Perspective Transformations

[MentalGear]

Perspectie transformations seems to be available, but not listed at https://imgaug.readthedocs.io/en/latest/source/augmenters.html

[aleju]

Yes, that overview page is very out of date and misses like half of all augmenters...
There will be an updated one upon release of the next version of the library. It is just not merged yet, because the next version also contains some breaking changes.

[marz233]

When I using Perspective Transformation there is some problem:
The polygon after perspective transformation should stay in the image boundary,not like the image show below

Is it a bug exist?
Maybe clipping algorithm like Sutherland-Hodgman or Weiler-Atherton can solve this problem？ :P

[marz233]

emm... I got clip_out_of_image() to solve the problem above
psoi_aug=psoi_aug.clip_out_of_image()

[marz233]

I found clip_out_of_image() can only clip one polygon to another one,the problem is concave polygon after clip might divide into more than one polygon：P
How should I deal with this？

[aleju]

Polygon.clip_out_of_image() returns a list of 0..N polygons, i.e. one input polygon can become multiple polygons after clipping. Isn't that what you want?

[lamhoangtung]

When I using Perspective Transformation there is some problem:
The polygon after perspective transformation should stay in the image boundary,not like the image show below

Is it a bug exist?
Maybe clipping algorithm like Sutherland-Hodgman or Weiler-Atherton can solve this problem？ :P

Check out this PR #452, it's already merged into master. So you just need to:

pip install git+https://github.com/aleju/imgaug

and do this:

iaa.PerspectiveTransform(scale=(0.075, 0.1), fit_output=True, mode='constant', cval=0)