31 Questions
What is the purpose of using Bag of Words (BOW) in image recognition?
To represent an image using a histogram of visual word occurrences
In feature-based alignment, what is the purpose of computing and applying the best transformation such as affine, translation, or rotation?
To align and match features between two images
What technique is used to address getting a set of incorrect matches (outliers) in feature-based alignment?
Random Sample Consensus (RANSAC)
Why is it important to loop until happy in feature-based alignment?
To continuously improve the matching and alignment results
What is the main task when using Harris, SIFT, etc. in building panoramas?
Detecting and describing features in both images
What role does scientific computing play in object recognition and image processing?
It provides computational methods for analyzing and processing images
What is the purpose of the RANSAC algorithm?
To iteratively refine a model by selecting the best subset of inliers
What does the 'N' represent in RANSAC?
Number of iterations to find the best model
How is the initial number of points 's' chosen in RANSAC?
It is typically the minimum number needed to fit the model
What is the role of the distance threshold 'T' in RANSAC?
To select points within error bounds of the model
What does RANSAC do after obtaining a consensus set of inliers?
It terminates and returns the model
What is the adaptive procedure in RANSAC used for?
To dynamically adjust parameters during model fitting
What does 'e' represent in the adaptive procedure of RANSAC?
Error bound for selecting points within a consensus set
How is the distance threshold 'T' chosen in RANSAC?
'T' is chosen to ensure a high probability for inliers
What does 's' represent in RANSAC?
Initial number of points needed to fit the model
What is the main purpose of repeating steps 1-3 in RANSAC?
To ensure that the best model is found with high confidence
What was one of Lowe's goals in developing SIFT?
To create an interest operator invariant to scale and rotation
Which step in the SIFT algorithm involves eliminating edges and low contrast regions?
Step 4: Eliminate edges and low contrast regions
What is the main purpose of step 6 in the SIFT algorithm?
Keypoint description
What is the adaptive procedure used for in RANSAC?
Choosing the number of points 's'
In feature-based alignment, what does 'T' represent in RANSAC?
The distance threshold
What role does scientific computing play in object recognition and image processing?
It enables efficient computation for feature extraction and matching
What is the purpose of Step 3 in the SIFT algorithm?
To eliminate edges and low contrast regions
What is the difference between Laplacian of Gaussian (LoG) and Difference of Gaussian (DoG) in the SIFT algorithm?
LoG is computationally expensive, while DoG is fast and efficient
What is the main purpose of Step 4 in the SIFT algorithm?
To eliminate edges and low contrast regions
What is the role of orientation assignment in the SIFT algorithm?
To assign orientation to keypoints
How does Step 5 in the SIFT algorithm contribute to making keypoints invariant to variations such as changes in viewpoint and illumination?
By rotating the window to standard orientation
What is the purpose of creating a histogram of local gradient directions at selected scale in Step 5 of the SIFT algorithm?
To assign orientation to keypoints
How does Step 6 in the SIFT algorithm contribute to making keypoints invariant to changes in viewpoint and illumination?
By normalizing the rotation and scale
What is the reason behind breaking the 16x16 window into sixteen 4x4 windows in Step 6 of the SIFT algorithm?
To compute a descriptor for the local image region
What is the main purpose of rejecting points with bad contrast in Step 4 of the SIFT algorithm?
To generate keypoints with sufficient contrast and distinctiveness
Test your understanding of building panoramas, feature alignment, object recognition, and image recognition using Bag of Words (BOW) in computer vision. This quiz is based on the lecture by Dr. Dina Khattab from the Scientific Computing Department.
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