Public Lab Research note

Gowanus Canal Salt Lot Kite Mapping

by eymund | April 30, 2012 14:50 30 Apr 14:50 | #1849 | #1849

I posted some selected pics from Saturday's Salt Lot kite photography exercises. We got a couple of good shots of the new Composting Gowanus site improvements:

It was too windy to use the balloon equipment, so we tested various camera and rig combinations on our 2 kites.

We are hoping to make a full Canal balloon run on the next calm wind free weekend. We will keep you posted.

Technical notes: I used my daughter's 10 megapixel 3 year old Canon SD 880 Powershot.

Safidy Andrianantenaina showed me that switching the camera from Auto Program mode to ISO 800 made a massive difference in the amount of blurry pictures. Will try again at ISO 400 to reduce overexposure on white areas of aerial.

I also found that my daughter's "Hello Kitty" rubberized cloth hair bands works much better than the regular rubber bands, which have a tendency to snap at the wrong moment.

I managed to get the CHDK Camera script program working on my camera, shooting every 10 seconds, which was much better than "Continuous" mode with the rubber band.

Gena used a Canon Powershot 3100 IS the rubber band technique, which made for more blurry shots, but many more pictures to choose from.

3 big technical innovations for the bottle rigs we used:

1 - we taped window foam insulation tape on the inside of the bottle rigs - this makes for a much more stable camera.

2 - we cut a hole in the side of the bottle rig to allow us to just push the "take picture" button with the "ready to hang on kite" camera bottle rig.

This avoids the last minute scramble of of trying to put the camera in bottle rig, while someone else is fighting with the kite.

3 - we developed the concept of a "bird's eye" rig - where the camera is mounted to take pictures at an angle, rather than straight down (traditional aerial photography).

Though useless for mapping, I've found people at community presentations respond better to "bird eye view" picture than to the traditional map aerial photograph.

We will be testing this new camera rig in tandem with our existing mapping rig in our next balloon outing.

There are some samples here of how we use the kite and balloon pictures for community presentations on Gowanus site discussion issues.

Happy flying !


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2012_28_April_Conservancy_2nd_Ave_Compost_Program_Conservancy_Kite_Photo_by_Gena_and_Eymund_IMG_4265.JPG 4.31 MB 2012-04-30 14:50:13 +0000

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Wow, that second image is golden... a perfect shot of the whole lot!

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Excellent air photos! I agree that oblique shots can be really informative. The ISSUU presentation is fantastic. I finally understand what Gowanus is all about.

We are working on some tips for taking mapping photos with the PLOTS IR camera tool, but some of the information applies more generally. One way to keep the shutter speed high is to use shutter speed priority set to 1/800 second if possible. If the camera does not have that feature, CHDK adds it to Canon Powershots. It is described here:

To eliminate burned out highlights on sunny days, most cameras have an exposure compensation setting. Setting that to -2/3 is common for aerial photos on sunny days. It just instructs the camera to figure out the exposure, then reduce it by 2/3 stop. More here:

I like the photo of you paddling up to rescue the kite.


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