As a contingency, I had designed and 3D printed a Picavet suspension for lofting my Ricoh Theta Z1 panoramic camera with the kite. From prior experience, I knew that this camera did not handle the extreme cold very well, particularly if it was using its internal battery. To this end, I designed a custom external battery pack around a Molicel INR-18650-M35A battery, which is rated for operation down to −40°C. This pack includes a battery cell protection circuit, a 5 V output for powering the camera, a direct battery voltage output for powering an external heater, and a flex PCB heater with control circuit wrapped around the battery cell with polyimide tape to heat it to around −10°C; the pack was also specifically designed to mount to the above mentioned Picavet suspension. Using a very similar design to the battery cell heater, I also designed a flex PCB heater for the Theta Z1 camera, which was intended to slip in between the camera body and the silicone sleeve I purchased to help insulate it.² Unfortunately, I forgot to pack the camera heater, along with an adapter to power it and the camera from a wall outlet for extended timelapse shooting; since I wanted to power the heater in addition to the camera, I did not included a USB port on the battery pack and instead included a USB Type C connector as part of the wiring loom for the heater, further complicating this oversight. Fortunately, a colleague on station had a USB cable I could cut apart and solder to the output connector pins on the battery pack,³ and the camera ended up working fine with just the insulating sleeve and external power from the battery pack.

The first time I had an opportunity to fly the camera, I thought I had misplaced the carabiner I had to attach the camera’s safety lanyard to the Picavet suspension and ended up lofting the camera without it.⁴ After flying the camera a bit—and just as I was beginning to reel the kite in because I thought I was pushing my luck without the safety lanyard—the camera wiggled itself loose from the Picavet suspension’s tripod mount screw and fell, but it managed to survive the fall without damage to the optics, suffering just cosmetic damage.⁵ After this, I added lock washers and always used the safety lanyard, wrapping it around the mounting screw such that the lanyard would tighten if the camera started to come loose. While the camera survived, it turns out that it had turned off before I even got it into the air, which was particularly unfortunate as there were clear skies and near-perfect weather; for future flights, I turned on the camera’s Wi-Fi⁶ to allow me to externally monitor the camera while flying it to make sure it was still on.⁷

I flew the camera two additional times, with the second flight yielding the vast majority of the photos. For the second flight, I was able to launch the camera near the Dark Sector Laboratory (DSL) and then walk the kite and camera over to the Martin A. Pomerantz Observatory (MAPO) building, IceCube Upgrade drill camp, the IceCube Laboratory building, and then back to DSL, although the weather was a bit cloudy.

For the third and final flight, it was a bit too windy for the kite. It was pretty much impossible to walk the kite upwind without it becoming unstable, and I wasn’t able to get in quite the position I wanted for photographing the South Pole Telescope, but it still yielded a different perspective than the previous flight.

Since the images were taken with a full 360° camera, here are some panoramas.

I’ve uploaded the design files for the Picavet suspension, the battery pack, and the flex heater for the Theta Z1. Some of the images in this blog post were edited to remove the kite and its shadow, string, and operator.

1. I also had issues with reliably setting the focus, so the Raspberry Pi Camera Module 3, which has autofocus, probably would have been a better choice. The camera was also heavier than I would have liked.  ↩

2. I went as far as purchasing a broken camera on eBay to take apart to see if I could integrate a heater directly into the camera, but I couldn’t figure out a good way to power it.  ↩

3. And also short the data lines together per the USB Battery Charging specification to tell the camera it could draw sufficient current. The backup was to use a rechargable hand warmer with USB output, but this would have been heavier and more difficult to mount to the Picavet suspension.  ↩

4. The carabiner turned out to be in my pocket where I thought it was all along.  ↩

5. The plastic rings around the lenses popped off from the impact.  ↩

6. All flights were while none of the telescopes were observing, since they’re sensitive to radio-frequency interference.  ↩

7. Anecdotally, keeping the Wi-Fi enabled on the camera seemed to help prevent it from turning off in the cold, but I did not thoroughly test this.  ↩

The development of the projection was motivated as a method to store spherical panoramic images, for potential use as a new format for the Pannellum panorama viewer. Since GPU texture limits are defined in terms of square textures, a square projection is ideal for such a use, and a quincuncial arrangement will in general have lower distortion than something like a cylindrical projection, since the sphere is cut in more places. A quincuncial arrangement is also seamlessly tileable, which can help to avoid sampling issues at the image edges. Additionally, to avoid wasting pixels due to varying levels of spatial detail, an equal-area projection is preferred, eliminating the Peirce quincuncial projection from contention, since it is a conformal projection.² For existing projections, this left the Collignon quincuncial projection and the Gringorten projection. However, the Gringorten projection does not have closed-form solutions, which prevents its use in a GPU shader. This left just the Collignon quincuncial projection, but it has significant angular distortion and cusps, which will increase visual artifacts in the projected panorama view and will likely decrease the effectiveness of lossy image compression, e.g., JPEG compression. Thus, the goal was to develop a new projection that had relatively low angular distortion like the Gringorten projection but had closed-form solutions, allowing for a GPU shader implementation.

After going through many, many pages of scratch paper, I developed the new projection described in the paper, which met the design goals. It has closed-form solutions and has comparable—although slightly higher—average angular distortion to that of the Gringorten projection. However, it has lower maximum angular distortion and has only almost-imperceptible cusps. As it does not have a large, arguably-unsightly cusp along the equator like the Gringorten projection, it is probably a better projection even for cartographic purposes, where the lack of closed-form solutions does not present an issue. A comparison of the new projection with the Collignon quincuncial projection and the Gringorten projection is shown below.

The paper’s supplementary information contains all the code necessary to reproduce the paper’s figures, including a Python implementation of the projection and a D3.js implementation. Before including the projection in Pannellum, a detailed comparison of the new projection to existing cube-based equal-area and near-equal-area projections needs to be completed.

1. Gringorten, Irving I. “A square equal-area map of the world.” Journal of Applied Meteorology and Climatology 11, no. 5 (1972): 763–767.  ↩

2. A projection cannot be simultaneously conformal (angle preserving) and equal area.  ↩

1. Roll was already supported in the equirectangular renderer to handle Ricoh Theta S images.  ↩