Rectify photos with the help of photogrammetry. So you get a completely level view of one side of a building for example. So you can take the result for measurements of this building. You can export the result as a picture or as a DXF file. If you take a photo of a rectangle what you get is a trapezoid. The program will rectify the trapezoid so that it will be a rectangle again and the scale of the original object will be restored. This means equal lengths in reality will become equal lengths on the rectified photo. You only need to specify 4 points in the photo which form a rectangle in reality. You can let the program render an even wider area as spanned through these 4 points. It is also possible to erase areas in the rectified image. Simply draw over them in the program. The program can recognize lines in the rectified image and save the lines as a DXF file. So you can work further with the rectified drawing in your CAD application.