Public Lab Research note


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360° views of the Bristol landfill

by cfastie |

Above: Stereographic projection of a spherical panorama stitched from 21 photos taken by a PowerShot S100 lofted by a Fled kite over the landfill in Bristol, VT.

The orthophoto image of the Bristol landfill was stitched from some of the nadir photos taken during a 50 minute kite flight. The Saturn V Rig was panning and tilting the camera so that the 25 photos taken every 80 seconds covered most of the viewsphere except for the zenith. About 40 complete pan/tilt cycles happened during the flight, and the 25 photos from each of these have the potential to stitch into a (mostly) spherical panorama.

Some of the photo sets do not stitch well because I was walking the kite to a new position at that time or because the wind moved the kite and rig too much. It's so easy to stitch photos in Microsoft ICE that I tried 30 different photo sets (25 photos each) to find the two used to make the spherical panoramas here.

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Above: Landing the Saturn V Rig. This would look more like a kite flying photo had it included the line spool in my right hand.

None of my stitching attempts included all 25 photos in the completed panorama. That's because the sky was too clear that day. The top row of nine photos includes mostly sky, and when they are pure blue, ICE can't figure out how to stitch them together. The set I used below included 19 of the 25 photos and only a few of the top row of sky. Of the 30 sets I tried, my notes indicate that four of them were "good" or "OK." That is a typical result for a successful flight.

Although there was a lot of sky missing in the "good" panoramas, that was easy to fix. ICE has an "Image completion" feature which fills in any gaps using an algorithm which analyzes the photos surrounding the gaps. So it fills in missing sky with the color from the adjacent sky. I then neatened this up in Photoshop which was also used to clean up a few stitching errors where the horizon had been subjected to some geologically unwarranted faulting.

When a set of photos has been successfully stitched, ICE allows you to display the panorama with 10 different projections. The two projections included here are spherical and stereographic. These project the panorama on either the inside of a sphere (spherical) or the outside of the sphere (stereographic). The lead image is the stereographic projection, also known as a "little planet" projection.

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Above: The spherical projection of a panorama stitched from 19 photos. This image has had sky added to make its height exactly one half of its width. That is a requirement for submitting a panorama to 360cities.net for display in their nice spherical viewer.

The best way to view the spherical projection is with a spherical viewer which allows you to mouse your way around as if you were at the center of a spherical display. This reproduces the effect of seeing what the camera saw as it shot the photos from above. Microsoft ICE allows you to upload spherical panoramas directly to photosynth.net which has a good spherical viewer. But that workflow does not allow passing the panorama through Photoshop to clean up stitching errors. Instead, I had ICE export a full resolution flat image of the spherical projection, tidied it up in Photoshop, and then uploaded a jpeg (18944x9472 pixels) to 360cities.net.

The 360cities viewer is very good, but there is lots of clutter on the display. Fortunately, one of the pieces of that clutter is a little "landscape" button (upper right) that you can click to remove the clutter. You can also open the viewer full screen which removes the clutter.


Over the landfill, Bristol, Vermont
Above: A spherical projection of a spherical panorama displayed in a spherical viewer. All derived from 19 aerial photos and many, many lines of code. Thank you, coders.

It's too bad I didn't know more about the Bristol landfill before it closed so we could have before and after views. There is only one more village landfill operating in Vermont, and it plans to close in a couple of years. That is the Salisbury landfill (two miles from my house) but it does not have a handy high school next to it for launching kites. So a windless day and lots of helium might be required.

Here is a note about using the aerial photos to make 3D models of the landfill surface: https://publiclab.org/notes/cfastie/10-23-2016/3d-visualizations-from-aerial-photos-of-a-landfill-video



vermont kite-aerial-photography landfill kap saturnv skyshield half-spherical littleplanet bristol-vt 360 spherical

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