Stitching multiple exposures, HDRI result

[kimaldis]

Stitching multiple exposures, HDRI result

by kimaldis » Mon Dec 17, 2012 10:46 am

I'm stitching multiply exposed images into a panorama using Autopano Giga, outputting to EXR 32 bit and I'm having a great deal of trouble getting as much detail in highlights as I can by merging exposures to HDR using Photoshop CS6. This particular shot is a sunset and Autopano is clipping out the brighter cloud detail. I've tried using Fusion, the highlight detail refuses to appear. Any thoughts?

[mattmerk]

by mattmerk » Wed Mar 20, 2013 8:27 pm

I too have this problem. If I load the Autopano Giga Pro output into software that can read floating point values, the whites are clipped at 1.0. True HDRI used for image based lighting in 3D software such as Maya or 3DS Max, or any other, relies on true floating point irradiance maps with white values above 1. I've been struggling with this for days under the assumption that I am doing something wrong, but after hours of RTFM and pressing every available button in the software, I am coming to the conclusion that this is a software limitation in Autopano Giga. I think I'll be recommending PTGui to my friends from now on unless someone can point out how I have screwed up, which is still a great possibility.

I like how the software works. It is just sad that getting true HDRI output working is so difficult, or even impossible.

[klausesser]

by klausesser » Wed Mar 20, 2013 9:51 pm

I too have this problem. If I load the Autopano Giga Pro output into software that can read floating point values, the whites are clipped at 1.0. True HDRI used for image based lighting in 3D software such as Maya or 3DS Max, or any other, relies on true floating point irradiance maps with white values above 1. I've been struggling with this for days under the assumption that I am doing something wrong, but after hours of RTFM and pressing every available button in the software, I am coming to the conclusion that this is a software limitation in Autopano Giga. I think I'll be recommending PTGui to my friends from now on unless someone can point out how I have screwed up, which is still a great possibility.
I like how the software works. It is just sad that getting true HDRI output working is so difficult, or even impossible.

APG can very well output "true" HDR as .hdr and .exr. I use it in Maya, Maxwell and Cinema4D for IBL. I use 3 or 7 or 9 steps bracketing. No problem.

What APG cannot do is tonemaping. Here it uses fusioning instead.

best, Klaus

[mattmerk]

by mattmerk » Thu Mar 21, 2013 6:23 am

Thanks for the reply Klaus. Very helpful. Much appreciated.

Now I know that Autopano Giga can at least do what I was told it could do. Now I just need to figure out how. Like I said, I have spent a lot of time with the manual and I am still not getting true HDR output. When I select HDR output and file type to either .exr or to .hdr with a 32bit color depth, my output is clamped at 1.0.

I have tried merging my stacks in advance in photoshop as 32bit HDR images that I can load in a program like Nuke or After Effects and color correct them down to see all the detail in the highlights. In other words, they are true HDRI, suitable for IBL in any 3D app. (I really don't care at all about tone mapping. All I care about is true HDRI, and I find it a shame that people call tone mapped LDR images HDRI. But that is a rant for another time.)

Once I load my bracketed images into Autopano Giga and make a pano, in the rendered output, my highlights are all clipped at 1.0. There should be way more info in a spherical panorama in those highlights well above 1. I get the same results in Autopano Giga if I load the images as stacks of bracketed exposures or if I pre-merge them into 32bit HDR .exr files and load those.

So, what am I missing here? Is there a button somewhere I missed? My panos look fine in terms of stitching. They just don't contain color values above 1.0 and no detail in the "overexposed" ares (which in an HDRI, there are really no overexposed pixels, except for maybe the sun).

Just a point in the right direction would be most appreciated.

I'm attaching four images.

1. A UI screen capture of my render settings.

2. The distorted one is a premerged HDRI out of Photoshop showing a split screen color correction bringing the white values down to reveal the data in the highlights above 1.

3. The flattened image is a blow up and color corrected cropped screen grab of the .hdr panorama file showing the exact same color correction where there is no information above 1 and is brutally clipped.

4. And the pano, to show that the distortion is fine.

MM



>APG can very well output "true" HDR as .hdr and .exr. I use it in Maya, Maxwell and Cinema4D for IBL. I use 3 or 7 or 9 steps bracketing. No problem.

>What APG cannot do is tonemaping. Here it uses fusioning instead.

>best, Klaus

[klausesser]

by klausesser » Thu Mar 21, 2013 12:35 pm

Thanks for the reply Klaus. Very helpful. Much appreciated.

Now I know that Autopano Giga can at least do what I was told it could do. Now I just need to figure out how. Like I said, I have spent a lot of time with the manual and I am still not getting true HDR output. When I select HDR output and file type to either .exr or to .hdr with a 32bit color depth, my output is clamped at 1.0.

I have tried merging my stacks in advance in photoshop as 32bit HDR images that I can load in a program like Nuke or After Effects and color correct them down to see all the detail in the highlights. In other words, they are true HDRI, suitable for IBL in any 3D app. (I really don't care at all about tone mapping. All I care about is true HDRI, and I find it a shame that people call tone mapped LDR images HDRI. But that is a rant for another time.)

Once I load my bracketed images into Autopano Giga and make a pano, in the rendered output, my highlights are all clipped at 1.0. There should be way more info in a spherical panorama in those highlights well above 1. I get the same results in Autopano Giga if I load the images as stacks of bracketed exposures or if I pre-merge them into 32bit HDR .exr files and load those.

So, what am I missing here? Is there a button somewhere I missed? My panos look fine in terms of stitching. They just don't contain color values above 1.0 and no detail in the "overexposed" ares (which in an HDRI, there are really no overexposed pixels, except for maybe the sun).

Just a point in the right direction would be most appreciated.

I'm attaching four images.

1. A UI screen capture of my render settings.

2. The distorted one is a premerged HDRI out of Photoshop showing a split screen color correction bringing the white values down to reveal the data in the highlights above 1.

3. The flattened image is a blow up and color corrected cropped screen grab of the .hdr panorama file showing the exact same color correction where there is no information above 1 and is brutally clipped.

4. And the pano, to show that the distortion is fine.

MM

>APG can very well output "true" HDR as .hdr and .exr. I use it in Maya, Maxwell and Cinema4D for IBL. I use 3 or 7 or 9 steps bracketing. No problem.

>What APG cannot do is tonemaping. Here it uses fusioning instead.

>best, Klaus

Let´s try to avoid misinterpretations:

Using bracketed sets to generate a HDR file means:
A) to open this HDR file in a dedicated HDR-application to be viewed. You can´t display native HDR.
B) to use it for IBL in an application like Maxwell, Maya, Cinema, Max or whatever.

Case A) i suggest to open the HDR files in Photomatix, Oloneo, HDR-LightStudio or familiar applications.
Case B) it should be obvious that you see the tonal range of your HDR only after you rendered the scene . .
How much you can judge it in the editor resp. preview depends on the application.

So my advise: judge them in a dedicated app like Photomatix, Oloneo or HDR-LightStudio or "specialists".

best, Klaus

[gkaefer]

by gkaefer » Thu Mar 21, 2013 2:04 pm

before we can suggest the correct workflow for you we need very Basic Input autopano is relying on...

your Input Images have which Format: jpg, tiff 8bit no layer, tiff 16bit no layer, .hdr, .exr files?
you do use the autopano Group feature? (Group window->right mouse click->Group N Images...)
your Images are recognized as bracketed Images in autopano? (Group window-> the Image stacks are signed with "BRK" in the preview)

you wanna do fusing
you wanna do tonemapping
you wanna create HDR Output Images (.exr or .hdr Format - and with no tonemapping at all in consequence)

if you can answer These qestions, than you can according to autopano docu decide which workflow is the only correct one (to achieve your Output using autopano)

so if you need real .exr output for IBL than I would suggest like Klaus to use Photomatix or oloneo to create .exr files from your Image stacks first. Here you have much more influence on the result and you can do a test tonemapping from your exr files too.

These .exr Images than you load into autopano using "Workflow Case F" to produce real a real .exr pano from...
http://www.autopano.net/wiki-en/action/view/LDR_/_HDR_:_How_it_works

Georg

Last edited by gkaefer on Thu Mar 21, 2013 2:05 pm, edited 1 time in total.

[klausesser]

by klausesser » Thu Mar 21, 2013 2:22 pm

so if you need real .exr output for IBL than I would suggest like Klaus to use Photomatix or oloneo to create .exr files from your Image stacks first. Here you have much more influence on the result and you can do a test tonemapping from your exr files too.

Hey Georg!

Sorry - you took me wrong: it´s NOT about using Photomatix or so FIRST - it´s about using it AFTERWARDS!

You don´t need to HDR single images FIRST when you need HDR-output. You put the stacks into APG and let it output a HDR/exr file. THIS you put into
a HDR application for judging the result and/or apply tonemapping to it . . IF you want. The TO doesn´t want to apply tonemapping - he wants to use native HDR
for IBL/GL as i understood him.

best, Klaus

[gkaefer]

by gkaefer » Thu Mar 21, 2013 2:36 pm

so if you need real .exr output for IBL than I would suggest like Klaus to use Photomatix or oloneo to create .exr files from your Image stacks first. Here you have much more influence on the result and you can do a test tonemapping from your exr files too.

Hey Georg!

Sorry - you took me wrong: it´s NOT about using Photomatix or so FIRST - it´s about using it AFTERWARDS!

You don´t need to HDR single images FIRST when you need HDR-output. You put the stacks into APG and let it output a HDR/exr file. THIS you put into
a HDR application for judging the result and/or apply tonemapping to it . . IF you want. The TO doesn´t want to apply tonemapping - he wants to use native HDR
for IBL/GL as i understood him.

best, Klaus

ok. i see. (first :: afterwards)
I know I dont Need th HDR single Images first... but kimaldis did not out the info which Format his Images does have he's using...
... in case he would have used .exr or .hdr Images first, than all his attampts to use fusing or Color correction would inescapably have to fail...
Georg

Last edited by gkaefer on Thu Mar 21, 2013 2:36 pm, edited 1 time in total.

[mattmerk]

by mattmerk » Thu Mar 21, 2013 7:35 pm

Well all that doesn't make sense at all to me then. I felt hopeful for a second there but I really don't have any idea what I might be doing wrong here if in fact Autopano Giga can actually produce true HDR images. (It isn't like I haven't walked, step by step, for days, through every permutation of every workflow in the documentation.)

I bring my Autopano Giga output into a totally floating point supported app like Nuke and the white values are definitely clipped. It doesn't matter if I pre-make the HDR exrs in any app that can do it and then bring them into Autopano Giga, or if I bring in LDR bracketed stacks. When I make a HDR pano, I still get clipped whites. See my images above. The color corrected split screens were done in Nuke which has a totally floating point color pipeline. I could repeat this in Shake, After Effects or even Photoshop. I have even tried outputting individual images along with the pano in Autopano Giga and they too are clipped.

As far as I am concerned, in this conversation, we need never talk about tone mapping again. Only HDRI both in (either through stacks of bracketed LDR images or pre-made HDR images) and out which means a 32 bit floating point image that when displayed on a computer monitor has values above what the monitor is capable of displaying and when color corrected, lowering the brights, suddenly you see image detail you couldn't see before. I don't know how to describe this more simply.

As I understand it Klaus, you get different results than me? Can I maybe get a pano you have created with color data above 1.0, like in my photoshop HDRI image (#2) above? I've been doing IBL for big studio feature films for nearly ten years. I just wanted an app that could give me higher resolution HDRI spheres that my trusty chrome ball bearing.

And for everyone's information, you can do IBL with LDR images. It might even look okay in some cases. It is just a matter of loading a LDR image into the part of the UI in whatever 3D app that asks what image you want to use for your environment lighting.

I'd like to see one of your HDR panos just to see if you actually have an HDRI with color values (which actually represent photon energy) above 1. Or point me on the web to a pano done in Autopano Giga that was designed for IBL.

I have an idea about another pipeline that might work but it involves outputting a pano for each bracket step and loading all of them into an app that can assemble them into a true HDRI. I know that would work. I just haven't determined if I can get Autopano Giga to output a pano for each bracket step.

And thanks again. I really appreciate it. I know it isn't like I am paying you or anything.

[mattmerk]

by mattmerk » Thu Mar 21, 2013 7:41 pm

And just so you and I know we are on the same page, "A) to open this HDR file in a dedicated HDR-application to be viewed. You can´t display native HDR." <--- THAT! Yes! That is exactly what I have been saying. However, if you load HDRI into an app with a 32bit, floating point, color pipeline, you can color correct the images down, darken them, lower their exposure, and suddenly reveal image info in the highlights you couldn't see before.

This is what I have been doing to check the output of autopano giga and I am finding it is NOT actually high dynamic range. It is 8 oz. of LDR sauce dumped into a 32 bit, 50 gallon drum.

[mattmerk]

by mattmerk » Thu Mar 21, 2013 7:44 pm

(...like loading a JPEG and saving it out as a .hdr file. You don't actually increase any information in the 8 bit LDR JPEG just by saving it as a 32 bit file. Hence 8 oz. to 50 gallon drum metaphor. Just to be clear.)

[mattmerk]

by mattmerk » Fri Mar 22, 2013 8:21 pm

I am rapidly coming to the conclusion that Autopano Gig does not actually do HDRI. Like I said, I have a decade of image based lighting experience in feature films and the HDRI output of Autopano Giga is NOT actually HDRI. If the values above 1.0 (in floating point) clip at white and there is no detail wehn you bring them down (through grading/manipulation) in time tested visual effects compositing software, what you have is a case of false advertising.

Like I said earlier, you can load 32 bit low dynamic rang images into any software that does image based lighting and get acceptable results. (Just because they are 32 bit does NOT make them HDR. You could easily have quantized bands of integers representing your color in a 32 bit floating point wrapper.) You'd get better results with your IBL, however, if the images you were using actually were real HDRI.

I'd be totally happy to be wrong about this. I WANT to be wrong about this! But based on the results of my week long testing binge here, which I have been able to replicate on various computers in my facility, I don't actually think Autopanogiga is sending floating point values through it's internal pipeline. Please, again refer to my screen grab of my output settings from Autopano Giga above. And then check out this movie I made illustrating the problem.

https://vimeo.com/62454188

Now I am going to try and track down the programmers and ask them. Anyone want to maybe point me to where I can send THAT email?

Thanks again.

[mediavets]

by mediavets » Fri Mar 22, 2013 8:56 pm

Now I am going to try and track down the programmers and ask them. Anyone want to maybe point me to where I can send THAT email?

Thanks again.

Try the contact form:

http://www.kolor.com/contact.html

and/or

alexandrejenny@kolor.com (CEO of Kolor)

[mattmerk]

by mattmerk » Sun Mar 24, 2013 7:32 am

So, I've sent emails and messages and heard nothing, no reply. Meanwhile, I downloaded PTGUI Pro and made a 13000 pixel wide HDRI panorama in about 5 minutes. Here are my immediate results. Lo and behold. Actual HDRI with white values well above 1. In the first image, I cropped out a small section of the PTGUI pano and color corrected part of it. On the left, it is not color corrected and appears overexposed. On the right shows my color correction bringing down the white point revealing all the floating point values above 1, NOT clipped by PTGUI. THIS is real HDRI. THIS is HDRI acceptable for real IBL in professional VFX applications. This is NOT what Autopano Giga does when I select HDR output. In the second image, you can see the un-color corrected, over exposed pano at the top half and on the bottom half, a color correction darkening the image and revealing the detail in the over exposed areas out the windows.

Now again, please, someone tell me I am wrong. I'd like to think I didn't waste the money I spent on Autopano Giga for the purposed I bought it for. I've never used PTGUI before and it required no reading of any documentation whatsoever to get these results. I spent a week with the Autopano Giga documentation.

I think Autopano Giga does a better job of stitching and PTGUI has numerous small misalignment errors, but this is a show stopper for VFX professionals.

Matthew Merkovich

Last edited by mattmerk on Sun Mar 24, 2013 7:36 am, edited 1 time in total.

[HansKeesom]

by HansKeesom » Sun Mar 24, 2013 3:23 pm

........... I've never used PTGUI before and it required no reading of any documentation whatsoever to get these results. I spent a week with the Autopano Giga documentation.

......

Matthew Merkovich

Remarkable, I showed Autopano to a 62 year photographer with memory problems. She had been fighting with PTGUI for a long time. Autopano she understood immediately....

Maybe you should allow a bit more then two days for kolor to get to your email, certainly when you send it on friday.....

Last edited by HansKeesom on Sun Mar 24, 2013 3:25 pm, edited 1 time in total.

[mattmerk]

by mattmerk » Sun Mar 24, 2013 11:39 pm

I had no problems making panoramas with Autopano Giga. That was easy. Took me the same 5 minutes to figure out as PTGUI and no need for the documentation either.

My week with the documentation was in getting the HDR output to work, which now seems to NOT actually work. I had to exhaust every possibility that I just couldn't figure out the software. I never have given anyone reason to say to me, "RTFM!" nor do I ever want to. (You're welcome.)

So Hans, please have your 62 year photographer explain to me just how a 32 bit HDR image with no pixel RGB values above 1 is actually a representation of the photon energy present in any HDR panorama not taken in a dark closet.

That is where this thread started. Not with stitching (which I already pointed out, my PTGUI first attempt rendered all manner of minor stitching errors), but with Autopano Giga's "HDR" actually being LDR wrapped in a 32 bit file format with no RGB values above 1.

So far, in this forum, no one has addressed the issue first brought up months ago (not even by me--I didn't even start this thread) which is, where does the highlight detail go? It should be there in the .hdr or .exr, in values above what your monitor/graphics card can represent but recoverable in software as simple and ubiquitous as Photoshop. Instead, various other red-herring issues from tone mapping to how the images get fused to workflow have been brought up. I won't lie; It has been a bit frustrating.

Maybe, if anyone here wants to investigate this other potential application for Autopano Giga, beyond simply stitching LDR panoramas, (if the HDR throughput actually ever gets fixed or If someone can point out my stupidity in not being able to figure it out), go ahead and spend some time here: http://www.hdrshop.com

That piece of software, HDR Shop, actually handles 32 bit floating point HDRI they way it should actually work--the way this guy, http://www.pauldebevec.com, (whom I casually know, by the way) designed and invented it.

Meanwhile, If anyone wants to compare my HDRI output directly from both Autopano Giga and from PTGUI, have at 'em.

http://mattmerk.com/HDRItest/

[aaronpriest]

by aaronpriest » Sun Mar 24, 2013 11:52 pm

I have this same problem with the autoblend feature of Photoshop (even CS6), if you run it on 32-bit images. You will lose all highlight data and have just blown out white skies that no other software can recover. The data just gets chopped off after a certain brightness level.

[aaronpriest]

by aaronpriest » Sun Mar 24, 2013 11:53 pm

And PTGui as a workaround is not a solution as the stitching leaves errors. Sigh...

[mattmerk]

by mattmerk » Mon Mar 25, 2013 12:02 am

Aaron, in Hotoshop (CS6 for me) are you using the File/Automate/Merge to HDR PRO functionality? If you do that with bracketed images representing the brightest and darkest exposures, you should be getting 32 bit float results.

I just uploaded a photoshop generated .exr file made from 10 brackets spaced out in 2 f-stop increments. I put it with the HDRI pano output of APG and PTGUI here: http://mattmerk.com/HDRItest/

It sure would be great if Autopano Giga, clearly the better stitcher, could get this working.

[mattmerk]

by mattmerk » Mon Mar 25, 2013 12:05 am

It is strange to me because APG seems to load the floating point images just fine. It just can't seem to output HDR.

[aaronpriest]

by aaronpriest » Mon Mar 25, 2013 12:42 am

Aaron, in Hotoshop (CS6 for me) are you using the File/Automate/Merge to HDR PRO functionality? If you do that with bracketed images representing the brightest and darkest exposures, you should be getting 32 bit float results.

I'm not talking about HDR Pro, I'm talking about auto blend feature of Photoshop: where you take several 32-bit .hdr, .exr, or .tif files and merge them into a seamless panorama. Photoshop will do the same thing and spit out a 32-bit file that is missing all the highlight detail. It's got slightly more information than a 16-bit file, but not much. All that information just gets chopped off, much like APG.

[mattmerk]

by mattmerk » Mon Mar 25, 2013 1:49 am

I had a deep suspicion I was misunderstanding you and it turns out I was. Sory about that. I was totally unfamiliar with the term "autoblend" as regards Photoshop. I never really thought of using Photoshop for panorama stitching but now that you mention it, I can't think of a reason why not. So, here goes...

Yeesch. I see what you mean now Aaronpriest. Same results as APG. 32 bit LDR. How adorable.

I'm not surprised though. After Effects, another Adobe product, also commonly clips the highlights when image processing 32 bit input. It is totally inconsistent. Adobe is interested in selling the greatest number of units to the greatest number of people. Most people are hobbyists or even professionals with very limited needs, and don't need floating point color through and through. After all, you can't miss that which you never had.

Still, PTGui at least handles HDR RGB values properly, even if you have to wrestle with it.

I mentioned earlier that if I could get APG to output the stitched brackets, I could merge them in Photoshop to get true 32 bit output. Sadly, after the images have been warped, getting 10 render passes, representing 12 bracketed exposures doesn't seem viable either, but I'll leave that can of worms closed until/if someone from Kolor gets a hold of me.

[aaronpriest]

by aaronpriest » Mon Mar 25, 2013 4:22 am

You can output stitched bracketed layers from both PTGui and AutoPano. The trouble is, most HDR programs will not handle very large panoramas to bring the separate 8 or 16-bit exposures into a 32-bit HDR file. For the time being I gave up on 32-bit panoramas, and I've often been tonemapping or fusing into 16-bit LDR files BEFORE stitching because neither APG nor PTGui have good enough control over the fusion process to do it all in one pass. There are obvious issues however with tonemapping or fusing before stitching, the biggest being inconsistency between images with such a large scene.

[mattmerk]

by mattmerk » Mon Mar 25, 2013 4:57 am

Thanks for the reply. Here is a summary of my experience: I tried disabling all but one layer at a time, but got weird results. Layer 1 (N1) might be at a higher exposure and N2 might be at the bottom of the exposure range. And the rest were all over the place, seemingly randomly. It also appeared that the number of layers that were made into pano layers didn't match the number of exposures. I didn't do a lot of research here because the initial results were so bizarre. I may go back to it, but the best solution would be for Kolor to fix the false advertising and make the software do what they say it can do. Being able to write a .hdr file is not the same as generating true HDRI.

From the product comparision page: "HDR for special effects (saving of the .hdr file) - Yes." <--- The truth is that APG saves a .hdr file but one that doesn't have all the actual HDR info in it.

[klausesser]

by klausesser » Mon Mar 25, 2013 10:58 am

You can output stitched bracketed layers from both PTGui and AutoPano. The trouble is, most HDR programs will not handle very large panoramas to bring the separate 8 or 16-bit exposures into a 32-bit HDR file. For the time being I gave up on 32-bit panoramas, and I've often been tonemapping or fusing into 16-bit LDR files BEFORE stitching because neither APG nor PTGui have good enough control over the fusion process to do it all in one pass. There are obvious issues however with tonemapping or fusing before stitching, the biggest being inconsistency between images with such a large scene.

Hey Aaron, Matt!

Try HDR-processing the bracketed images FIRST. Saving the results as HDR/EXR. Stitch the HDR-images using the xml-import. Render them as HDR/EXR.
Output them as HDR/EXR. Import them to Maya, Maxwell, V-Ray, Cinema ot whatever for IBL.

NO color-manipulation AT ALL in APG - JUST stitching.

best, Klaus

Last edited by klausesser on Mon Mar 25, 2013 11:48 am, edited 1 time in total.