orientation marks on test bits

[jimgriff]

Greetings
One often sees markings on "things" being tested which look like a circle with a cross through it (vertically and horizontally) and each quarter is either black or white. I understand these are orientation marks for photographic purposes.
Does anyone know what these are called? Do they have a name?
Where might I get 4 of them for a small photo project?
thanks in advance
Jim

[green granite]

In the weapons industry they were just known as datum marks/points, they were used for analysing speed and other parameters from film or video , we used to just paint them on.

Try using a paint programme to make them and print them out, I doubt you will buy them anywhere, but I might be wrong.

[Jaguar Pilot]

jimgriff,

I do professional drawings for private clients within the aviation industry.
I don't use paint because it is not accurate enough. To do these jobs properly requires the use of industry-standard graphics software.

I could draw you one.

JP

[jimgriff]

Thanks all for the answers. I could I guess make my own on the PC but thought these things might have been 2 a penny for sticking on dispensable kit (bombs and the like).

I'll get some round stickers from the local print firm and print my own.
Once again many thanks

Jimgriff

[Double Zero]

Datum markings

We always used square painted markings on the aircraft ( Harrier 1 & 2 ), stores to be released such as bombs were usually painted in black & white quadrants.

We asked the test range/s what would be easiest to see / film with kine-theodolite tracking cameras, the reply was " don't bother, any aircraft always looks black against the sky ".

The datum points were useful for on-board cameras though.

[green granite]

Indeed Double Zero the only point of the marks were so that the person analyzing the film on the x/y plotter could bring the cross hairs of the cursor back to roughly the same place on the weapon/aircraft in successive frames so as to get a reasonably accurate velocity etc. In my days when computers filled whole rooms and ran on valves, most of the results were hand plotted on graph paper and the errors smoothed out by eye. The edges of the aircraft tended not to be always well defined all the way through the film, twas exceeding annoying to get half way through a job and find the datum point had gone. Even worse when the only equipment was a projector and a piece of paper to plot with.

I used to use the more precise marks for ground trials where the lighting could be better controlled, the image to frame size larger (usually) and perhaps a 1000fps film speed to ensure the image remained reasonably sharp, or as you said for on board high speed cameras.

Sorry guys wallowing in nostalgia at the moment, I'd better shut up I think.