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Module 4 — Object detection

Module 4 quiz & review

25 interactive multiple-choice questions on detection theory, training, metrics, and deployment with lesson review links.

~55 min read + exercises

Module 4 quiz and review

Before we begin

Detection has more moving parts than classification — take your time. Same approach as other modules:

  1. Read each question fully.
  2. Commit to an answer before clicking.
  3. Use wrong-answer links to re-read weak topics.
  4. Aim for at least 20 out of 25 before the project.

Click Try again to reset the whole quiz.


Multiple choice quiz

Interactive quiz

Pick one answer per question. Feedback appears immediately — take your time before clicking.

0 / 25 correct·0 answered
  1. Question 1 of 25

    Object detection output differs from image classification because detection returns:

    Answer options for question 1
  2. Question 2 of 25

    Intersection over Union (IoU) for two boxes measures:

    Answer options for question 2
  3. Question 3 of 25

    Non-maximum suppression (NMS) in object detection:

    Answer options for question 3
  4. Question 4 of 25

    One-stage detectors (e.g. YOLO) differ from two-stage (Faster R-CNN) mainly by:

    Answer options for question 4
  5. Question 5 of 25

    mAP (mean Average Precision) in detection:

    Answer options for question 5
  6. Question 6 of 25

    Feature Pyramid Network (FPN) helps detection by:

    Answer options for question 6
  7. Question 7 of 25

    Anchor boxes in Faster R-CNN are:

    Answer options for question 7
  8. Question 8 of 25

    RetinaNet's focal loss addresses:

    Answer options for question 8
  9. Question 9 of 25

    DETR-style detectors assign predictions to ground truth using:

    Answer options for question 9
  10. Question 10 of 25

    A typical positive anchor assignment during training uses IoU threshold:

    Answer options for question 10
  11. Question 11 of 25

    NMS fails in crowded scenes when:

    Answer options for question 11
  12. Question 12 of 25

    Doubling detector input resolution from 640 to 1280 often:

    Answer options for question 12
  13. Question 13 of 25

    INT8 quantization for edge detectors:

    Answer options for question 13
  14. Question 14 of 25

    AP@0.5 vs AP@0.75 differs in that AP@0.75:

    Answer options for question 14
  15. Question 15 of 25

    Two-stage detectors often have lower false positives on cluttered backgrounds because:

    Answer options for question 15
  16. Question 16 of 25

    A bounding box stored as (x_center, y_center, width, height) normalized to [0,1] is common because:

    Answer options for question 16
  17. Question 17 of 25

    Small objects are harder to detect primarily because:

    Answer options for question 17
  18. Question 18 of 25

    Exporting a detector to ONNX enables:

    Answer options for question 18
  19. Question 19 of 25

    Lowering the score threshold at inference typically:

    Answer options for question 19
  20. Question 20 of 25

    When comparing two detectors, reporting only AP@0.5 might:

    Answer options for question 20
  21. Question 21 of 25

    In torchvision Faster R-CNN, label 0 in `targets["labels"]` means:

    Answer options for question 21
  22. Question 22 of 25

    When calling `model(images, targets)` in training mode, Faster R-CNN returns:

    Answer options for question 22
  23. Question 23 of 25

    RoI Align improves on RoI Pool because it:

    Answer options for question 23
  24. Question 24 of 25

    An empty `boxes` tensor with shape (0, 4) in a target dict is:

    Answer options for question 24
  25. Question 25 of 25

    Placing NMS on CPU while the model runs on GPU often happens because:

    Answer options for question 25

After the quiz — checklist before coding

  • I can convert between xyxy, xywh, and cxcywh.
  • I know why label 0 is background in torchvision detection.
  • I can explain RPN vs RoI head in Faster R-CNN.
  • I can describe what NMS fixes and when it fails.
  • I know the difference between AP@0.5 and COCO mAP.

What's next

Project: train and evaluate an object detector