Relief as Light
Sarah Preston
Artwork for ‘Waves‘ (Issue 22)
The Science
Relief as Light is derived from a digital elevation model of a field of meter-scale wind-blown ripples blanketing the lower flank of a cinder cone volcano in southeastern California, USA. Like ocean waves slowed to a crawl, these ripples shift slowly with the wind. These ripples bear remarkable resemblance to the meter-scale ripples found on Mars, despite Earth’s comparatively high gravity and atmospheric density and the terrestrial ripples’ coarse grains. Relief as Light emphasizes variations in topography in unpredictable ways: in some areas, it shows the gentle slopes of the underlying surface; in others, it makes waves of its own.
The Medium
Relief as Light was created with a MATLAB script that breaks the original drone-derived ~300 meter by ~300 meter digital elevation model into 1.5-meter tiles, finds the vertical cross section with maximum relief through each tile, and returns an elevation profile. It then treats the elevation profile like a spectrum. Each third of the spectrum corresponds to a range of wavelengths of visible light and thus to a color. The maximum elevations in each wavelength band are converted to an RGB triplet, and each tile is covered with a square in its corresponding color.
As for the color scheme: It’s algorithmically defined and depends on the topography data, though I did attempt to select a tile size that maximized variation from pixel to pixel. As a geomorphologist, I find myself subject to the whims of elevation data. This is both a source of beauty and a source of endless confusion—in this case, I have no idea why the colors ended up being as bimodally blue and orange as they are!
The Artist
Sarah Preston (she/her) is a geology PhD student and occasional artist based in Los Angeles, California, USA. As a geologist, she studies sand dunes—and rocks that used to be sand dunes—on Earth and Mars. As an artist, she creates data-based visualizations and mathematically inspired crochet pieces. Her artwork has previously been displayed in the solo exhibition bitter water at Rice University’s Sleepy Cyborg gallery.
Copyright statement. This work is published under the CC BY-NC-SA license