Following:
- Learning by Training: 3-day workshop in Brussels in September 2024
- Investigation Residency in Berlin & Critical Climates
- Training. From the ground to Space: taking & analysing samples, using remote data, maps and satellite images - and There and Back
- Training on "Bioassay Test with seed to expose toxicity from Water sample"
We now know that:
- Our current Photomacrographic Scale is made with a lack of precision
- We need a square Photomacrographic scale to provide visual evidence on the roots of the seeds for the ecotoxicity test.
- We need L Photomacrographic Scale for other visual evidences in the field (wastes, microplastics, etc.
Like this ugly inaccurate example:
We need a 10 cm square that forms a grid made up of 1 cm by 1 cm meshes graduated to the nearest millimeter.
The contrast between the colors and materials should also allow you to take photos on it with plant roots from freshly sprouted seeds.
The Designed by the American Board of Forensic Odontology (ABFO) No. 2 Style Photomacrographic Scale inspires me a little, especially its colour shades.
But it’s not perfect and many other versions exist in different countries.
A good fact sheet that both sets out the specs and reviews different productions, right down to the details of the lines, from millimetre measurements to the thickness of the printed lines. This comparative study also gives specs for industrial production 
Here are 2 useful readings:
- https://imagingforensics.com/2014/12/forensic-rulers/
- https://forensicreader.com/rulers-and-scales-types-uses/
We must also make and provide a Grey Card, like this one, for setting up the digital camera to help take the photo of the evidence.
After some quick and dirty test it seems to be feasable using FreeCad or LibreCAD for Photomacrographic scale.
But Design matters!
So I’m opening this topic in the idea to start collaboration on this task.
cc @Studio.DPI
