Forensic Mapping

What is it:

Forensic Mapping is the process of accurately mapping evidence at a scene to produce an accurate scale map or diagram. The data collected can often be cruical in proving causation. Mapping evidence

Scene measurements may be obtained using a variety of methods such as a simple tape measure, or using sophisticated electronic measuring devises. Crime scene map
Crime Scene Map - (click image for larger view)

The most commonly used methods utilize electronic Theodolites, GPS and Photogrammetry.

Once the measuring data has been obtained, scale scene diagrams are produced using computer assisted drawing, (CAD) software.

The scene diagrams produced are typically topography plans, however when required cross sectional plans are also utilized. This may be in order to show gradients or sight distance.

3D animations are also being produced from the measurement data.

These new methods make collection and map production quicker and more accurate, however not everyone has access to, or is capable of operating the complex electronic equipment used today.

NZCI employs qualified experts in this area to enable companies that require detailed investigations to utilize the benefits that forensic mapping offers.

When to use it:

Forensic mapping can be utilized for crash scene measurements to enable crash analysis and a variety of calculations to be completed.

These may be:

  • Speed from tyre friction marks
  • speed from vault - where a vehicle is driven off an embankment
  • Vechicle positioning on a road. ie is the vehicle in the correct lane
  • Collision dynamics
  • Roadway gradients
  • Critical curve speeds of corners

It can also be use when an investigator is attempting to find out exactly what vehicles have done during a crash, such as rolling, or rotating laterally.

Ffloor plan layouts can be completed to illustrate where the seat of a fire started and spread too, or where surveillance cameras are required to cover a car yard etc.

The diagrams produced are also professional and accurate for presenting in court hearings. They make what maybe complicated to portray in words easy in diagrammatic form so judges, adjudicators, juries etc can vissualy see what a witness may not be able to clearly explain. Elevation diagram
Elevation diagram - (click image for larger view)

What NZCI Uses:

NZCI primarily use an electronic theodolite when obtaining measurements from scenes. Sokkia Electronic Theodolite
Sokkia Electronic Theodolite

This method utilizes an electronic Theodolite to accurately measure and capture the data the instruments data recorder.

The data is then transferred from the data recorder into a computer and scale diagrams produced through CAD software. Scaled Topography Scene Diagram
Scaled Topography Scene Diagram - (click image for larger view)

NZCI use SOKKIA electronic Theodolites supplied by Optical Services. Auckland as our preference when conducting field work throughout New Zealand.