Jonathan Ang
Posts: 15
Location: Singapore, Singapore
Registered: 17 Aug 2012
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Editing workflow & HDR
Posted: 25 Aug 2012 at 15:33 GMT
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Hi guys, John,
I've raised this question inside my previous thread, but I feel the main point of the thread has already been answered so I would like to start a new one.
Here's the thing:
on a very typical scene where HDR works somewhat fine, I would:
1)batch process 3 bracketed scenes into 1,
2)PTGui stitch the processed photos
Just yesterday, I tried:
1)stitching the same exposures,
2)HDR processing the entire equirectangular file
3)re-blend HDR to tone it down.
(or skip step 2 and straight to manual blending)
I realised that this method gives me more control (would be my preferred method):
however due to editing the equirectangular file, when I passed the pano to pano2vr, I see a very visible stitch line. What should I do?
On weird occasions, the processed equirectangular file that opens in pano2vr has a completely round black hole at the nadir and zenith. Is there a degree of processing that SHOULD NOTbe done to the equirectangular file?
ps, I process all in full files, raw->tiff 16bits until the final panoramic creation step.
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Smooth
Posts: 4013
Location: Mount Panorama, Australia
Registered: 21 Jul 2004
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Re: Editing workflow & HDR
Posted: 25 Aug 2012 at 15:59 GMT
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You should "flatten" the image before saving. If your HDR program/procedure has a panorama 360 wrap switch - enable it.
You should check you have maintained a pure 2:1 aspect ratio for the equirectangular image. I.E: 6000x3000 or 10000x5000 It MUST be twice a wide as tall EXACTLY in pixels.
Regards, Smooth 
www.omnipix.com.au
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vrbali
Posts: 194
Location: Bali, Indonesia
Registered: 12 Feb 2010
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Re: Editing workflow & HDR
Posted: 26 Aug 2012 at 15:24 GMT
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Experienced the same problem with Photomatix a few versions ago, especially a pinched problem at the zenith (even with 360 wrap around selected). Reported the problem to Photomatix creators, but didn't try the method with latest versions yet. It's was one of the reason why I stopped stitching prior to merging to hdr/tonemapping.
You could try if you get the same problem with different programs like comparing Photomatix and EnfuseGUI output to locate where the problem comes from.
Also experience a seam when downsizing an equirectangular with Photoshop.
It seems to be caused by partly transparant pixels at the sides after downsizing. I typically copy the layer 3 - 4 times and merge them (using an action) to get rid of the transparant side pixels.
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Jonathan Ang
Posts: 15
Location: Singapore, Singapore
Registered: 17 Aug 2012
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Re: Editing workflow & HDR
Posted: 26 Aug 2012 at 18:38 GMT
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Thanks Marco,
so no stitching prior to hdr. hmm.
I only do this if i feel the HDR outputs from batch HDR don't cut it, and need to do some manual blending. I unsure if manual blending made those seams.
I'd take note of downsizing an equirectangular with PS. Is it not okay to let the VR program do the resizing?
Smooth,
yes I do flatten them.
It happened twice, re-exporting the equirectangular photo and putting into pano2vr normally solves it. (The black holes zenith and nadir.) If I don't do any editing and go from PTGui>pano2vr, no issues. Weird but I'll take note again when it happens.
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Smooth
Posts: 4013
Location: Mount Panorama, Australia
Registered: 21 Jul 2004
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Re: Editing workflow & HDR
Posted: 27 Aug 2012 at 5:09 GMT
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The black holes at the Zenith and Nadir come about because a pixel gets lost in the downscale (or somewhere else). So you end up with say 8800x4399px instead of 8800x4400. Once this pixel is lost you no longer have the expectant equirectangular image of 2:1 ratio.
Don't forget you have the Photoshop option of Filter>Other>Offset>(Horizontal Numerals XXXX)>Wrap Around (radio button) and check/tick the preview option. You can then see what is happening at the panorama wrap.
Regards, Smooth
www.omnipix.com.au
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John Houghton
Posts: 3710
Location: Hitchin, United Kingdom
Registered: 17 Jan 2005
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Re: Editing workflow & HDR
Posted: 27 Aug 2012 at 6:56 GMT
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Marco W said: Also experience a seam when downsizing an equirectangular with Photoshop.
It seems to be caused by partly transparant pixels at the sides after downsizing.
I have never seen this happen when downsizing a background layer. As Smooth said, you must only downsize a flattened image. You can check for a seam before and after the resizing by using Filter->Other->Offset, with wrap checked. If you shift by half the width, the seam will then fall exactly in the middle of the panorama. If you have a flattened image that develops semi transparent pixels at the edges when resized down, I would be interested to see it.
John
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Jonathan Ang
Posts: 15
Location: Singapore, Singapore
Registered: 17 Aug 2012
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Re: Editing workflow & HDR
Posted: 27 Aug 2012 at 19:14 GMT
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Thanks,
this is spot on. Just happened again and I wouldn't have checked the pixel ratio if I haven't learnt this, thanks!
Marco is right, there is a missing clipped pixel. I checked - direct from photomatix output (even with 360on.) I suppose I should update!
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Jonathan Ang
Posts: 15
Location: Singapore, Singapore
Registered: 17 Aug 2012
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Re: Editing workflow & HDR
Posted: 27 Aug 2012 at 21:11 GMT
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The update solved the pinched zenith and nadir,but it doesn't solve the weird seam at the ends of the equirectangular pano.
www.panoguide.com/forums/qna/4468/
this is an old thread I dug. seems the problem still exists =(
I suppose if stitch/HDR is a bad idea, i've gotta go with HDR/stitch
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