Introducing FlowTrace: Physics-Based Reconstruction of Blood Spatter Patterns with Curved Trajectories

Straight-line reconstruction software (HemoVision, FARO Zone 3D, HemoSpat, Leica Map 360) helps visualize the location of bloody events in the 3D crime scene; they facilitate data processing, documentation, and presentation of results. However, they assume blood drops travel in straight lines. This assumption can lead to overestimating the height of the region of origin of a blood spatter by as much as 3 feet in certain cases, and there is no simple way to know which reconstruction cases may be affected. This hands-on workshop introduces FlowTrace, a complementary tool that verifies whether straight-line assumptions are appropriate for your specific case.

Built on peer-reviewed research in Forensic Science International (Attinger et al., 2019, doi:10.1016/j.forsciint.2019.02.003), FlowTrace can function independently or integrate with existing workflows. The software imports straight-line project files or your measurements of stain shapes and positions, then applies ballistic physics including gravity, air drag, and drop deformation. It outputs nested 3D probability volumes (confidence intervals corresponding to 1, 2, and 3 standard deviations) representing the reconstructed areas of origin from where the spatter originates. These results can be integrated into 3D reconstruction workflows, and reveal when straight-line results are valid versus when curved trajectories alter conclusions.

The workshop will demonstrate FlowTrace's integration with HemoVision, and discuss possibilities for integration with other reconstruction software. The workshop progresses through four phases: