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UltravioletPhotography

Helianthus annuus (Vis, UV, SWIR 1500-1600nm, IRG, 850nm IR, UVIVF)


Andy Perrin

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A classic sunflower. The SWIR is the major contribution here, because many sunflowers have been imaged before on this forum. I made a 530 image panorama to get adequate resolution, and the results look nice. It took all night to stitch the images, and I went through 5 software packages before I found one that didn't get bogged down by the sheer number of images involved. Most stitching programs are geared toward a small number of images with a large number of pixels, rather than the opposite situation, which is what I have with the TriWave!

 

Vis

sunshine Resolve 60mm lens, F8 iso640 0.04" (DB850+S8612 1.75mm)

post-94-0-08876200-1565985521.jpg

 

UV

sunshine Resolve 60mm lens, F8 iso2500 2"

post-94-0-97664100-1565985547.jpg

 

Vis

sunshine Resolve 60mm lens, F8 iso640 0.04" (DB850+S8612 1.75mm)

post-94-0-01227200-1565985535.jpg

 

UV

sunshine Resolve 60mm lens, F8 iso2500 2"

post-94-0-16985600-1565985561.jpg

 

UVIVF

ConvoyS2+ Sony FE 55mm lens, F8 iso1000 30"

post-94-0-71348100-1565985619.jpg

 

IRG

sunshine Resolve 60mm lens, F8 iso400 0.005" (DB850+Tiffen #12)

post-94-0-21393500-1565985721.jpg

 

Near infrared (830-870nm)

sunshine Resolve 60mm lens, F8 iso400 0.05" (DB850+Hoya R72)

post-94-0-84209700-1565985771.jpg

 

SWIR (1500-1600nm)

halogen Thorlabs 50mm achromatic doublet, F10-ish, not sure how to quantify the rest of the exposure info. Thorlabs 1500nm long pass filter.

 

534 image panorama stitched with Panorama Stitcher, a Mac app available in the Mac App Store. This was the program that finally worked after trying Hugin, PTGui, Photoshop CS6, Panoweaver, and Autopano Giga. Autopano Giga's free trial actually worked, but when I went to buy it, I discovered that Kolor, the company that made it, had been bought by GOPro, which then discontinued the product! With no way to unlock the software, I had to find another program.

 

Due to stitching errors near the edges, I was forced to crop this more than I would have liked. The results are still pretty nice, though, and I found that the sunflower (as with other members of the aster family) has a dark center in the SWIR 1500-1600nm band, despite being pretty uniformly white in the 850nm NIR range.

post-94-0-87952800-1565985787.jpg

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Andy,

Nice images. The IRG and UVIVF are my favorites.

I am surprised that Hugin didn't work. Did it crash or couldn't handle the stack?

 

It maybe an odd way to go but I would think based on your SWIR camera an Astrophotography software like Deep Sky Stacker (DSS) or Nebulocity, would be better. You have a web camera resolution with 500 or more images, thats basically what an Astrophotography software is designed to handle. However, I don't know what is best for the Mac. I think DSS is Windows only, but I might be wrong.

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Hugin hung and wouldn’t go past a certain point. I will look into the astrophotography software. I was actually considering looking at what microscopy people do with theirs.
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I did some digging. Interesting that Autopano is based on Auto stick, a University of British Columbia software:

http://www.matthewalunbrown.com/autostitch/autostitch.html

 

However, all the licensed commercial packages are dead. People are trying to patition GoPro to make it open source. But a better bet may be to ask the UBC uderline developers.

 

Also from search of Astro forums the most recommended software was Autopano giga, Hugin and PTGui pro.

Hugin may error if you don't have 40% overlap, lots of ram or lots of storage for the temp files.

 

In the microscopy world we call this tiling. ImagJ plugins is always what I would use. I will have to see now whats out. Its been well over 10 years. Fiji or ImageJ 2.0 may have something. The dedicated slide scanners, that I used that were good had Zeiss zen software, that was custom to the instrument.

 

Yes still seems active for 2Dto 5D sticking. See:

https://imagej.net/Image_Stitching

 

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Yes, I looked into the microscopy side yesterday and found that ImageJ link. I downloaded it but I’m out of town till Tuesday so I won’t have a chance to try it.

 

Hugin probably ran out of RAM. I have 16GB but maybe that was not enough. In my opinion the Autopano software is the best.

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Nice work on the Sunflower, Andy. It's always good to find out how one's gear handles the classic reflected-UV reference flower (UV-dark center bull's-eye and all that).
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  • 5 months later...

Yep, that one is much better. Very good, in fact. "-)

And quite fascinating to me as a sunflower lover.

 

Did you also use Panorama Stitcher for this one?

 

Andy, what is your speculation about the purpose, if any, of having a SWIR-absorbing center disk?

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Yep, this is also Panorama Stitcher, which is both the fastest stitcher and the one that handles small images best, that I've found so far anyway.

 

I have no idea why the central disk is dark, but I will note that in doing SWIR imaging of flowers, it seems to be very common among the Asteraceae but NOT other flowers types. So perhaps it's something about the evolution of the Asteraceae that led to it?

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Usually when I see darkness in SWIR I think at water. It isn't the only substance absorbing there, but water is very common, especially in living organisms.
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Stefano, I did an experiment on here with a different aster species, a coneflower, and I took images over time while it dried up. The color did not change at all, although the water content obviously did. So it isn't water, at least in coneflowers. My money would be on some kind of carbohydrate.

 

https://www.ultravioletphotography.com/content/index.php/topic/3383-experiment-does-drying-a-coneflower-change-its-swir-pattern/page__fromsearch__1

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