Devices, systems, and methods obtain two sets of images of an object, each of which was captured from a respective viewpoint; identify pixel regions in the two sets of images that show reflections from a light-modulating device that were reflected by a surface of the object; calculate respective surface normals for points on the surface in the pixel regions; calculate, for each viewpoint, respective unscaled surface coordinates of the points based on the respective surface normals; calculate, for each viewpoint, a respective initial scale factor based on the respective surface normals and on decoded light-modulating-device-pixel indices; calculate, for each viewpoint, scaled surface coordinates of the points based on the respective initial scale factor and the respective unscaled surface coordinates of the viewpoint; and calculate, for each viewpoint, a respective refined scale factor by minimizing discrepancies among the scaled surface coordinates of the points on the surface.
