Hi Pradeep,
to calculate the destination coordinates of the two points, you can call 
gdaltransform with the same gcp parameters as gdal_translate und gdalwarp 
before. Gdal uses the same algorithm for transforming raster and vector data.

Martin

Von meinem iPhone gesendet

Am 26.02.2020 um 17:00 schrieb Pradeep kumar <parthivprad...@gmail.com>:


Hi All,

I am georeferencing aerial images with gcps using gdal_translate and gdalwarp. 
Before georeferencing image(warping) I would like to check quality and final 
result on a control_point cp (eg disabeld gcps). Therefore I would like to 
calculate the coordinates in destination image for a independent control_point 
based on the interpolation method (n-order, helmet and spline) which is NOT 
used by warping itself.  Afterwards compare positions with estimated 
coordinates of that cp.

Example:
Lets say, I have 10 gcps. I take 8 gcps, using `-order n` generate a `model`.  
Then predict destination values for rest of the two control points using this 
`model`. Finally compute shift between predicted and actual values for these 
control points.

Could you please let me know if any gdal tool does this? Can any one give some 
insight how to implement this in python?

I have checked following stack exchange issues.
1. 
https://gis.stackexchange.com/questions/225931/python-gdal-how-to-obtain-dx-dy-residual-errors-for-gcps-after-gdalwarp-usage
 (self written n-grad interpolation, is there any validaton form offical gdal?)
2. http://osgeo-org.1560.x6.nabble.com/GCPs-to-geo-transform-td3771045.html
3. https://gis.stackexchange.com/questions/102111/preserve-gcps-after-gdalwarp

--
Best Regards,
Pradeep Gulla
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