How Scoring Works
Your drawing is compared to the actual country border using
Intersection over Union (IoU) — the overlap
between your shape and the real one, divided by their combined area.
IoU scoring: We sample 5,000 points across the region and check how many
fall inside both your drawing and the actual border. The more overlap and the less
extra area, the higher your score. A perfect trace scores 1,000 pts.
Actual border
Your drawing
Key Takeaways
- Every vertex counts — more points along the border means a tighter fit
- Shape AND position matter — a correct shape in the wrong spot still scores low
- Size matters — too big or too small reduces overlap significantly
- Use hints if stuck — a small penalty is better than a wild guess
- Multi-polygon: use Ctrl+click for countries with islands
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