CFP CFP Scene Reconstruction & Photogrammetry 1 — Questions and Answers
Question 1: What is photogrammetry as applied in forensic crime scene investigation?
- The science of obtaining reliable measurements and 3D spatial data from two-dimensional photographs (Correct answer)
- The process of developing film in a laboratory
- A method for enhancing blurry crime scene images
- The use of special filters to improve photograph contrast
Correct answer: The science of obtaining reliable measurements and 3D spatial data from two-dimensional photographs
Forensic photogrammetry extracts precise measurements and spatial relationships from photographs, enabling accurate scene reconstruction without re-visiting the scene.
Question 2: Why is it mandatory to include a scale reference in forensic close-up photographs?
- To allow accurate measurement of evidence size and spatial relationships when the photograph is analyzed later (Correct answer)
- To make the photograph look more professional
- To satisfy camera manufacturer requirements
- To indicate which photographer took the image
Correct answer: To allow accurate measurement of evidence size and spatial relationships when the photograph is analyzed later
A scale reference provides a known measurement within the image, enabling accurate size determination and proportional analysis of evidence during reconstruction.
Question 3: What is a 'total station' and how is it used in crime scene reconstruction?
- An electronic surveying instrument that measures angles and distances to create precise coordinate data for scene mapping (Correct answer)
- A police command post at a major incident
- A camera system that takes 360-degree panoramic images
- A specialized darkroom for processing forensic photographs
Correct answer: An electronic surveying instrument that measures angles and distances to create precise coordinate data for scene mapping
A total station uses laser distance measurement and angle detection to produce accurate X/Y/Z coordinates for every point of interest at a scene.
Question 4: When photographing skid marks for traffic accident reconstruction, what camera angle best captures length and direction?
- A low, oblique angle parallel to the road surface, supplemented by overhead or elevated views (Correct answer)
- Directly overhead only
- A 45-degree angle from any direction
- Close-up macro photography only
Correct answer: A low, oblique angle parallel to the road surface, supplemented by overhead or elevated views
Low oblique angles reveal skid mark texture and direction while elevated views establish length and trajectory relative to road features.
Question 5: What is the purpose of an 'overall' photograph in crime scene documentation for reconstruction?
- To establish the spatial context of the scene, showing the relationship between all major elements before close-up photography begins (Correct answer)
- To document the photographer's equipment
- To capture only the victim's location
- To photograph the outside of the building from the street
Correct answer: To establish the spatial context of the scene, showing the relationship between all major elements before close-up photography begins
Overall photographs orient viewers to the entire scene, establishing spatial relationships that allow reconstruction analysts to understand context.
Question 6: What does 'rectified photography' correct for in forensic scene documentation?
- Lens distortion and perspective convergence so that parallel lines in the scene appear parallel in the image (Correct answer)
- Overexposed areas in crime scene photos
- Color inaccuracies caused by artificial lighting
- Motion blur from hand-holding the camera
Correct answer: Lens distortion and perspective convergence so that parallel lines in the scene appear parallel in the image
Rectification removes perspective and lens distortion, producing geometrically accurate images from which true measurements can be extracted.
CFP CFP Scene Reconstruction & Photogrammetry 1
What is photogrammetry as applied in forensic crime scene investigation?