Keyframes are modelled as VidiCore thumbnails. Thumbnails are low-resolution images of a specific frame of the video. They are referenced on an item via a timecode which denotes the image’s position on the timeline of the video.
VidiCore posters also are images grabbed at a certain timecode position. The difference to thumbnails is that posters usually have the full hires video resolution whereas thumbnails are smaller, mostly the size of the proxy video.
Thumbnails and posters do not have any relation to timecode-based metadata. If you want to ensure that a thumbnail is present for the first frame of each timespan you can ask VidiCore to create thumbnails at exactly those positions by specifying a list of timecodes in a thumbnail job.
Comparing It To Worker-Based VPMS
In worker-based VPMS keyframe and thumbnail images only could be attached to VPMS shots which were used for modelling timecode-based metadata.