AR markers

Ar markers are much like QR codes, a black and white (or other high contrast color combination) pattern that stores information. In AR they're used as markers that denote positions of 3D models.

Builtin Barcode Markers

These are built into ar.js (or rather artoolkit / arcore ar.js uses). They are generally reliable and will provide stable models even on older devices. Artoolkit Barcode Markers collection (github).

Custom AR Pattern Markers

Any simple pixer art image can be converted into a marker. A marker should be:

not simetric
very simple (16x16 px)
have a border in high contrast with the image

The best method was to draw 16x16 pixel art, then upscale to 1024x1024 and use the pattern trainer on ar.js github to train it and generate a patt file and an image. The patt files it generates are a simple text format file that denotes the value of each pixel. Checking the file visually for likeness with the input raster image is a good manual check to see if the training went well.

The stability of these markers is a bit worse then the builtin barcode markers but can be trained and tweaked for usability.