I'm not a professional archaeologist and this is going to sound silly.
Cloth stores catering to quilters sell clear lucite rulers marked off in
1" grids with tic marks every 1/8"; they're about 24 x 6", and they are
calibrated with fanatical accuracy because real hot-dog quilt patterns
have no tolerance for error.  The rulers are thick and need to be placed
with the markings down to eliminate parallax error.  I expect they would
look peculiar in a photograph taken from any distance, but impressive in a
closeup.
 
S. Boling
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