Photo Calibration Marks

[Sasquatch]

I've often seen photos showing "photo calibration markings" on prototype airplanes, like those shown at this site:

http://modelingmadness.com/scotts/decal ... sbd001.htm

Can anyone tell me exactly what the purpose of these sorts of markings is? Is if for exact focusing or something of that nature?

Thanks!

--Tom

[Old SAR pilot]

Tom,

If I recall correctly, they are focus points, or aiming points if you will, for various types of optical instrumentation used during aircraft testing.

[Cvairwerks]

Never known them to be used for focus points. We use them for movement reference. Simply knowing the physical size of the markings, the analysis people can determine movement data from film and video measurements. Some of the data that is routinely gathered is rate, distance, time and motion vectors.