engleski

Establishing a datum point at the crime scene using a single GPS device: detecting and minimizing error in a simulated case example

The Global Positioning System (GPS) is a standard tool for establishing a datum point at the outdoor crime scenes that lack fixed objects or landmarks. However, GPS is prone to multiple errors that occur with a different intensity in different time intervals and degrade the accuracy of the positioning. In the present simulated case, we have examined the error of establishing a position using a single hand-held GPS unit, as well as the efficiency of reducing the error by averaging multiple coordinates collected at the same spot through the time. The results have shown great variations between the actual position and position obtained by GPS through collection time, demonstrating that a single GPS reading is not a reliable tool for establishing an accurate datum point in a forensic context. However, when a sufficient number of fixes is averaged, periodical variations of GPS error less affect accuracy, and error linearly decreases. To minimize the error of positioning in forensic cases, we suggest developing a model for GPS application that considers the acceptable degree of error, available equipment, the specificity of the crime scene location and defining a detailed workflow for reducing the error with the averaging method.

forensic science ; crime scene ; Global Positioning System ; mapping ; fixed point ; datum point

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