For the pinhole camera model, the mapping from 3D to 2D coordinates is described by a perspective projection(rectilinear projection). However for the image stitching application, perspective projection will bring some problems. Its primary disadvantage is that it can greatly exaggerate perspective as the angle of view increases, leading to objects appearing skewed at the edges of the frame. The input images:
The images are from the link: https://www.cambridgeincolour.com/tutorials/image-projections.htm
I can't figure out the reason that the left port almost doesn't change much but the right port undergoes much change for the the third image. The overlapping part of the second and third images doesn't change a lot.
The scene contains two black lines. The red square indicates the first capturation position and the blue square shows the second capturation position. To match two images, the second image has been warped as the following figure shows. It looks like the same transformation that the hall example undergoes. I don't understand why such transformation is required to match the two images.