PLY (Stanford Polygon Format)

PLY is a Stanford University format, invented for the results of three-dimensional scanning. It is arranged as simply as can be: the header describes which properties vertices and faces have, and then come the data themselves. Thanks to that PLY became a working format in science and in point cloud processing — it is read by MeshLab, CloudCompare, Open3D, ParaView and Blender.

Its main difference from STL is support for colour right in the vertices. Where STL delivers only shape, PLY carries the colouring as well, so a city model stays readable: the types of development are visible by colour without assigning materials by hand.

The export contains the buildings of the selected area: outlines are extruded upward by height tags, and the colour of the development type is transferred into every vertex by averaging the colours of the adjacent faces. Coordinates are in meters from the centre of the area and the base is flat — there is no relief and no georeferencing in the model. By default the file is written in binary form (more compact and faster to read); the text variant is only needed if you intend to look through the contents by eye.