IoU (Intersection over Union) in Computer Vision - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does IoU stand for in computer vision?

IoU stands for Intersection over Union. It is a metric used to measure the overlap between two areas, often between predicted and actual bounding boxes.

beginner

How is IoU calculated?

IoU is calculated by dividing the area of overlap between the predicted bounding box and the ground truth bounding box by the area of their union.

beginner

Why is IoU important in object detection?

IoU helps to evaluate how well the predicted bounding box matches the actual object. A higher IoU means better prediction accuracy.

intermediate

What is a typical IoU threshold used to decide if a detection is correct?

A common IoU threshold is 0.5. If the IoU between predicted and ground truth boxes is above 0.5, the detection is considered correct.

beginner

What happens to IoU if the predicted box and ground truth box do not overlap?

If there is no overlap, the intersection area is zero, so IoU is 0, indicating no match between predicted and actual boxes.

What does the numerator in the IoU formula represent?

A The area of overlap between predicted and ground truth boxes

B The total area covered by both boxes

C The area of the predicted box only

D The area of the ground truth box only

The numerator is the intersection area where both predicted and ground truth boxes overlap.

If IoU = 1, what does it mean?

A No overlap between boxes

B Partial overlap between boxes

C Perfect overlap between boxes

D Boxes are completely separate

IoU of 1 means the predicted box perfectly matches the ground truth box.

Which IoU value usually indicates a good detection in object detection tasks?

A 0.1

B 0.9

C 0.3

D 0.5

An IoU of 0.5 or higher is commonly used as a threshold to consider a detection correct.

What does the denominator in the IoU formula represent?

A Area of union of predicted and ground truth boxes

B Area of predicted box only

C Area of overlap

D Area of ground truth box only

The denominator is the union area, which is the total area covered by both boxes combined.

If two boxes do not overlap at all, what is the IoU value?

A 1

B 0

C 0.5

D Undefined

No overlap means intersection area is zero, so IoU is 0.

Explain what IoU (Intersection over Union) measures and why it is useful in object detection.

Think about how well predicted boxes match actual objects.

Describe how you would calculate IoU given two bounding boxes.

Focus on areas where boxes overlap and combine.