I'd completely forgotten this. The image is made up of three "wireframes" of the 3D model produced by running a "shape from shading" computer program over an image of one of my paintings. Note that parts of the thick wireframe on top have been subtracted out.
I like the soft, hatched shading that's most dense at the top left, like shadow on the backside of a hill.
This picture comes out of the shape from shading experiments I did, where I ran an image of one of my paintings through a program that turned it into a 3D model.
To get the picture here, I took the "wireframe" rendered from the model by a 3D program and rotated eight copies of it around an axis.
The "wire" is laid out in a grid that describes the surface of the 3D model. Wireframes remind me of the metal grids used to reinforce poured concrete, or rolls of fencing. I like them because you can see through them but still see their form, like a friendly ghost.
You can pick out the individual 3D models here at the sides, with their right-angle, deep-dish pizza corners.
I wasted a huge amount of time before I figured out it was the mutability of digital pictures, not the pictures themselves, that really impressed me -- the idea that an image is (abstract) data that can be massaged in an infinite number of ways, and shift from 2D to 3D representation and back again.
Shape from shading (SFS) is a software technique that builds a 3D model from the shading in an image; it was used (early on) to create 3D "elevation maps" from photos taken by space probes sent to Mars, etc. I used crude SFS programs I found on the web to translate some paintings to elevation maps.
The green picture up top is of a 1 by 4 foot section of a failed painting.
I took its right end and inverted it (swapped light for dark) for the top half of the black & white picture just above. Then I scanned that image with a SFS program to produce the elevation map used to build the 3D model at the bottom of the picture.
Note how the model demonstrates SFS's inability to tell shadow from depth: darker just means "lower" and lighter "higher." Newer space probes use more complex hardware and software to get accurate elevations. But then I was scanning pictures, not 3D reality.
Also note that once you have the 3D model, you can feed it to a "rapid prototyping" machine that can carve or "print" a solid 3D sculpture shaped like the model.
That arc -- from solid illusionistic painting -to- digital elevation map -to- solid form -- felt like something really deep to me. It's too bad I couldn't find a way to communicate the feeling.