Mobius non-fish eye lens conversion

This Public Lab note explores alternative non-fish eye lens options for use with Public Lab Mobius Infragram plant cam or standard visible imagery Mobius. The "flat" images are preferred for mapping in MapKnitter or other auto-stitching programs. I'm interested because the Public Lab Kickstarter: Infragram: the Infrared Photography Project back in 2013 had almost 300 people pledge for this option, so there is a good sized set of potential users. I also hear that the unit continues to sell from the PL kit store. However, I don't see many user mapping results.

http://publiclab.org/notes/patcoyle/08-01-2015/mobius-non-fish-eye-lens-conversion

This earlier note presented initial results of using the Mobius on on Parrot AR.Drone 2.0:

http://publiclab.org/notes/patcoyle/11-27-2014/initial-results-pl-mobius-infragram-point-and-shoot-on-parrot-ar-drone-2-0

Thanks, all. I'll try to address these below. Before, I'll add update based on dual camera test flight:

The results are in this Public Lab note: http://publiclab.org/notes/patcoyle/08-03-2015/mobius-dual-rig-with...

Re: How much is the Infrared imaging instrument? This approach relies on the existing camera sensor, filter material, and software to post-process the "false-color" image to deliver NDVI. See extensive information at:

http://publiclab.org/wiki/infragram-point-shoot

People who bought the Plantcam, got a small circular piece piece of the Wratten25 filter media, installed on the back of the standard fish-eye lens. It is available at the Public Lab store for $125 at:

http://store.publiclab.org/collections/diy-infrared-photography/pro...

In my case, rather than reuse it, I changed to a 0.5" square piece placed in the lens mount, directly in front of the sensor. I found mine used on E-Bay or Amazon, but a 3" square piece is available new for $44 plus shipping, from B&H at: http://www.bhphotovideo.com/c/product/503645-REG/Kodak_8424988_3_x_...

If you have the larger piece of filter media, can consider that many of the Canon Point and Shoot models (with better optical characteristics and image quality than the Mobius) have been converted to deliver NDVI with this approach. For the ones with CHDK available, they can run an intervalometer script or be triggered via remote shutter using USB connection, a nice feature for UAV imaging. Numerous examples and instructions are shown on Public Lab and other's sites. This note shows initial results for an A1200 modified with this material:

http://publiclab.org/notes/patcoyle/02-22-2014/initial-ndvi-results...

Re: I'm using with 6 mm lens but quality lens isn't the same than original one. Any know a good quality lens. I don't know the quality characteristics of the inexpensive standard security cameras, but this guy has good reviews in the R/C community and sells expensive conversions and lenses. Dennis, the owner was helpful.

http://ragecams.com/shop/

Re: Why not just keep the fisheye for now and try to flatten the image with post processing and calibration with OpenCV before uploading to MapKnitter? If it works for you great. However, I've tried PTLens and Gimp's tools, but so far find the "flat lens non-fish-eye" approach more to my liking. As Chris Fastie, who was instrumental in developing the Public Lab plant cam, noted, "It’s a great idea to use a more normal lens on the Mobius for mapping. While you can correct for the distortion of the standard wide angle lens, you can never correct for the fact that objects at the edges of each photo will be photographed from an oblique angle, not from above. It also seems that part of the distortion correction procedure is to crop the image, which throws away lots of resolution."

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Comments

Cala August 3, 2015 at 2:52pm

Thank's Patrick for share this information, the Kite remembers me my first aerial photograph aircraft, a Rokkaku ;)

I use two mobius one RGB and the other only IR (modified) to do withe balance I take photos to a white paper on the grass and change settings until paper looks white, the filter is from B&H too. I modified the Mobius to easier attach on the airplane, like this
Patrick Coyle August 3, 2015 at 11:41am

Thanks, all. I'll try to address these below. Before, I'll add update based on dual camera test flight:

The results are in this Public Lab note: http://publiclab.org/notes/patcoyle/08-03-2015/mobius-dual-rig-with...

Re: How much is the Infrared imaging instrument? This approach relies on the existing camera sensor, filter material, and software to post-process the "false-color" image to deliver NDVI. See extensive information at:

http://publiclab.org/wiki/infragram-point-shoot

People who bought the Plantcam, got a small circular piece piece of the Wratten25 filter media, installed on the back of the standard fish-eye lens. It is available at the Public Lab store for $125 at:

http://store.publiclab.org/collections/diy-infrared-photography/pro...

In my case, rather than reuse it, I changed to a 0.5" square piece placed in the lens mount, directly in front of the sensor. I found mine used on E-Bay or Amazon, but a 3" square piece is available new for $44 plus shipping, from B&H at: http://www.bhphotovideo.com/c/product/503645-REG/Kodak_8424988_3_x_...

If you have the larger piece of filter media, can consider that many of the Canon Point and Shoot models (with better optical characteristics and image quality than the Mobius) have been converted to deliver NDVI with this approach. For the ones with CHDK available, they can run an intervalometer script or be triggered via remote shutter using USB connection, a nice feature for UAV imaging. Numerous examples and instructions are shown on Public Lab and other's sites. This note shows initial results for an A1200 modified with this material:

http://publiclab.org/notes/patcoyle/02-22-2014/initial-ndvi-results...

Re: I'm using with 6 mm lens but quality lens isn't the same than original one. Any know a good quality lens. I don't know the quality characteristics of the inexpensive standard security cameras, but this guy has good reviews in the R/C community and sells expensive conversions and lenses. Dennis, the owner was helpful.

http://ragecams.com/shop/

Re: Why not just keep the fisheye for now and try to flatten the image with post processing and calibration with OpenCV before uploading to MapKnitter? If it works for you great. However, I've tried PTLens and Gimp's tools, but so far find the "flat lens non-fish-eye" approach more to my liking. As Chris Fastie, who was instrumental in developing the Public Lab plant cam, noted, "It’s a great idea to use a more normal lens on the Mobius for mapping. While you can correct for the distortion of the standard wide angle lens, you can never correct for the fact that objects at the edges of each photo will be photographed from an oblique angle, not from above. It also seems that part of the distortion correction procedure is to crop the image, which throws away lots of resolution."
Xon Xoff August 3, 2015 at 6:41am

Why not just keep the fisheye for now and try to flatten the image with post processing and calibration with OpenCV before uploading to MapKnitter?

One link for camera calibration...

http://www.aishack.in/tutorials/calibrating-undistorting-with-openc...
Cala August 2, 2015 at 7:09pm

I'm using with 6 mm lens but quality lens isn't the same than original one. Any know a good quality lens.
Laser August 2, 2015 at 6:29pm

How much is the Infrared imaging instrument.

This reply was deleted.