Bloodstains-3D Scanning and Photogrammetry

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3DForensics
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Bloodstains-3D Scanning and Photogrammetry

Post by 3DForensics » Fri Aug 07, 2009 8:06 pm

I thought I would post this as an example of how a very simple use for 3D scanning and photogrammetry can come into play for bloodstain pattern analysis.

If you look at the attached image and imagine you were tasked with documenting the evidence in the photograph, you would soon find a very tedious task of taking measurements of a piece of evidence that you don't necessarily want to touch.

Non-contact methods are best when evidence is "fresh" and in this particular image, a 3D scanner or photogrammety would be preferred simply because it would be extremely tedious and time consuming to take hand measurements for all the droplets and accurately place their size, shape and positions relative to one another.

Traditionally, photographs are taken and a right angle scale is placed in the photograph. However, the generated mesh allows for measurements to be taken of the drops and stains relative to one another and their size and shape accurately plotted. The other thing to consider is that the scale method only works on a flat surface and many times, there can be several perpendicular and odd shaped surfaces where a scale can not give an orthorectified view.

On a personal note, I think that is is surprising that not many people are trained in 3D techniques or at least how to take photos so they can effectively "lock in" all the 3D data in their photographs. I think it would make their job a lot easier and provide for better documented evidence.
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3DForensics
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Re: Bloodstains-3D Scanning and Photogrammetry

Post by 3DForensics » Sun Aug 09, 2009 12:21 am

Here is the point cloud. I turned down the scan density, but you get the picture.
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