I am trying to create an Auto Crop tool in Houdini for GameDev. I have sequences of stopmotion animated characters. I need to cut off edges that have no Alpha information.

I've made a setup where I feed an image with an Alpha into SOP's out of COPs. Then calculate the area where Alpha is lower than a certain threshold and delete those points. Then compare the pre-cut min,max points to post-cut and fit those values into UV space, to later use in COPs inside the CROP node.

The issue is that the CROP node can not be animated, therefore only the first frame gets Autocropped, and the rest come out cropped exactly the same way.

Example scene attached.

Any help would be much appreciated.