CS 194-26 Image Manipulation and Computational Photography

Project 5A : IMAGE WARPING and MOSAICING

Yin Tang, cs194-26-acd



Overview

For this project, we experiment with homographies and then warp overlapping images from different projections to blend them into a paranoma mosaic.

Part 1 Shoot the Pictures

It's hard to go out given the current pandemic situation, so all the pictures are taken from back home or found online.

left
right
rectification image 1
rectification image 2
rectification image 3

Part 2 Recover Homographies

For perspective transformation, there are 8 degrees of freedom, so at least 8 correspondance points are needed for calculating the matrix; if there are more points, then we can use lease squares to solve the overconstrained system of equations. For this part, 30 correspondance points are used for more accuracy.

left points
right points

Part 3 Warp the Images

Using the perspective transformation matrix, we can warp the left image into right image's projection.

warped left
adjusted right

Part 4 Image Rectification

Using the same method to find the perspective transformation matrix, we can warp any planar surfances into front view projection. Here are few examples.

ori img1
rec img1
ori img2
rec img2
ori img3
rec img3

Part 5 Blend the images into a mosaic

When images are registered, we can blend them to form a wider-angle-perspective mosaic picture. First approach I try is simplying adding them together, which creates a wierd picture with high brightness in the middle, then I use a simple mask to weight average the middle part. Using this method will create a line of edges between where images are blended together, and I am going to explore more advanced method later in part B.

simple add
mosaic