HemoVision Validation Data November 2021
HemoVision is a software package that automates bloodstain impact pattern analysis. Ten impact patterns with known area of origin (AO) coordinates were created and used to assess HemoVision’s accuracy. Moreover, HemoVision’s results were compared to those of HemoSpat and the manual tangent method. HemoVision achieved the lowest average error and performed significantly better than the manual tangent method and the automated tangent method at a 5% significance level. The archive file contains ten folders, one for each impact pattern. Each folder contains two subfolders: a HemoSpat subfolder containing pictures of selected bloodstains with reference scales and reference plumb lines, and a HemoVision subfolder containing a single overview image (encompassing the complete impact pattern) and several detailed close-up images of impact stains. Additionally, an ‘info.txt’ file is included with each pattern, containing true AO coordinates, overview marker coordinates, and manually measured stain coordinates.
Steps to reproduce
The impact patterns were created using an impact device resembling a large mousetrap, consisting of a hammer, rubbers bands, and a container for blood. The hammer was pulled back and fixed using a piece of string, after which 5mL of porcine blood was pipetted into the container. As the blood had been frozen, it was first thawed and heated to around 37° while stirring to prevent clotting. The string was then cut, creating an impact. Once created, the impact patterns were left to air-dry, after which they were photographed using a Canon EOS 600D.