Skridlov
Posts: 116
Location: United Kingdom
Registered: 12 Nov 2007
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Different approaches to HDR stitching?
Posted: 12 Feb 2008 at 17:29 GMT
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I'd appreciate opinions on the following.
For what it's worth I'm beginning to get fairly reasonable results in my attempts to produce some panos of local church interiors (peaceful and usually quiet locations in which to practice!)
The nicest lighting conditions in which to do this are also the most difficult due to the huge exposure range. I have been shooting 9 exposures at 0.7 or 1.0 steps, which may not be the most manageable, but seems to be the safest option given my relative incompetence.
As I see it the alternatives for HDR include:
1) Use the PTGUI merge function
2) Merge in Photoshop using its HDR capability.
3) Manually merge in Photoshop using layers/masking.
I have tried 1) a few times using the middle 5 range of the nine exposures, leaving the default settings. This usually gives reasonable results, but often a little underexposed in the shaded areas - the highlights it seems to get right.
I'm not sure how to go about 2) in view of the range of options available. Is it necessary to use identical merging strategies for every set? Can CS2 accomodate 5, 7 or 9 exposures? (Can my PC? for that matter...)
3) Looks time consuming and shares some of the same problems as 2).
No doubt there are few hard and fast rules, but I'd like to hear any comments forum members might have.
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Doug Aurand
Posts: 484
Location: Albuquerque, NM, United States
Registered: 2 Jan 2008
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Re: Different approaches to HDR stitching?
Posted: 12 Feb 2008 at 18:28 GMT
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Skridlov
What I've played with a couple of time is;
1. Batch stitch the sets of source photos that have the same exposure using the same PTGui template. I've done as many as eight or nine sets.
2. Use Photomatix Pro's HDR/Tone Mapping to composite and make adjustments.
3. Don't forget to click "360°" imafge so it with make the edges work.
I've had faily good results using source photos from my Nikon Coolpix 5400/FC-E9 set up.
Doug Aurand
Albuquerque,NM
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Skridlov
Posts: 116
Location: United Kingdom
Registered: 12 Nov 2007
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Re: Different approaches to HDR stitching?
Posted: 12 Feb 2008 at 20:49 GMT
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Doug, thank you for the suggestion.
"Photomatix Pro's HDR/Tone Mapping"
This is new to me. I'll look it up. But I've spent so much on hard- and software recently that I'm pretty reluctant to buy anything else right now.
Particularly as I'm having enough trouble trying to get nadir shots to stitch...
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Doug Aurand
Posts: 484
Location: Albuquerque, NM, United States
Registered: 2 Jan 2008
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Re: Different approaches to HDR stitching?
Posted: 12 Feb 2008 at 22:27 GMT
updated: 12 Feb 2008 at 22:29 GMT
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Skridlov
You could follow the same steps and end up compositing the HDR/Tone Mapped image with Adobe Photoshop's HDR function, but I don't know if they have a specific function to make sure the the right and left side of the equirectangular projection will match.
There's a nice article in Popular Photo magazine about HDR with both Photomatix and the HDR function in Photoshop at www.popphoto.com/howto/3038/how-to-create-high-dy...
You can download a trial version of Photomatix and its only US$99 for the stand alone program and there is a Plug-In for CS2/CS3 for US$69, it doesn't offer the "Exposure Blending" function as well as the HDR/Tone Mapping of the stand-alone program.
If you're using a camera/lens combo that leaves "black" around the image like a Nikon FC-E9, Sigma 4.5mm or Sigma 8mm, you can't composite with Photomatix before stitching because it blends the "black" too.
Sorry, I've never played with the Photoshop HDR function so I can't make a suggestion for the workflow. But if you're using a lens that fills the image frame, I would suggest compositing the sets of source images first in Photoshop. Then stitch the resulting images together.
Good luck
Doug Aurand
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John Houghton
Posts: 2133
Location: Hitchin, United Kingdom
Registered: 17 Jan 2005
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Re: Different approaches to HDR stitching?
Posted: 13 Feb 2008 at 7:58 GMT
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You might try the Enfuse blender (free). This is not an HDR program, but it produces a similar end result that you are after and is very easy to use. You can blend the sets of images before stitching using a batch process, or you can stitch the sets separately and blend afterwards.
John
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Robert Piontek
Posts: 97
Location: Germany
Registered: 26 Jul 2007
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Re: Different approaches to HDR stitching?
Posted: 13 Feb 2008 at 8:50 GMT
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In the beginning I fought hard to get HDR to work. The big problem I tended to have was the moving objects, particularly trees and leaves, do not align and blend well with HDR. I tried many different programs to do the HDR.
So, I do the exposure blending by hand in PS. At first it wasn't so easy, but it get easier as you go. While the tress and leaves still do not line up, it's much less noticeable. I should add that I do not want the HDR look. Typically all I really want to do is decrease the sky brightness.
I think using 9 brackets is over doing it. Hard drive space fills up, camera wears out, takes too much time. I'd bracket at +2, 0, and -2, and go antother 2 stops only if you need to. If you working in a dark church, then set the +2 exposure to be well exposed for the dark areas, and then see if the -2 exposure will be enough to keep the windows from blowing out.
Also try enfuse. You don't have to learn anything to use it, and it seems to give good results. Plus it's free!
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bigwade
Posts: 250
Location: Netherlands
Registered: 19 Oct 2005
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Re: Different approaches to HDR stitching?
Posted: 13 Feb 2008 at 13:49 GMT
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John Houghton said: . You can blend the sets of images before stitching using a batch process, or you can stitch the sets separately and blend afterwards. John
What is better, enfuse images (sig8 with black corners) before or enfuse the Equis/PTGui output ?
Have Fun
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John Houghton
Posts: 2133
Location: Hitchin, United Kingdom
Registered: 17 Jan 2005
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Re: Different approaches to HDR stitching?
Posted: 13 Feb 2008 at 14:52 GMT
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It's hard to say which is best. I've only done one comparative test and there was nothing to choose between the two final results. Last week I did 3 stitches and opted for enfusing before stitching. Batching the input images (using a .bat file by Eik Krause) seemed the easier option, with a straightforward single stitching run. Your mention of black corners prompted me to check whether the corners should be masked. (It didn't occur to me to do this last week). I did a quick test just now and confirmed that it does indeed make a difference and is recommended. A mask can be conveniently applied via an action when converting from RAW with ACR.
John
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Doug Aurand
Posts: 484
Location: Albuquerque, NM, United States
Registered: 2 Jan 2008
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Re: Different approaches to HDR stitching?
Posted: 13 Feb 2008 at 15:09 GMT
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Robert
You can tone down the "HDR look" in Photomatix Pro by dialing down the Saturation slider during the Tone Mapping or after, just open the TIFF in Photoshop and reduce the Saturation there.
Five to 9 shots starting +2 or +3 is often necessary for interior scenes when you have a modrate lighting in a Living Room with bright windows that have a view of the mountains. Or very dark details in the room like dark leather furniture, wood floors & trim, etc. I've done the same for outdoor scenes because the forest & trees are so much darker than the sky and foreground. The broader the Contrast of the scene, the more shots you usually need to cover the range.
Also, Photomatix Pro now has a selection when setting up the HDR Compiste; "Attempt of eliminate Ghosting" and two sub-selections "Moving Objects" and "Ripples" that help a lot when trees and leaves and moving in the wind.
You might give it a try. There's a full functioning trail version that watermarks the results until you buy the program for $99. Website is www.HDRSoft.com
Doug Aurand
Albuquerque, NM
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Robert Piontek
Posts: 97
Location: Germany
Registered: 26 Jul 2007
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Re: Different approaches to HDR stitching?
Posted: 13 Feb 2008 at 17:55 GMT
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I tried the ghosting features in Photomatix but didn't find that it made much difference.
I always used the tone compressor option of Photomatix, and was basically happy with the results, except for the ghosting problems. Actually I couldn't understand why these images weren't watermarked as well, because for me there was no incentive to purchase a license.
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bigwade
Posts: 250
Location: Netherlands
Registered: 19 Oct 2005
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Re: Different approaches to HDR stitching?
Posted: 13 Feb 2008 at 23:08 GMT
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John Houghton said: Your mention of black corners prompted me to check whether the corners should be masked. (It didn't occur to me to do this last week). I did a quick test just now and confirmed that it does indeed make a difference and is recommended. A mask can be conveniently applied via an action when converting from RAW with ACR.
Thanks John ! , it should be in a tutorial somewhere
Have Fun
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Doug Aurand
Posts: 484
Location: Albuquerque, NM, United States
Registered: 2 Jan 2008
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Re: Different approaches to HDR stitching?
Posted: 14 Feb 2008 at 5:46 GMT
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Robert
In the "Tone Mapping" there's now a choice of "Method", either the Tone Compressor or the newer Details Enhancer.
The Details Enhancer produces very different results.
There've been several improvements in the latest versions that make Photomatix Pro 2.5 worth taking another look at
Doug Aurand
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Skridlov
Posts: 116
Location: United Kingdom
Registered: 12 Nov 2007
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Re: Different approaches to HDR stitching?
Posted: 14 Feb 2008 at 17:13 GMT
updated: 14 Feb 2008 at 17:34 GMT
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Thanks to everyone for these suggestions. There seem to be an immense range of both variables and options in how to achieve decent HDR results. I'm probably pushing my limited abilities in trying to solve this as well as the basics of spherical stitching. I'll certainly try enfuse though.
On the issue of the number of shots required, the problem seems to be that if one uses the bracketing function rather than resetting the speed for each shot (with consequent likelihood of slight movement of the camera) the range is confined to +/- 2 stops assuming 5 shots. This is not sufficient for the contrast in the situations I'm currently experimenting with.
Meanwhile I have encountered another oddity connected with the blend priority setting - which I'll post elsewhere.
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Doug Aurand
Posts: 484
Location: Albuquerque, NM, United States
Registered: 2 Jan 2008
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Re: Different approaches to HDR stitching?
Posted: 15 Feb 2008 at 5:24 GMT
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Skridlov
I manually change the shutter speed for the 5 to 10 shots I take for each of my real estate stills. Usually 15 to 20 scenes for each home
I have a 10 lbs ballust (a barbell) to stabilize the whole tripod & camera setup and use a remote shutter release so I'm not touching the camera when the shutter is operated.
When I have Photomatix Pro composite the 5 to 7 shots I choose, I have it automatically align them and, much to my surprise, it rarely changes the position of any of the shots. If it does, the resulting image is a pixel or 2 wider or taller, but never more than 2 pixels on a 3888 x 2592 pixel image.
I only really need the ballust on carpeted floors. I sometimes don't use it on ceramic tile or wood floors.
You can more than likely get the range you want without much effort. I think you're making this harder that it really is. Take it from some one who composites at least 20 HDR photos every day
I just finished processing photos of 2 homes 20 shots each, would you like me to e-mail you a couple shots?
Doug Aurand
Albuquerque, NM
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Robert Piontek
Posts: 97
Location: Germany
Registered: 26 Jul 2007
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Re: Different approaches to HDR stitching?
Posted: 15 Feb 2008 at 8:28 GMT
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I could live with manual bracketing for a single image, but not for a spherical pano!
More expensive cameras will to auto bracket a wider range with more shots.
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