iStar Night Shots with HDR

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3DForensics
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iStar Night Shots with HDR

Post by 3DForensics » Fri May 23, 2014 4:20 am

Ran a few more tests this evening with the iStar camera and night time HDR shots. I will let the photos speak for themselves. The area was of my backyard and the first image shows what it looks like to an iPhone 5S. This is a fairly accurate representation in terms of the contrast and lighting.
iPhoneShot.jpg
This next shot is with the iStar set at ISO 200 and auto HDR
ISO200Night.jpg
This shot is with the iStar set at ISO800 and auto HDR
ISO800Night.jpg
This shot is with the iStar set at ISO1600 and auto HDR
ISO1600Night.jpg
Total time on the Auto setting was about 5 minutes or so (I didn't actually time it). However, the additional time for the added exposures is well worth the wait. I can see some great benefit for this type of camera in both indoor and outdoor crime scenes or even fire/disaster areas which may be void of any artificial lighting.

Cheers,

Eugene
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Re: iStar Night Shots with HDR

Post by colhum1 » Fri May 23, 2014 7:35 am

Thanks for sharing Eugene,
Having used my iSTAR in anger at many night scenes, my preferred setting is ISO 1600.
I only get one visit at any scene so I also take images on single shot, x3 and Auto.
The time it takes the unit on single and x3 is so quick it would be silly not too. We always have emergency lighting in some shape or form at the scene.
My opinion, from hundreds of images taken with my Canon and iSTAR, is that the iSTAR captures the whole 'atmosphere' of a scene and not a single view, as we can see of your backyard.

Well done, great results they would compliment/ colour scans nicely.

Colin
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Re: iStar Night Shots with HDR

Post by NTocher » Fri May 23, 2014 9:17 am

Eugene,
Thanks for sharing those tests. It's always great to hear and see the results from users.
I am pleased that iSTAR has really brought the details in the shadows out.
Auto HDR does a lot of scene analysis, and in the dark it has to do a lot more which is why it can take 3 or 4 minutes in your example. The more light, the faster it will capture.
HDR 3 does not do the same in depth analysis and therefore produces a quicker capture, Auto covers the 27 Ev range, HDR 3 covers around 6 Ev.

Thanks
Neil.

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Re: iStar Night Shots with HDR

Post by jedfrechette » Fri May 23, 2014 4:27 pm

NTocher wrote:Auto covers the 27 Ev range, HDR 3 covers around 6 Ev.
I think all of the examples I've seen have been tone-mapped but can the iStar deliver a raw image with the full 27 EV range in a format like .hdr or .exr? I'm also a little surprised that HDR 3 only covers 6 EV, that's only about half the dynamic range of a single shot with a DSLR.
Jed

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Re: iStar Night Shots with HDR

Post by NTocher » Fri May 23, 2014 6:30 pm

Question: can the iStar deliver a raw image with the full 27 EV range in a format like .hdr or .exr?
Answer: Yes, but to clarify - if iSTAR captures 9 exposures using HDR Auto, the ev RANGE spreads to 27 EV (9 exposures with 3 EV separation between exposures). So that is different from capturing a total of 27 exposures, each with a single EV separation.

Question: I'm also a little surprised that HDR 3 only covers 6 EV, that's only about half the dynamic range of a single shot with a DSLR.
Answer: The difference lies in the clarification between the terms "dynamic range" and "EV separation". Yes, you are correct in that the latest DSLR's have sensors with a "dynamic range" of 12 EV or sometimes even more. For example the Nikon D7100 has a "dynamic range" of approx 9.5 EV. (http://www.dpreview.com/reviews/nikon-d7100/14). The sensors on iSTAR have a "dynamic range" of about 10.5 EV.

But I was referring to the "EV separation" between the exposures. So for example, in HDR 3 mode iSTAR captures 3 exposures with 2 EV separation between them, i.e. 1/60th, 1/250th and 1/500th sec. Some eagle eyed readers may do a quick sum here and say "hang on - that's only 5 EV!" However, we actually use shutter speeds in decimal notation but round up or down to fractions for standard photographic notation. So in this example, we could have captured at 1/45th, 1/250th and 1/750th, i.e. 6 EV separation but we write to EXIF as 1/60th, 1250th and 1/500th.

There's a good article that explains EV separation and dynamic range here: http://www.cambridgeincolour.com/tutori ... -range.htm

Neil.

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Re: iStar Night Shots with HDR

Post by 3DForensics » Fri May 23, 2014 7:34 pm

NTocher wrote:For example the Nikon D7100 has a "dynamic range" of approx 9.5 EV.
Good information Neil. I happen to have a D7100. Now I have more to investigate...

Eugene

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Re: iStar Night Shots with HDR

Post by jedfrechette » Fri May 23, 2014 8:35 pm

Ah I get it, when you're quoting 6 EV dynamic range you're not including the additional range provided by the camera's sensor. So the the actual dynamic range of HDR 3 is more like 15-16 EV and HDR 9 is more like 35-36 EV
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Re: iStar Night Shots with HDR

Post by NTocher » Fri May 23, 2014 9:48 pm

jedfrechette wrote:Ah I get it, when you're quoting 6 EV dynamic range you're not including the additional range provided by the camera's sensor. So the the actual dynamic range of HDR 3 is more like 15-16 EV and HDR 9 is more like 35-36 EV
Yes, you are right.
Sorry if my original post was a little unclear. In the office we mostly talk about the spread of EV and ignore the actual capability of the sensor. So in short, on Auto the iSTAR has a huge EV range, much more than most camera systems, all synced, all processed automatically.

Thanks again,
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Re: iStar Night Shots with HDR

Post by 3DForensics » Tue May 27, 2014 4:23 am

So, another test this evening for which I think brings about a lot of strengths of the iStar. I am really liking what this unit can do in the dark with HDR. So, here are some images to show you the difference between the Focus 3D in low light conditions.

First, here is what the FARO scanner was able to produce in low light conditions. there is a street lamp that illuminates part of the yard but it makes for a lot of contrast with the shadows.
ScannerPanoramaSmall.jpg
Here is what the iStar was able to capture using ISO at 1600 and Auto HDR.
iStarPanorama.jpg
This is what the Focus data looks like in 3D.
ScannerColorSmall.jpg
Finally, the recolored scan using the HDR image from the iStar.
HDR RecolouredSmall.jpg
I can see how the iStar could be applied to crime and accident scenes, but just as well to caves, tunnels, manufacturing facilities or anywhere low light causes issues.

Cheers,

Eugene
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Re: iStar Night Shots with HDR

Post by NTocher » Tue May 27, 2014 7:32 am

Nice examples and test Eugene. Thanks for sharing.
Neil.

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