Module 08 Knowledge Check
5 questions. Pass mark 4 out of 5. Answer every question before checking the answer key below, then retry after reading the feedback.
1. Passing xywh boxes to code expecting xyxy…
- A. raises a shape error
- B. produces boxes in the wrong place with no error
- C. is auto-detected
- D. only affects visualisation
2. The IoU threshold that counts as a detection is…
- A. fixed at 0.5 by definition
- B. a choice that changes every reported number
- C. determined by the model
- D. irrelevant to metrics
3. Without non-maximum suppression, a detector…
- A. misses objects
- B. reports one object as several
- C. runs slower
- D. produces lower confidence
4. Lowering the confidence threshold…
- A. raises both precision and recall
- B. raises recall and lowers precision
- C. lowers both
- D. has no effect on either
5. A 30x12 pixel barcode in a 1920px image, resized to 224px, becomes…
- A. still detectable
- B. under 4x2 pixels - destroyed before the model sees it
- C. proportionally larger
- D. unaffected by resizing
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Answer Key and Explanations
Check these only after attempting every question.
1. B - produces boxes in the wrong place with no error
Every format is four numbers, so a mismatch is silent. Convert at the boundary and assert.
2. B - a choice that changes every reported number
mAP at 0.5 and at 0.5:0.95 are different numbers for the same model.
3. B - reports one object as several
Every count and every precision figure derived from the count is then wrong.
4. B - raises recall and lowers precision
This is mechanical and holds for every detector; which end you want follows from error costs.
5. B - under 4x2 pixels - destroyed before the model sees it
The remedy is tiling at native resolution, not a larger backbone.
Practical Check
Apply this module to your own work: complete the module activity for *Object Detection Concepts and Bounding Boxes*, then write one sentence naming what your result shows and one naming what it does not.
Strong Answer Pattern
A strong answer names the task, the evidence used, the check performed, and the remaining limitation. It avoids "proved", "guaranteed", or "always" unless the evidence genuinely supports it.