ValueError: Sample larger than population or is negative about apap-image-stitching

[EadCat]

I guess it is because the number of matching points from the SIFT is less than the default random sampling value=6.

A small number of matching points may be extracted in the following situations (Challenging situations):

1. If there's little overlapping region between source & destination.
2. If repetitive patterns (such as bricks) appear in the image.
3. If input images are not good quality (exposure change, low-resolution, severe distortions).
4. User parameter setting failure (such as resize: size is too small)

Finally, If my answer is wrong, please write an additional issue!

good luck.