Welcome to the next Instructable in my Image Relief collection, in which I give 2D images depth by assigning each pixel a height equal to its brightness. This time, the relief was assembled from a series of full color cross sections, printed to 16 layers of acrylic using a flatbed UV printer. Many thanks to Local Language, an art, design, and fabrication studio in Oakland, who donated the use of the printer and material costs.
Imagine each pixel in an image as a rectangular column, with a height equal to its intensity. A dark blue pixel would have a short height, while a bright orange pixel would be relatively tall.
Luckily, it is not necessarily to model this three dimensional relief in order to find its cross sections. Think of the first horizontal cross section, at the base of the relief (0% intensity). This cross section would include the entire rectangular breadth of the relief, and therefore, every pixel in the image.
Now, imagine the next cross section up, a little bit higher, 1/16th of an inch up. Any pixel with intensity below 6.25% would not be included in this cross section, but all the pixels above this intensity would be. In this way, more and more pixels are filtered out of each cross section.
At the last cross section, only pixels with an intensity of at least 93.75% are included.
I wrote software to accomplish this filtering. At every cross section, any pixel below the intensity of the current cross section was replaced with white. For this to work correctly, the source image could not have any pure white pixels. I adjusted the image’s curves in Photoshop to make sure of this.