This coaster rectification worked great because the coaster is a perfect square. Thus, it was easy to pick coordinates that would make it look great.
This poster rectification didn't work as well for a couple of reasons. Firstly, the poster wasn't a perfect square, which made it hard to rectify perfectly. Also, it has curled up corners, which look strange when rectified.
This mosaic didn't work super well - unfortunately there were some kind of alignment issues. I used a ton of different points to align them, but it didn't seem to help.
This mosaic is actually quite nice, and the linear blending worked okay. Unfortunately, it seems that my phone changed the exposure slightly so the two photos have different color temperatures and a unfortunately clear border.
This mosaic's alignment worked quite well due to the large number of right angles available. Unfortunately, there were some strange artifacts at the edges that I couldn't diagnose.
Learning about homographies was by far the coolest part of this project - I thought it was super interesting that it was so easy to transform images with a pair of correspondences.