Daniel N. Olson, M.S.M.E., P.E.
Do you have photographs in your file that depict information that is not visible today? Do you need to know the length of skid marks that have worn away? Do you need to know the accurate position of an item that has since been moved?
If your photographs depict some points that are still visible today or if you have photographs of your scene taken from different angles that depict points in common, we can help you extract the information that you need using photogrammetry.
Photogrammetry, the art and science of making measurements from photographs, is done with the aid of the computer. The photographs are scanned and digitized and points common to the photographs are referenced to each other. The computer program processes information about the relative position of the points and information about the camera to develop a three dimensional model. The model can be scaled and oriented so that measurements can be taken between referenced points.
What if we don't know much about the camera? If there are enough points on the photograph that are still at the scene today, we can process the old photographs along with the new photographs taken with a known camera. The settings and parameters for the old camera can be calculated with data from the new photographs.
Rules of thumb to help you decide if your photographs are useful: