Explainer · Inspection technology
How do you track each egg on a conveyor in real time?
Tracking an egg means recognising, frame by frame, that the same shell is still the same egg as it moves along the conveyor. Vigiovo segments the eggs in every frame and links each one to the previous frame by nearest neighbour, predicting its position with constant velocity. Dirt and crack measurement runs only at each egg's three checks.
Updated · 4 min read
What does it mean to track an egg on the conveyor?
Tracking means keeping an egg's identity from one frame to the next. Without it, the same egg would appear as a new egg in every frame, and measurements taken at different moments could not be combined into a single decision.
Vigiovo splits the work into two parts. Colour segmentation finds the shell of every egg and runs on each frame, because it is cheap. Dirt and crack measurement is the expensive part, and it runs only when an egg reaches one of its checks.
How is an egg linked to the next frame?
Each egg detected in a frame is linked to the egg in the previous frame closest to where it was predicted to be. The prediction uses the speed the egg already had: if it was moving right, the system expects to find it further right in the next frame.
While an egg moves smoothly, the prediction lands close to its real position and the link is straightforward. The table summarises what runs on every frame and what runs only at certain steps.
| Step | What it does | How often |
|---|---|---|
| Colour segmentation | Finds each egg's shell in the image | Every frame |
| Linking between frames | Matches each egg to the previous frame by nearest neighbour | Every frame |
| Dirt and crack measurement | Measures the egg against its own shading surface | Three times per egg |
| Voting | Rejects the egg if the defect shows up in 2 of 3 checks | After the 3 checks |
What happens when two eggs are close together?
Touching eggs are separated before tracking, by watershed, so each one becomes its own object. When two predictions point to the same place, the link is settled by a deterministic tie-break: the rule is fixed, and the same recording always produces the same links.
That predictability matters for audits. Processing the same recording again gives every egg the same path and the same decision, so the per-egg record can be checked without surprises.
Tracking also cannot fix errors in segmentation. If an egg is not found reliably in one frame, that error carries into the link, which is why the final decision rejects an egg only when 2 of 3 measurements agree.
How many measurements per frame does the line need?
In Vigiovo's video demonstration, the cost is about 2 measurements per frame, with about 45 eggs on screen. Each egg is measured 3 times, with the checks at least half a radius of travel apart, like the 1/3, 2/3 and 3/3 checks on a quality-control panel.
Average latency is about 11 ms per frame, and throughput is about 90 frames per second on a single CPU core at 960×540. The detail is in latency and throughput. These figures come from the synthetic demonstration; your line depends on the camera and on how many eggs are visible.
What can tracking not see?
Tracking only follows what the camera sees. Hairline cracks, interior defects and the part of a shell hidden by another egg never appear in any frame, and no link between frames recovers them.
When segmentation cannot close a reliable outline, the egg gets no class. It is marked as an unverified egg and goes to manual review, as described in unverified eggs.
Frequently asked questions
Is tracking eggs the same as grading them?
- No. Tracking only keeps each egg's identity from frame to frame. The class comes from the dirt and crack measurements taken at the three checks, using fixed thresholds and the 2-of-3 vote. An egg can be tracked successfully and still end up unverified.
How many eggs can Vigiovo follow at once?
- In the video demonstration, about 45 eggs appear on screen at the same time, at about 11 ms per frame on average. That is a test scenario, not a guaranteed limit. Your line's capacity depends on the camera, the resolution and how densely eggs sit on the conveyor.
Does the spacing between checks depend on the belt speed?
- Spacing is measured in egg radii, not in seconds, so the same configuration works with cameras of different resolutions. The checks are at least half a radius of travel apart, which makes sure each measurement sees the egg in a different position.
Sources
How Vigiovo helps
Vigiovo grades eggs on the conveyor as clean, dirty, cracked or unverified, in real time, with deterministic computer vision: every decision comes with the measurements behind it, on an ordinary CPU.