Public Lab Research note

Mobius non-fish eye and small lifter wrapup

by patcoyle | September 07, 2015 00:21 07 Sep 00:21 | #12201 | #12201

What I want to do

Summarize and wrap up the work on Mobius non-fish eye lens conversion, filter mounting approaches and demonstration with small-lift kites, balloons, and quadcopters.

The replacement non-fisheye lenses provide images suitable for mapping. Mounting the filter media in the lens mount instead of directly on the back of the lens provides flexibility in swapping lenses (for both stock visible camera and Public Lab Infragram plant cam).

The video out cable is very useful for changing the focus of the lens by screwing it into the housing while viewing the video image on a TV.

My attempt and results

Continue to explore non-fish-eye lens options for use with Mobius Infragram plant cam and standard visible imagery Mobius.

See prior note: Mobius with IR cut filter at lens housing

and note: Mobius dual rig with non-fish-eye lens

and note: Mobius non-fish-eye lens conversion

and prior note: Small kites for Mobius: Stowaway Delta

and note: yet more: small parafoil kite for Mobius camera

and note: More re: small pocket sled kite for Mobius camera

and note: Preliminary testing of small pocket sled kite for Mobius camera

Alternate ways to mount the IR cut filter

I tried alternate ways to mount the IR cut filter in the lens mount as indicated in the following images and videos. I'm leaning to use of the 9.5mm filters secured inside the opening of rubber washer with a 3/8" hole. The washer is cut to fit the lens mount and the IR filter is secured in the hole with either adhesive or tape. The tape seemed to work well and was less messy to do.


Small balloons

I also tried small balloons, following up on Jeff Warren's suggestions. These 36' diameter (when flat, un-inflated) foil balloons worked pretty well. Reasonable cost at $4.30 each. They don't take much helium to fill. Using two, provides additional lift and redundancy. Can be easily transported while filled. They also held helium pretty well for several days (with a piece of clear Gorilla tape over the fill point).

The following video playlist shows several aspects of this effort. The 18" when flat (~12" when inflated)) ones Jeff thought of initially did not have enough lift.

Small quadcopters

The Parrot AR Drone 2.0 can be considered for lifting a Mobius or two, but I barely tried it.


Issue: The Mobius Actioncam rolling shutter (the camera does not record a complete snapshot of each frame, but scans vertically across the frame), with not all pixels of a frame recorded at the exact same time. As a result, in some images, straight lines are distorted (curved). Usually, enough images aren't badly distorted and are suitable for mapping, but it is a difference compared to our workhorse Canon PowerShot cameras. This is just another tradeoff between the very light Mobius and the other bigger cameras.


Questions and next steps

Explore where Mobius cameras with non-fish eye lenses fit into the tool set and makes sense to use.

Why I'm interested

As before, I'm interested in using the Mobius plant cam and visible unit with non-fish-eye lenses with the filters placed in the lens mount near the sensor for flexibility in changing lenses. These cameras with non-fish-eye lenses make for a compact aerial mapping solution.

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Pat, we are going to be getting samples of Mobius cameras from the factory, preinstalled with 6mm and 8mm lenses. Hoping to be able to sell these through the store, along with unmodified, and just the lenses for people to do their own mods.

I'll post images once we have them in hand.

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Hi, @patcoyle - managed (with some help) to get the web-based lens distortion removal system working, and worked out some rough settings for Mobius cameras. Would love it if you gave it a spin -- we could develop presets for the different Mobius lenses, to make this workflow easier!

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And a more final version of FisheyeGL is up here now!

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