Public Lab Research note


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Return to Planet LEAFFEST

by cfastie |

Above: Dramatic differences in the surface of Planet LEAFFEST have been documented by repeat flyby missions four days apart. The second mission reached a greater altitude above the planet surface making it appear that topographic relief has been reduced. That's just an illusion, but the change in color actually happened. It was also noon instead of late afternoon, but you get the idea -- fall is here.

Peak color is happening NOW in Vermont. During the weekend the forecast was for rain every day this week, but we got a reprieve on Thursday and I abandoned the office for some aerial leaf peeping. A morning return to the nearby Planet LEAFFEST employed the Fled to lift the Saturn V Rig for an 85 minute flight. The wind was in the same direction as on Sunday's flight, but didn't get much over 10 mph so the Fled was in its element.

SaturnV-674-9.jpg
The Saturn V Rig with S100 under the Fled kite.

I tried a new mode on the SkyShield autoKAP controller. I wanted to zoom in the lens to get more detail in each photo, so I used a mode designed for a lens that is not as wide as the S100. The S100 has a lens equivalent to a 24 mm focal length, and I used a mode designed for a lens of 28 mm. But I zoomed the lens in too far and it was at the equivalent of 39 mm (I didn't know that until later because PowerShots don't display the focal length and I was just guessing). So each photo was not covering as much territory as it should have. The field of view was only about 50° horizontally, and it should have been at least 65° to get enough overlap between photos so they would stitch together. The SkyShield autoKAP controller instructed the servos to tilt and pan too far each time, because it didn't know that the person who zoomed the lens was just guessing.

PetriSat-672-62.jpg
A photo taken right after this guy set the zoom and the mode so that it would be impossible to stitch most of the photos together. Punishment should be firm but account for time served.

I was able to stitch a few of the photos together, but not an entire routine covering 360°. I probably would have done better had the wind been more steady. The Fled flew well, but the wind wanted it to wander from side to side too much. The mode I used takes 35 photos before it repeats the routine, and that takes about a minute and 45 seconds during which the camera should not wander much. So it was the wrong flight to do a bad job trying something new. The image below was stitched in MS ICE from 14 photos.

Petri401_14o16PanoPS.jpg
A stitched panorama from 14 photos taken with an equivalent focal length of 39 mm. This is about as good as I could do with the photos from that part of the flight.

Fortunately I knew I was doing an experiment and after 30 minutes I pulled the kite down and changed the mode and the focal length to a tried and true pair. I also wanted to check the SkyShield batteries because they had already been on a 75 minute flight on Sunday. So I was also experimenting with battery longevity. The batteries were still driving everything, so I sent the rig back up for another 50 minutes.

The SkyShield batteries only lasted for 25 more minutes. After then, the camera kept taking photos, but the rig pointed erratically and most of the photos are of sky (for some reason the tilt servo didn't tilt downwards very often when the batteries were dying). So that set of four AAA alkaline batteries drove the Saturn V Rig for two hours and 20 minutes before they stopped providing adequate juice. Before the batteries failed, the rig captured the 20 photos that are stitched together into the little planet in the lead image. This is the only full set of photos that I could get to stitch because the rig was not staying in the same place even for the 75 seconds it took the routine to complete. So it is not surprising that stitching photos from the first part of the flight was difficult. The little planet image could also be displayed as a spherical panorama (viewed from inside the sphere), but Photosynth won't let me upload panoramas these days. Don't know why.

Flight notes:

Camera:

  • Model: PowerShot S100
  • ISO: 80
  • Shutter speed: 1/800 second (Tv)
  • Focus: manual on infinity
  • Focal length: 39mm (eq.) for first 30 minutes, 24mm (eq.) for next 50 minutes
  • GPS: on

SkyShield:

  • Version: 2.4 (3-switch DIP)
  • Sketch: version 2.08sfm (beta)
  • Mode: Mode 2 (for 28mm lens, 35 photos/cycle) for first 30 minutes, Mode 0 (for 24 mm lens, 25 photos/cycle) for last 50 minutes
  • Customization: The nadir tilt angle was changed from 20 to 11 so the camera was pointed straight down.

Flight:

  • Kite: G Kites Fled
  • Wind: From SSW, 9-12 mph
  • Duration: 85 minutes
  • Photos taken: 1404

Panorama stitching:

  • Software: Microsoft ICE
  • Post processing: No adjustments were made to any photos before stitching. Panoramas exported from ICE were modified in Photoshop.


kite-mapping vermont kite leaffest grassrootsmappingforum northeast saturnv skyshield half-spherical leaffest2015 littleplanet gmf-9

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