US Patent 10553020 Shadow mask generation using elevation data

A method can include determining, based on elevation data of a geographic region corresponding to a location at which an image was captured and a solar elevation angle at a time the image was captured, whether each pixel of the image is a shadow or a non-shadow to create a shadow mask of the image, generating an eroded shadow mask that includes the shadow mask with a specified number of pixels from a perimeter of each shadow in the shadow mask changed to respective values corresponding to non-shadows, generating a dilated shadow mask that includes the specified number of pixels in the shadow mask changed to values corresponding to shadows, and refining the shadow mask using the eroded shadow mask and the dilated shadow mask to create a refined shadow mask.