Hello all, I have been using gdalwarp to georeference sensor data with geolocation arrays.
I have observed that GDAL assigns values to pixels that clearly fall outside the geolocation footprint, producing some funny artifacts at the image edges. For example, see the image here<https://pasteboard.co/K69DUni.png>. (Sensor data over Google satellite basemap; red dots are geolocation points.) Notice how the data values are 'extruded' from the edges. This occurs with various interpolation methods (all the ones I tried), including nearest neighbor, average & bilinear. Why does this happen? How can I go about fixing this? Ideally, any pixel in the output grid which lies more than 1 pixel width from any of the geolocation points (red dots) would be assigned to no-data. My code is very straightforward, basically I open the raw sensor image & geolocation array (a.k.a. input geometry map or IGM) with GDAL & then assign geolocation metadata to the sensor image before warping: # Geolocation domain metadata geoloc_metadata = { 'SRS': WGS84_UTM16N.ExportToWkt(), 'X_BAND': '1', 'X_DATASET': str(igm_img_file), 'Y_BAND': '2', 'Y_DATASET': str(igm_img_file), 'PIXEL_OFFSET': '0', 'LINE_OFFSET': '0', 'PIXEL_STEP': '1', 'LINE_STEP': '1', } # Set geolocation domain metadata on dataset to be warped dn_img_ds.SetMetadata(geoloc_metadata, 'GEOLOCATION') x_min, y_min = igm[:2].min(axis=(1,2)) x_max, y_max = igm[:2].max(axis=(1,2)) # warp_options = gdal.WarpOptions(warpMemoryLimit=) warped_ds = gdal.Warp(f'/warped.tif', dn_img_ds, outputBounds=(x_min, y_min, x_max, y_max), xRes=1.0, yRes=1.0, resampleAlg='near', dstSRS=WGS84_UTM16N, srcNodata=None, dstNodata=-9999, multithread=True, targetAlignedPixels=True, outputType=get_gdal_dtype(np.int16), geoloc=True) Any insight would be much appreciated. Cheers! — Brendan Heberlein Research Intern, BS Townsend Lab University of Wisconsin - Madison
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