1. A computer-implemented method for generating a depthmap for images of structures in a geographic area, the method comprising: dividing the geographic area into a plurality of coarse cells, wherein each of the plurality of coarse cells is visible in no more than a first threshold number of a plurality of low-resolution images; generating, using multi-view stereo processing, a set of coarse three-dimensional (3D) points of one or more structures in each of the plurality of coarse cells based on the plurality of low-resolution images associated with a corresponding one of the plurality of coarse cells; dividing the geographic area into a plurality of fine cells, wherein each of the plurality of fine cells is visible in no more than a second threshold number of a plurality of high-resolution images; generating, using multi-view stereo processing, a set of fine 3D points of the one or more structures in each of the plurality of fine cells based on at least a portion of the set of coarse 3D points generated for a corresponding one of the plurality of coarse cells and based on the plurality of high-resolution images associated with a corresponding one of the plurality of fine cells; generating a mesh model of the one or more structures in each of the plurality of fine cells based on the set of fine 3D points for a corresponding one of the plurality of fine cells; identifying one or more of the mesh models visible in a corresponding one of the plurality of high-resolution images; and generating a depthmap for each of the plurality of high-resolution images based on the identified one or more mesh models visible in a corresponding one of the plurality of high-resolution images, wherein each of the plurality of low-resolution images comprises metadata that includes a visible surface region estimate of the geographic area, and wherein the visibility of each of the plurality of coarse cells is based on the visible surface region estimates of corresponding ones of the plurality of low-resolution images, and wherein each of the plurality of coarse cells is visible in one of the plurality of low-resolution images if the visible surface region estimate of the one of the plurality of low-resolution images intersects with a corresponding one of the plurality of coarse cells.