The first option is changing the geometrical shape form a block to a pyramid. The block effect gives better results, but if you particularly need a spiky effect on an image, the pyramids do that very well.
The size and depth of your geometrical shapes can be altered too, where the size is the xy axis proportion and the depth is your z axis, the one coming out at you. As a general rule, the more detailed the image, the smaller the size of your blocks or pyramids should be. The depth value is a maximum as how deep each shape becomes is dependant on the Random and Level based depth settings.
Changing the depth setting from Random to Level Based means Photoshop will use the tonal levels in your image or selected layer to choose how the depth of each block, this gives you an effect that is more closely linked to the image you are rendering, and can be especially effective if you have larger defined sections of your image that have dramatically different tones. As with all these filters, try experimenting with the setting and see if you can come up with a result that works.
Choosing the Solid Front Faces tick box means each shape has a flat colour based on an average of the image underneath, if you untick this box, the actual image appear on the shape, this only really works when your depth setting is quite high though. A better option if you are trying to keep the original image recognisable is to lower your pixel size setting. Finally the Mask Incomplete Blocks option when turned on will leave a nice clear edge to the effect and not apply the filter to any blocks that would extend beyond the border of your image, so you get a pleasing central clump of blocks that is much more noticeable when using larger shape sizes.
Don’t dismiss the Extrude filter as a gimmick, it can be a quick and effective way of making a very flat graphic really pop out from the page, or for making a flat background colour become an interesting range of levels and by adjusting your depth and size values and using the Level Based depth setting, you can get results that are quite unique.
[Image via Russ Payne]