3D illusion rough sketch

Been seen a lot of 3d illusion art works online,and am like there is something about our eyes I don't really get, I guess I would do some reading on that. So today I also decided to come up with different kind of 3d illusion without any already done reference, so I started off with taking pictures of objects placing them on a flat surface some resting on the wall, to have the perfect image of where the shadows are falling and the light areas, after few trials I was able to get the magic behind some 3d illusion. Pictures would be uploaded later on. Thanks for visting and reading