Abstract: Described herein is a computer implemented method. The method includes including accessing data describing a set of original elements, wherein each original element has an original bounding box, processing the set of original elements to identify a set of pre-existing element overlaps, accessing data describing a set of updated elements; and identifying a first undesirable collision. Identifying the first undesirable collision includes determining that a first current element overlap exists and determining that the first current element overlap is an introduced overlap. Determining that the first current element overlap is an introduced overlap includes determining that there is no pre-existing overlap in respect of a first original element that corresponds to the first updated element overlapping a second original element that corresponds to the second updated element.

Abstract: A digital processing system for, a method, implemented on a digital processing system of, and a non transitory machine readable medium containing instructions that when executed implement the method of: automatically selecting one or more complementary images from a set of provided images for use with triangulation and determination of 3D properties of a user-selected point or geometric feature of interest, such as information on the slope (also called the pitch) and one or more dimensions of a roof of a building. The one or more complementary images are selected automatically by using an optimality criterion, also called a complementarity criterion.