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Author Topic: HDR Panoramas  (Read 5829 times)

sanfairyanne

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HDR Panoramas
« on: July 08, 2009, 12:56:20 pm »

I have just been given PTgui the Stitching software and I have CS4  and Photomatix on my Mac. Lately I've been taking some panoramas using a Nodal Ninja QTVR head. I took a picture the other day from Dead Horse Point near Canyonlands National Park. As a Panorama it's quite promising, however, I bracketed each shot so I should be able to Stitch then HDR. I must be doing something wrong, I stitch all the bracketed exposures together then I'm left with three pano's. One a stop under, one mid range and one a stop over. The problem is they all come out at a different image size and I can't then put them into Photomatix.

I wondered how people go about doing this, I know it can be done and I should have good enough software to do it. Should I perhaps HDR each image first then Stitch?


Any help on this would be appreciated.
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Farkled

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« Reply #1 on: July 08, 2009, 05:17:40 pm »

What happens if you stitch the darks, then the middles and then the lights; that leaves you with a number of panos to be HDR'd?
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markhout

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« Reply #2 on: July 08, 2009, 05:36:03 pm »

My description for this image may be of some help: http://www.flickr.com/photos/markhout/2845147470/

Absolutely - HDR first, then stitch. (Yes, it's tedious, but worth while!)
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Luis Argerich

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« Reply #3 on: July 08, 2009, 06:32:56 pm »

Take the first set of shots, the underexposed ones.
Load in PtGUI, align the images.
Just before creating the pano save as template.

Then for the next 2 series just load the shots and apply the template.

You end up with 3 panoramas that you can merge in Photomatix.

In my installation that is some years old if the pano is too big photomatix runs out of memory when that happens I change the workflow to creating the HDRs first and then assembling the panorama based on the Photomatix output.

Hope it helps.
Luigi

BernardLanguillier

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« Reply #4 on: July 08, 2009, 06:55:30 pm »

PTgui Pro will be able to do pretty much automatically for you, but you'll need to read the manual.

There is an HDR tab in which you can select what mapping technique you want to use. I tend to prefer the results from the fusion based algo.

The great thing is that PTgui is going to align the images both within a single pano, but also between bracketed shots, which will eliminate the problem you are seeing with the inferior CS4 solution.

You can even export from PTgui a layered PS file where each of the bracketed stitched image is on its own layer. You can then mask them and edit the default HDR blending computed automatically by the Fusion algo.

Autopano pro is even better at doing all this completely automatically.

One thing is sure, don't use CS4 if you are serious about all this.

Cheers,
Bernard

Chris Stomberg

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« Reply #5 on: July 08, 2009, 06:57:31 pm »

Quote from: sanfairyanne
I have just been given PTgui the Stitching software and I have CS4  and Photomatix on my Mac. Lately I've been taking some panoramas using a Nodal Ninja QTVR head. I took a picture the other day from Dead Horse Point near Canyonlands National Park. As a Panorama it's quite promising, however, I bracketed each shot so I should be able to Stitch then HDR. I must be doing something wrong, I stitch all the bracketed exposures together then I'm left with three pano's. One a stop under, one mid range and one a stop over. The problem is they all come out at a different image size and I can't then put them into Photomatix.

I wondered how people go about doing this, I know it can be done and I should have good enough software to do it. Should I perhaps HDR each image first then Stitch?


Any help on this would be appreciated.

If you have the current pro version of ptgui, which I just acquired, you can just load all the shots into ptgui, and it will stitch everything into an HDR pano and let you output in a variety of ways. I just did my first one of these over the weekend: 2 rows of 4 by 3 exposures each (24 shots). Flowers at relatively close distance - it worked really very well.  Two shots needed my input to generate control points, but it was otherwise automagical. I have the print sitting in front of me at my desk and I can't help staring at it. Dumb composition, but technically very cool. I'm really inspired to try this on a number of subjects just for the better resolution and dynamic range. With care you can get really smooth tonality out of this.  My Rebel XT is seeming like a cool tool again (using panosaurus head by the way). They have a crippled demo version that lets you at least see how it would do with your shots, but will also scribble "ptgui" all over your shot. Might be worth a try. For me it was unbelievably easy.

My guess is that the HDR controls in PTGUI are not quite as rich as Photomatix, but I wouldn't know. The final render also took a long, long time on my laptop. The final 16 bit tiff is over 130Mb. I guess that takes time to cook up.
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AndrewKulin

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« Reply #6 on: July 08, 2009, 06:58:33 pm »

Quote from: luigis
Take the first set of shots, the underexposed ones.
Load in PtGUI, align the images.
Just before creating the pano save as template.

Then for the next 2 series just load the shots and apply the template.

You end up with 3 panoramas that you can merge in Photomatix.

In my installation that is some years old if the pano is too big photomatix runs out of memory when that happens I change the workflow to creating the HDRs first and then assembling the panorama based on the Photomatix output.

Hope it helps.
Luigi

Why would you align the under-exposed images first?  Is there a technical reason making this the way to do it?

Would it not be better to align the middle exposure first and then save the template and apply that to the over and under-exposed images?  That way if you need to adjust any of the control points or manually define some to begin with because the software could not generate these automatically for one or more pairs of photos, you would be able to see the image better to do that.  I imagine the under-exposed image could be quite difficult to work with for defining control points.

Andrew
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JeffKohn

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« Reply #7 on: July 08, 2009, 08:10:30 pm »

My workflow for this with PTGui Pro is as follows.

- Add all the images to the project and let it find control points. It will detect the bracketed exposures and prompt you to 'link' them. I prefer Exposure Fusion to HDR, as I think it tends to look more natural.

- On the Exposure/HDR tab, configure the settings for Exposure Fusion.

- In the output options, check both of the following options: "Blend Planes" and "Exposure fused panorama".

When you do this, PTGui will stitch all three brackets using the same control points, so that everything aligns properly. It will output four files: the final blended version, plus stitched versions for each individual exposure. This way, I have four files to work with for my final exposure blending. Sometimes I can just used the "fused" panorama, sometimes I'll also use the blend planes as layers in Photoshop. Or, if you wanted you could run the blend planes through Photomatix for final tonemapping (you may have to use the batch mode to avoid memory problems depending on your filesizes, though).

To me stitching first and then blending/tone-mapping is preferable. I know some people get good results doing it the other way around. The issue I see is that the Details Enhancer tone-mapping in Photomatix is content-based; you could run all your images through with the same settings and end up with uneven results that PTGui will then have to try to blend.
« Last Edit: July 08, 2009, 08:11:58 pm by JeffKohn »
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Jeff Kohn
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tived

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« Reply #8 on: July 09, 2009, 02:30:52 am »

I second Bernard here.

You have the ability within PTGui 8.x to do this, and it does a nice job at it too. it will link the shots, if it detects them as being HDR or bracket series, at least you can choose it to do so.

Henrik

Quote from: BernardLanguillier
PTgui Pro will be able to do pretty much automatically for you, but you'll need to read the manual.

There is an HDR tab in which you can select what mapping technique you want to use. I tend to prefer the results from the fusion based algo.

The great thing is that PTgui is going to align the images both within a single pano, but also between bracketed shots, which will eliminate the problem you are seeing with the inferior CS4 solution.

You can even export from PTgui a layered PS file where each of the bracketed stitched image is on its own layer. You can then mask them and edit the default HDR blending computed automatically by the Fusion algo.

Autopano pro is even better at doing all this completely automatically.

One thing is sure, don't use CS4 if you are serious about all this.

Cheers,
Bernard
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ChrisJR

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« Reply #9 on: July 09, 2009, 05:43:14 am »

Have you tried batch processing in Photomatix?

I shoot a lot of bracketed panoramas (sometimes a little HDR) and always batch process the bracketed images in Photomatix first and then stitch resulting images in either PTGui / Autopano.

Blending the images in Photomatix is an awful lot quicker than PTGui and if done correctly you'll get nicer quality images.
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Luis Argerich

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« Reply #10 on: July 09, 2009, 11:41:36 am »

Yes, you are right, It is better to start with the normal exposure since it would be better for control point assigment.

I don't like the way ptgui creates hdr so I still prefer to do the HDR with photomatix and the pano part with ptgui.


Quote from: AndrewKulin
Why would you align the under-exposed images first?  Is there a technical reason making this the way to do it?

Would it not be better to align the middle exposure first and then save the template and apply that to the over and under-exposed images?  That way if you need to adjust any of the control points or manually define some to begin with because the software could not generate these automatically for one or more pairs of photos, you would be able to see the image better to do that.  I imagine the under-exposed image could be quite difficult to work with for defining control points.

Andrew

bill t.

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« Reply #11 on: July 09, 2009, 11:58:12 am »

Blending or HDR'ing individual stacks before blending in Photomatix has some quality advantage for shots where the lighting is not even across the entire pano.

For instance, wide panos where the sun is low in the sky will usually have significantly different contrast and brightness in each panel. In these cases blending individual panels before stitching with optimal adjustments per panel usually produces (for me) a superior result compared to blending entire panos in PTGui or whatever.

What I really want is software that will display a roughly stitched pano with individual sets of blending/HDR control sliders for each panel.
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