CS4670 Project 3 - Panoramas

Kolbeinn Karlsson (kk752) and Pradeep Gopinathan (pbg42)
10/18/12

In this project, we implement a program that takes a series of overlapping images and stitches them together into a panorama.

Part 1: Spherical Warping

This was pretty straight-forward. We just had to convert from spherical coordinates to Euclidian ones and add radial distortion. The change from spherical coordinates was done in the following manner:

$(\hat{x},\hat{y},\hat{z}) = (\sin \theta \cos \phi, \sin \phi, \cos \theta \cos \phi)$

We then normalized the coordinates by projecting them to the z=1 plane:

$x'_n = \frac{\hat{x}}{\hat{z}}$

$y'_n = \frac{\hat{y}}{\hat{z}}$

Finally, we apply radial distortion:

$x'_d = x'_n (1+ \kappa_1 r^2 + \kappa_2 r^4)$
$y'_d = y'_n (1+ \kappa_1 r^2 + \kappa_2 r^4)$

Then we are good to go.

Part 2: Alignment and RANSAC

The base case of translation was quite easier than the homographies. While the math behind the homographies was not too difficult to understand, it was difficult using the package to get it to do exactly what we wanted it to do.

Part 3: Blending images

The images were blended using simple feathering. We the used the alpha channel to keep track of the accumulated weight of each pixel to normalize it in the end.

Results

The test sequence

Unfortunately we didn't get the interactive panorama viewer to work in time for the deadline, so this plane-ol' non-interactive image will have to do.

Our images

Our panorama did not go all to well.

When we ran Panorama on it, all we got was this:

We got the same output from the solution executable, so the problem is presumably not in our code, but in the quality of the images or the feature matcher.

360 Panorama

We also tried making a 360 panorama with the test images supplied and it worked beautifully: