This effect was generated in Filter Forge, a Photoshop plugin that allows you to create your own filters.
Renders n-gonal regular pyramids and tunnel effects. A special technique, developed by me and Sphinx, is used for attaining a linear perspective. We achieved this by doing some thorough algebraic analysis of the offset modules.
The polygon effect is due to a snippet by Uberzev.
pyramid polygon primitive perspective tunnel passage wormhole extrusion scaling rescaling distance field linear 3d depth volume