In this project, we'll see how to stitch images together into mosaics. This first part involves image stitching using manually picked point correspondences.
Image stitching involves three steps:
First, let's use warping for a different application, rectification. Rectification means transforming the image so that one of the planes is directly parallel with the image plane. We can perform rectification by (1) picking four points forming a square on the plane of interest, and then (2) warping these points into an actual square, or the points \((0,0), (a,0), (0,a), (a,a)\). Below are some examples. In the first case, we rectify to the right face of the building, and in the second case, we rectify to the face of the building.
Next, let's look at examples of mosaicing. I took these pictures in my home. Unfortunately I couldn't get any nice pictures of scenery due to the quarantine. In each example, we show the two original images, the mosaic with simple average blending, and the mosaic with linear blending.
I enjoyed making mosaics and I am glad that I now have this technique in my toolkit. It was interesting to learn that you actually shouldn't move the camera while taking the panoramic photo. It seems that since most people take pictures of scenery, which is faraway, the parallax effect is less noticable. But during the project, I realized that it matters a lot if you take pictures of nearby things!