PCI satellite ortho model only requires a minimum of three to four accurate
GCPs for visible images (such as SPOT and Landsat), and seven accurate GCPs for
RADAR images (such as ERS and RADARSAT). <p>
The geometric modelling was developed by Dr. Thierry Toutin, at the Canada 
Centre for Remote Sensing.  <p>
The model requires a minimum of 4 and 7 GCPs for VIR (such as Landsat,
SPOT, IRS) and SAR images, respectively.   However, if the GCPs are
not very accurate, the user should collect at least 6 and 12 GCPs for
VIR and SAR images, respectively.
                                                                                   
More details on satellite ortho model can be found in the Registration 
Scenarios section.  Also see the Satellite Ortho &amp; DEM manual, and the
Orthorectification and DEM Extraction chapter of the Using PCI Software
manual.
<P>
<hr>
Parent Topic: <A href="http://www.pcigeomatics.com/cgi-bin/pcihlp/GCPWORKS|Theory">Theory</a><br>
<a href="http://www.pcigeomatics.com/dev_corner/pcihlp_gateway.html">About PCI Help Gateway</a>