1. A computer-implemented method for densifying and colorizing a point cloud representation of a physical surface, comprising: receiving a set of measured surface points representing a surface sampling of a three-dimensional physical surface, each measured surface point having a position in a three-dimensional coordinate reference frame; receiving at least one image acquired by an image acquisition unit and representing an image sampling of the physical surface; the image sampling of the physical surface in the at least one image at least partially overlapping the surface sampling of the physical surface; the image sampling of the physical surface in the at least one image being denser than the surface sampling of the physical surface; each image being a digital image comprising a plurality of pixels each having a color and an image position in the image; receiving image metadata associated with each image, the image metadata including an estimate of position and orientation of the image acquisition unit in the coordinate reference frame at the time the image acquisition unit acquired the image to which the image metadata corresponds, the image metadata further including calibration parameters for the image acquisition unit; and for each image: isolating from the set of measured surface points a subset of measured surface points comprising those measured surface points that are within a field of view of that image; using the image positions of the pixels in that image, the subset of measured surface points and the image metadata associated with that image to calculate colorized implied surface points; wherein: each colorized implied surface point has a position in the coordinate reference frame; each colorized implied surface point is associated with a corresponding pixel; and each colorized implied surface point has the color of its corresponding pixel; wherein for each image, using the image positions of the pixels in that image, the subset of measured surface points for that image and the image metadata associated with that image to calculate colorized implied surface points comprises, for each pixel with which a colorized implied surface point is associated: using the image position of that pixel and the image metadata associated with that image to calculate an estimated projected position of that pixel on the physical surface in the coordinate reference frame; identifying a corresponding neighborhood of nearest measured surface points to the estimated projected position of the pixel on the physical surface; using the neighborhood of nearest measured surface points and the image metadata associated with that image to determine the position of an implied surface point associated with that pixel; and assigning to the implied surface point the color of the corresponding pixel to form the colorized implied surface point.