What is track_id?

[photoscan_user]

In docs I can see only:
track_id Track index in PointCloud.Point and PointCloud.Projection
http://www.agisoft.com/pdf/photoscan_python_api_1_4_2.pdf

Is it just unique indentificator of point or is it related to some consept of 'track'?

Also what is meant by `Point valid flag`?

[Alexey Pasumansky]

Hello photoscan_user,

tracks (chunk.point_cloud.tracks) in Python API represent all matching points found, even if there are no 3D locations estimated for them. Whereas each element from the point_cloud.points is linking to one of the point_cloud.tracks, so len(tracks) >= len(points).