[gdal-dev] Sub: Gdal, leave one out method with GCP'S (Interpolation Equation)

[Martin.Franzke at telekom.de]

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 <parthivpradeep at 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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