I don't know what/where the bucket is, what/where the sand is, and where the shadows are. The lighting is horrible and could definitely be improved. Plus who's idea was it to have a sand-colored background when you want to find sand pouring in front of it?!?! The disc thing should be black or at least some contrasting color. I'd fix all that first since it's far easier to design an image analysis algorithm if you have a good image to start with.