3D perspectives on Janwú’s home My mountain goat observations dating back to 2015 fill 3 enormous journals. During that time…2021 | Richard Carstensen | 15 pages of excerpts
The land in 3D: resuscitating stereoscopy
A venerable art It used to be that every forester and field geologist was proficient in stereo-photo interpretation. The digital age has briefly distracted us, but a few cartographers are bringing it back. Evolving stereoscopy—with tools such as flicker glasses and new measuring capabilities—will be way more immersive and powerful.
How-to If you properly size stereo-pairs such as these examples on your computer monitor (about 70 mm across either of those paired images), you can hold a pocket stereoscope to the screen and the landscape will ‘pop up.’ But those lenses typically magnify by 2x, and at that power, on most monitors, you’ll see the pixel-grid, giving a disappointingly grainy view. Phones and tablets, however, (and some higher-res laptop screens) have smaller pixels that don’t show under 2-power blow-up. Magnified stereo airphoto viewing is beautifully suited to the high resolution and rich color on Android and Apple phones and tablets. In fact, it’s the only use that really justifies their ridiculously high pixel density.
Free viewing Okay, so you don’t have a pocket stereoscope at the moment. If you can see the hidden ‘pop-up’ images in those magic-eye 3D picture books, your eyes are capable of fusing these paired images into a stereoscopic model, without the aid of optical devices.. Bring one of the pairs below up on your phone. Rotate it into landscape position to fill your screen. Hold it about a foot away and focus your eyes on something distant, over the top. Slowly drifting back onto the screen, try to relax your gaze, preventing a ‘convergent focus’ on the phone itself. ‘Pull’ the 2 images together. The moment they completely overlap, a terrain model will pop up.
Field use For stereo-viewing, no printed color photos can match the resonance of a backlit aerial on a phone or tablet. In future posts, I’ll share some of the ABCs of creating and using stereograms. For now, I’ll only note that stereo-interpretation has been a key tool in my recent consulting work, thanks largely to phones and tablets. Although slightly less convenient in the field than my little 3D slide viewers (relicts from the days of film photography), I frequently stop for a stereo-orientation during forest and wetland bushwhacks.
3D at home Stereo is handy for post-field processing and review. Back in camp or office, I drop the day’s GPS track, waypoints, and autolinked photopoints onto one of the 2 paired images. Then, habitat-mapping is enhanced by an order of magnitude more spatial information than when tracing polygons over a flat, 2D image.
From 30,000 feet to 3 centimeters Stereo adds information to all scales of imagery, from ultra-high-elevation NASA flights at inch-to-mile scale, to creek-skimming Beaver flights that show individual alder branches, to macro-3D of red mites traversing moss-jungles. Drones can acquire high detail stereo unavailable from traditional aircraft. My first experiments were on Robin Trib, shooting from 150 feet above uplift parkland, with a Ricoh GR pocket camera strapped to a quadcopter and firing in interval mode.
Stereo and drones I shoot almost exclusively video from my drone. But from 4K mp4s, screengrabs are usually fine for inserting into journals and reports. There are 2 interesting ways to create stereopairs from drone video. One is from a flyover with nadir (straight downward-facing) camera. The other is from an oblique camera in sideways-crabbing flight. From either of these video segments, extract your screengrabs just a second or so apart. How long to wait between extractions depends upon flight speed and distance to target. (2023 In addition to video, I now fly preprogrammed missions collecting hundreds of overlapping nadir still images that are processed into orthophotos and terrain models. These images are also great for creating stereopairs)
In this section
Retakes field journals, 2005 season Summarizing the Repeat Photography Project for 2005, Kathy Hocker and I divided our field reports…2005, 2nd ed 2013 | Richard Carstensen & Kathy Hocker | 40 pages
3D landscapes through a stereoscope Stereograms are paired pictures taken from slightly different angles, in order to be seen in…Summer 2000 | Richard Carstensen | 10 pages
I wrote this as an appendix to my report with Kathy Hocker on repeat photography. It reviews trends in a…2013 | Richard Carstensen | 6 pages
I created an early version of this compilation while still living at the Scout camp at Asx’ée, twisted tree (Eagle River),…2020 | Richard Carstensen | 38 pages
Seawalk: Rehabilitating our waterfront. 2013: To evaluate change along the shoreline proposed for a seawalk, I georeferenced a series of…2013: updated 2022 | Richard Carstensen | 22 pages