11. Quiz: IoU and Overlap Limits

Intersection over Union (IoU)

We know the IoU is given by the area of: intersection/union. The next couple questions will test your intuition about what values IoU can take as it compares two bounding boxes.

Two bounding boxes. Intersection in dark green and union in light green.

Two bounding boxes. Intersection in dark green and union in light green.

Imagine you’re comparing a ground truth box to a predicted box. If you want your predicted box to be as close to this ground truth box as possible, what would you want the IoU to be?
SOLUTION: 1

What is the lowest value IoU can have?
SOLUTION: 0

IoU Values

The IoU between two bounding boxes will always have a value between 0 and 1 because, as two boxes drift apart, their intersection approaches 0, but if two bounding boxes overlap perfectly their IoU will be 1.
So, the higher the IOU the more overlap there is between the two bounding boxes!

In the next video we will see how Non-Maximal suppression uses the IOU to only choose the best bounding box.

Examples of maximum and minimum IoU values between two boxes.

Examples of maximum and minimum IoU values between two boxes.

Next Concept