CS 194-26: Project 6

Karuna Wadhera, CS194-26-abo

[Auto]Stitching Photo Mosaics (Part 1)

This part of the project was very enjoyable because relatively simple code achieved perspective shifts and image stitching that I would have thought required much more elaborate techniques.

When calculation the homography matrix I learned of yet another application of least squares.

It was really wonderful to see how easily you can view an image from an alternate perspective without any additional information.

This project really honed my debugging skills -- I spent hours tracking down what I believe ended up being x and y swaps when computing my inverse transform. Indices are hard -- really hard!

When blending the images together, I was suprised by how well just choosing the maximum element-wise values did to blend (which someone recommended on Piazza). I first tried alpha blending but just choosing the max honestly looked even better!

Rectification


Original
Rectification
Original
Rectification

Mosaic Stitching


Left
Right
Warped Right
Stitched
Top
Bottom
Warped Bottom
Stitched
Top
Bottom
Warped Bottom
Stitched



Feature matching for Autostitching (Part 2)

When I take a step back and look at this project as a whole, it really is quite amazing that we're able to put in image names as input and get a stitched panorama as output. Very cool.

In this part, I also learned what it means to tune parameters :) In other words, how important it is to select the right features. Selecting the epsilon used to decide whether inliers and deciding the number of iterations we'd run RANSAC for definitely affected the types of images I'd get.

It was awesome to learn about ANMS and how you actually go about matching features from one image to another. I was indeed glad not to have to manually pick points.

It was also interesting to learn how to use randomness in an application like this -- running the same thing multiple times can indeed get you slightly different results due to the randomness in RANSAC.

Finding corners!


Original
Black + White
Harris Corners
After Adaptive Non-Maximal Suppression

Mosaic Stitching


Left
Right
Stitched With Auto Feature Picking
Stitched With Manual Feature Picking
Top
Bottom
Stitched With Auto Feature Picking
Stitched With Manual Feature Picking
Top
Bottom
Stitched With Auto Feature Picking
Stitched With Manual Feature Picking