Information about mask file combination method missing?

Question

Currently there are two types of masks in motion. A "fixed mask" and an internal "smart mask". In the sections "smart_mask_speed" and "mask_file" in the "Motion Basic Feature Guide" I did not find information about the combination of both.

1) What happens if both masks are activated? Are they e.g. binary "AND" combined?

2) mask_file could be grey-valued (not only binary). (Is the "smart mask" also grey-valued?) In that case, how are they combined then?

Environment

Motion version:	3.2.6
ffmpeg version:
Libraries:	ffmpeg, mysql, postgresql
Server OS:

-- OliverLudwig - 23 May 2006

Answer

The two masks are ANDed.

The fixed mask is given by the mask file and a grey tone image. Most people use back and white only. Black is the areas that are ignored.

The smart mask is a feature that you enable and then Motion takes care of the rest. So there is no such thing as a grey smart mask. Smart mask is a dynamic mask that build up in the places in the image where motion is continuously detected. Such as a branch of a tree moving in the wind. Once the wind is gone the smart_mask fades away also. The smart_mask is not saved in any files. It is kept in a buffer in RAM and needs to rebuild itself if you restart Motion.

-- KennethLavrsen - 23 May 2006