See where people walk with heatmaps and paths

Counts say how many. Paths say where. During a run CV-Scope stores up to ten positions per second for each tracked object, one per processed frame. They are anonymous points on the floor, never images. They feed a heatmap and the paths in video review.

Step 1. Check that paths are stored

1. Open Settings.
2. In the Storage panel, Store sampled trajectories should be ticked. It is on by default.
3. If you change it, click Save changes. The setting applies to runs that start afterwards.

With trajectory storage off, only events and track summaries are kept. The heatmap and the paths in video review then stay empty.

Step 2. Read the heatmap

1. Open a finished run. For example, open the experiment Count the middle line from guide 02 and click Results in the Runs table.
2. Open the Tracks and heatmap tab.
3. Trajectory heatmap (sampled ground positions) divides the picture into a grid and shades each cell by how many positions were recorded there. The camera image is not shown under it. The number of samples is shown below it.

In the corridor sample, 207 positions were stored. The busiest cells lie along the foot of the back wall, where people crossed the room, and in the lower middle, where people walked close to the camera.

Track statistics beside it tells how well tracking went:

Step 3. Replay with paths

1. Click Video review at the top of the results page.
2. Click Play. The video plays with the scene drawn over it. Use −1 frame and +1 frame to step, and the speed list to slow down.
3. Tick or untick the overlays: Zones and gates, Trajectories, Track ids and Event markers.
4. The timeline under the video has a mark for each event. Click a mark, or a row in the Events list on the right, to jump to that moment.

Video review needs the source video, so it works for runs on video files. CV-Scope does not record video from live cameras. For those runs the page shows the event list only.

Step 4. Follow one track

1. In the Events list, click a row of the person you want to follow. The video jumps to that moment.
2. Click the track number in that row, such as #3. Only that track’s trail is drawn now. Play the video to watch that one person.
3. Click Show all tracks to draw every path again.

Track numbers are anonymous. They start again at 1 in every run and cannot link a person across runs or cameras.

Paths during a run

The Scene Builder draws a short trail behind each tracked object while a run is live. In the inspector, the Overlays section switches Trajectories, Boxes, Track ids and other drawings on and off. It changes only what you see, not what is recorded.

Next

Guide 16 turns positions into metres, so paths get a length and people a walking speed.