Project 6 part A, Mosaics
Rectified Images
I rectified two images so that the main rectangle-like feature on each will show flat as a rectangle. I use similiar methology to what I wrote for the mosiacs (described below)
picture in McCone Hall original
The Organic Coop A frame original picture
Picture in McCone Hall Rectified to square
Organic Coop A frame rectified to rectangle (not entirely perfect)
Methodology
Below are pictures of three Mosiacs
- East Asian Library, Berkeley
- McCone Hall, Berkeley
- Pictures in my church building, Alameda
Corresponding Points
I first plotted corresponding points between images I wanted to blend into mosiacs. For each mosiac I blended two images.
Homography
Next, with the images between each point, I computed a 3x3 homography between them. With this matrix, I can take one of my corresponding points in one image and then apply it to another
Warping
I applied the homography to one of the images using scikit's warp function.
Blending
I tried three blends- adding two images together and having one overlap another (overlap method)
- Adding half of each image in an overlap area between the two images, then adding the remaining non-intersecting parts (Linear Blending
- Masking from the middle of the intersection section to the end of one image to apply Project 3's laplacian stack blend. (Laplacian Blending)
East Asian Library
Original right-hand picture of mosaic
Original left-hand picture of mosaic
Mosiac with Overlap blend
Mosiac with Linear blend
Mosiac with Laplacian blend
McCone Hall
Original right-hand picture of mosaic
Original left-hand picture of mosaic
Mosiac with Overlap blend
Mosiac with Linear blend
Mosiac with Laplacian blend
Church Pictures
Original right-hand picture of mosaic
Original left-hand picture of mosaic
Mosiac with Overlap blend
Mosiac with Linear blend
Mosiac with Laplacian blend
Lessons
- Just a little difference in pixels can make the mosaic image look divided and nastly-cut. We see this in the Picture of East Asian Library. One coordinate point would hit an intersection between two lines in the picture. The corresponding point on the second image would be a few pixels off the intersection, and a few points like these make it so the top of the library does not look completely straight.
- Just naively stiching one image on top of the other does not look good, especially when the homography between the two takes one image and slants it drastically. We see this in the mosiac of McCone Hall. It looks jarring to see one rectangle of a darker color overlayed on top of a signifigantly larger slanted image.
- Gaussian/laplacian blending can only make the intersect between two images seem smoother. It is limited and cannot solve for major color differences between two images. We see this again in the McCone Hall laplacian-blended mosaic