Geographic Information Systems Asked by zuzaanto on October 1, 2020
I’t trying to mosaic a GeoTiff raster against another. Initially, they were both georeferenced in WGS-84 CRS.
Using OpenCV, I calculated a homography transformation (a 3×3 projection matrix), that transforms an image to fit the other – I did it using rasters converted to JPEG images. Then, using OpenCV function warpPerspective, I applied my homography to the image and obtained a JPEG mosaic.
Now, I want to apply that transformation matrix to the GeoTiff raster and warp it along with it’s geospatial information. However, I can’t find an GDAL/osgeo function that would do that: gdal.Warp() seems to be doing something else entirely.
So, my question is: is there a function in GDAL that would accept my raster image and my transformation matrix and output the correctly transformed raster with modified geospatial information?
If not, is there a possible workaround to achieve that?
This solution requires using OpenCV 4.x and GDAL in python
You may want to try an affine transform between two images. cv.estimateAffine2D which gives you a 2x3 matrix
Get the transform of the pixel x,y coordinates of the second image to the first
warpedx = A[0,0]*x + A[0,1]*y + A[0,2]
warpedy = A[1,0]*x + A[1,1]*y + A[1,2]
next you can validate by getting the those pixel coordinates and check if they match the original images pixel coorindates
xoff, a, b, yoff, d, e = ds.GetGeoTransform()
xp = a * x + b * y + xoff
yp = d * x + e * y + yoff
if the two points now match, go ahead and align the images and write the image with an updated geotransform
Answered by Evan O'Keeffe on October 1, 2020
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