Overview

In this project, I shot and digitized photos, recovered homographies, warped the phots, and blended them into mosiacs using linear blending.

Image Warping - Rectified Images

After shooting and digitizing a set of photos, I tried to figure out a way to recover a homography matrix between two sets of point correspondences. To do this, I take Hp = p' where p = [x, y, 1] and p' = [wx', wy', w] and convert it to Ah = b where h is the 8 variables in H and b = [x', y']. I add more rows to A and b depending on the number of point correspondences we are using to compute a Homography. Then, I use least squares to get the 8 variables in h and convert into a 3x3 H matrix. I then use the inverse of H to warp my images. Shown below, I have "rectified" two images by warping them so that certain planes are frontal-parallel. To do this, I chose a set of points on the original image and warped them to a set of points that I manually set. For the first set of images, I rectified a dining room image so that the purse is in the front view of the picture. For the second set of images, I rectified a lobby image so that the fire alarm box is in the front view of the picture.

Dining Room Image	Rectified Image
Lobby Image	Rectified Image

Blending Images into a Mosaic

For making mosaics, I took my first image and placed it into a bigger black image. I then warped my second image to this bigger black image. To combine this warped image with the bigger image, I tried to use linear blending. I created a mask that fell off linearly from 1 to 0 in the overlap region between the bigger image and my second image. This seemed to do a good job getting rid of some but not all artifacts. The results are shown below for three mosaics. The first is a wall in my apartment's living room. The second is an intersection outside my apartment. The third is the lobby of my parents' house in Saratoga.

Left View Wall	Right View Wall	Wall Mosaic
Left View Intersection	Right View Intersection	Intersection Mosaic
Left View Lobby	Right View Lobby	Lobby Mosaic

What I've Learned

From this project, I learned that image warping and blending can create seamless-looking panoramas. In general, it is cool to see how a mix of processing techniques can create illusions that would potentially fool the average person. I am excited for the next phase of the project, where we do not have to manually click points to create mosaics.