Coded Targets are used for automating the marking and referencing stage for identified points. Coded Targets can be used as plain paper or printed on other materials or with other backings (rubber, plastic, magnetic, vinyl, etc.). If you do get them manufactured ensure they have a very matte top surface.
The easiest way to generate coded targets is to print them from the program. For PhotoModeler version 2018 and later:
Please also see
Sometimes you don’t need the coding (the circular bar code), because you need something smaller or denser, and you will use a different referencing method (like Automatic Referencing). Non-coded targets can be any high-contrast circular dot. These could be created using a printer, a hole punch, a stencil, or any process that produces circles. If they don’t have their own background and will be placed as a small dot directly on the surface, ensure the dot contrasts with the surface (ie. a black dot on a light color surface).
For some applications of high accuracy measurement, where lighting can be controlled, and where a flash will be used on the camera, the targets can be made from a retro-reflective material. This material bounces back a lot of light from a light source in the direction of the camera (hence the flash). Most street and highway signs are made from retro-reflective material. Retro-reflective targets can be seen at greater distances, can be easier to find in noisy environments, and can increase accuracy for high precision industrial measurement. These are not needed in most applications.
Many sign shops can supply white or black 3M retro-reflective sign material and cut circular targets out of it. For retro-reflective coded targets, an advanced and well-equipped sign shop may be able to do them if they can accept pdf files. Here are some other possible sources.
www.retrotargets.com (coded and non-coded)