Mono image NRW
Mono-image NRW (or mono-image process NRW) is a method with which very precise accident sketches of the North Rhine-Westphalia police are produced as a replacement for the hand-drawn sketches that are considered inadequate.
It is a photogrammetric measuring method that can be used by any officer.
At the scene of the accident, the officers take photos of the accident to document the damage and the location, on which the largely chalked-out traces of the traffic accident are clearly reproduced.
Before this, so-called reference points were marked on the road (usually with “colored crosses”) or pointer-target boards were set up, which are then clearly visible in the measurement photo. At least five routes between the reference points are measured on the roadway and are used in further processing as actually known variables that are transferred to the photography.
In the further processing, the photos are rectified with special computer software and linked via two identical reference points of each square, so that a flat image plan is created as a top view of the accident site.
Any number of routes and objects can then be measured specifically from this photo-realistic sketch without having to actually measure this dimension on the roadway.
This procedure has its limits in bad weather conditions or in traffic accidents that involve extensive lanes over a long distance. For large accident sites, the NRW police use a similar photogrammetric method, the Rollei-Metric method of the State Criminal Police Office of North Rhine-Westphalia . For this purpose, the track position is photographed from an optimal location, namely usually from a helicopter hovering over the accident site.