Bas Relief Light Sculpture

Step 2 Image selection and modification

I fielded a lot of questions about image selection at the Makers Faire, and what follows is the best advice I've been able to come up with.

• use images that have strong directional lighting. You may have more than one source of directional lighting, but very diffuse light is not good. Stronger gradients are better. Camera-mounted flash-photography is bad. Don't pick a simple silhouette, or something front lit. it should be off-angle lighting to emphasize the cognitive dissonance.
• an image that needs very fine detail for its impact makes the carving very tedious - so avoid extreme subtlety in expression if you're doing portraiture. Pick something that will have punch, even if it is very blurry.
• I think it's also good to have an image where both the foreground and background of the image have gradients. If the background is always much brighter or darker than the foreground, then your topography won't be interesting. You'll have a plateau or a simple recess that outlines your figure rather than an dynamic interplay of sculptural shapes. (You can fix this in an image you like by messing around in your image editor.)
• extreme close-ups for portraiture can create interesting and unintuitive topographies where the image jumps out suddenly.
• at a crazy advanced math level, you'll probably start to be able to see the topographical forms that the sculpture will take based on the light patterns. At this point, you'll want to pick cool-looking topographies that create unintuitive images when viewed from the viewing angle. I wish I could do this better. It really taxes my brain, but it's what I'm trying to get better at.

So, with all that in mind, get your image. Draw something, take a photo, or find something. If you're drawing a blank, google image search can help. pick an adjective and do an image search. Use CoolIris to scan your seach quickly for something that catches your eye.

Now that you have your image, adjust it so that it's easy to interpret into your sculptural topography.
Photoshop, the Gimp, or another graphics program can help quickly reduce the image to something carve-able. You'll want a black and white image with a lot of contrast. Some areas should be washed out (entirely white) other areas should be lost in shadow (totally black) you also want some mid-tones. Use "levels" or "curves" to alter the contrast on your image. Then use "cutout," or "posterize," filters to alter the image. This will create discrete lines from the gradients to guide your carving. You can think of them as topographical isobars. Your goal is to make obvious the light/dark gradients in your image so that you can translate them to height/depth gradients in your carving.

note: if you're carving in something other than a pumpkin, (specifically, something like styrofoam) where you don't want to completely cut through the object, and where you don't have a top "skin" that will create dramatically contrasty blacks, you probably don't want to have an image that is too contrasty. You still want a lot of range, but you want smooth gradients that keep detail in the highlights and dark areas. This is because a solid black area will become an flat-topped plateau in your carving that isn't sculpturally as interesting as a rounded hill or a jagged peak. Take a look at what I'm talking about in the maker's faire styrofoam carving below. It still looks like a block of styrofoam because the shadows got cut off. It would look better if it had rounded peaks rather than a chopped plateau.