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Examples
Below are examples of forensic projects done with PhotoModeler. Click on the image for a larger view.
Also see the PhotoModeler Scanner Forensics Examples.
| Crime Scene Measurement Project |
PhotoModeler can be used for a number of forensic measurement and diagramming tasks. One such task is the diagramming of a crime scene where the only remaining evidence is a single photograph or video frame. Using PhotoModeler, and its various tools designed for this sort of project, important measurements can be extracted long after the scene is gone.
In this simulated crime scene project, a single image from a surveillance camera was used. The parameters of this camera are not known so we used the Inverse Camera process in PhotoModeler. Using assumptions of parallel and perpendicular lines we set up Constraints applied to the marked lines (as shown in the first image). When the project was solved, the camera parameters (such as its position, its angles, and its focal length) were solved along with the positions of the lines in 3D space. Additional detail was then added to the model using Surfaces and Surface Draw. After adding scale to the model, it was ready for measurement and for export to a diagramming package such as Crimezone for further enhancement. While this project was based on an unknown camera and a scene from the past, this method can also be used as a quick way for a forensic technician or officer to diagram a scene where they were present to take the photograph with their own camera.
| Measurements from Accident Scene Photos |
PhotoModeler is a valuable tool for measuring distances between objects in accident scenes where injuries occur and liability must be determined. This mock accident scene project involved a ladder leaning against a tree branch near hydro lines.
The scene was meant to simulate the remaining evidence following the accidental electrocution of a person who was trimming tree branches. In the process of determining liability, there was a question as to the location of the ladder in relation to the tree and hydro lines. The photos used for this project were taken with an "unknown" 35mm auto-focus camera to simulate the type and quality of photos that most likely would be provided to the consultant.
The result was a model of the scene that could be measured within PhotoModeler or be exported to a CAD program for further analysis. Most of the measurement checks provided values that were within +/- 2 inches. For this application this would be considered acceptable and was in line with the expected results. Accuracy would be improved if more camera parameters were known and the photographs were taken from better angles.
This project was conducted by Dan Mills of DCM Technical Services. DCM can be contacted at dmills@eol.ca.
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