Tip 63: Two Styles of Surface Drawing in PhotoModeler
PhotoModeler’s Surface Draw is a useful tool for doing 3d ‘tracing’ on a surface in a single photo. Typically in photogrammetry to create a 3D point one needs to mark or identify the image of that point in two or more photos – so it can be computed by triangulation/intersection. There are a couple of cases where 3D data can be created from marks in just a single photo. Surface draw is one such case – you can draw/mark points in a single photo and if a 3D surface exists in the area, 3D data can result.
Surface Draw is like ‘tracing’ an object but the result is full 3D – points or lines. PhotoModeler has two styles of Surface Draw. The difference in these styles is based on where the 3D points are located relative to the one or more surfaces under the drawing.
In the first style, all points are created in the plane of the surface of the first point drawn in one Surface Draw Line. This style is useful if you need to draw in areas of the photo where no surfaces exist. Example, tracing out a stained glass window where no surface exist on the window, but surfaces for a neighbor wall do.
In the second style, the points are associated with the surface under each mark in the line. That is, the tracing follows the surface. This style is useful for complex shaped surfaces where you want the tracing to be ‘true’ to the surface. A setting needs to change in PhotoModeler to get this style. This style may interact a bit more slowly if there are many complex surfaces in the project.
Watch the tip video to see how the two modes of Surface Draw are controlled and the results: