Late last night I had some spare time, in which I wanted to model something in AOI because I had not done for such a long time. I started looking on the internet for illusions. one of the frequent occurrences was the illusion of an impossible 3D like triangle with right-angles coming of it so it could not work. You have probably seen there before somewhere.
my first attempt was just a quick mock up. I just picked a corner and decided to make the rest as it appeared, leaving the last corner not touching. Here is what I came up with. (design 1)
It does not look very good, the illusion kinda works 
I made a small animation of the triangle shrinking down to a cube.
To try and improve the Illusion I tried texturing it a bit more to try and show how there were no bent lines.
The grid lines on the ‘L’ side are aligned but the other are not. Trying to fix this did not work so well
Now it is the other way around. and not any better.
Trying to align the camera was tricky, in the end I worked out that it could not be done. The POV (persistence of vision) was making the front end of the triangle seem bigger than the back side and so it would not work anyway.
I closed down the field of view down to 5º, this remove the problem a bit. but there was still the annoying ‘L’ shaped side that should not be there. I tried redesigning my shape. But I did not get anywhere fast.
Looking up ‘impossible triangle’ in google attracted a few image to my attention, they showed how other people had made it. There were cut outs in part of the front edge.
The next time I did my model I made it to scale with correct sided edges. I turned on ‘snap to grid’ to help.
I also redone the texture to look like the grids chopped it up into lots of cubes.
on this there is no ‘L’ side but the effect is lost as with bad alignment.
At this point I made a PME template out of the shape. I thought it could be useful, But although it make perfectly aligned triangles it was difficult to texture. And when rendering with GI the non-joining edge just look apart. Here are the two examples with the floor just out of view below the triangle and above respectively.
I decided not to use the template as I still wanted to give it a grid like look. I went back to my scale model. I made a texture that was used the checker pattern for each different colour, then applied this to the triangle. I did an overnight render as it was getting late so I set the size up to 800*600 and upped the quality lots. This morning I woke up to find this image.
Now I just wanted to refine this to be perfect. there is a small overlap at the top edge and the top square is a mushy grey. The floor seem to be too far away so I move it up a bit.
A small rest render OK’d.
So without further ado here is the final piece.
Click to enlarge 🙂
The scene file is here made with Art Of Illusion 2.3
I made a quick animation of how it works ( a flyby of the object) render with the raster engine.
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