Skridlov
Posts: 127
Location: United Kingdom
Registered: 12 Nov 2007
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Source image orientation scrambling
Posted: 10 May 2008 at 13:27 GMT
updated: 10 May 2008 at 13:56 GMT
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I've encountered this before but here goes again.
I load a set of source images, apply the template and generate a set of auto cp's. This causes several of the images to display in the project assistant as rotated.
I start a new project and reload, apply the template and then creat a pano without generating cp's. This output is pretty good apart from a few relatively minor stitching errors.
I then generate control points again. This time a single image displays as rotated.
Is there a solution in this situation apart from using only manually set cp's?
Edit 1: I've just looked at the images in the CP editor and some are displayed as inverted! These despite being correctly displayed in the Project Assistant.
This is the first time that I have seen auto align cp fail completely.
Edit 2: Running auto align before applying the template (after starting a new project) generates good cp's. Applying the template and optmising FOV, H&V shift gives very good optimisation.
Can anyone suggest what's happening here? And is the second sequence (apply template after cp generation) deficient in any way?
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Macro
Posts: 35
Location: Korea, Republic of
Registered: 5 Sep 2006
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Re: Source image orientation scrambling
Posted: 10 May 2008 at 14:10 GMT
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I've seen a similar rotation problem. The images are all vertical until running auto align. Then one or more are rotated horizontal. When I look at the images in the editor, one or more are all over the place. In my case, the images that are rotating contain repeating patterns that can be found in several images (even out of sequence) and at various orientations. If I move them into place manually with the editor, then they rotate back normal. I've seen the same problem with Autopano. The repeating patterns seem to cause confusion. Manual CP's will correct this, but can be tedious.
David
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Skridlov
Posts: 127
Location: United Kingdom
Registered: 12 Nov 2007
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Re: Source image orientation scrambling
Posted: 10 May 2008 at 14:22 GMT
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Hi Macro
The procedure I describe above (Edit 2) gets round it. It doesn't seem to cause any problem doing things in this order but I stand to be corrected. Looks like a bug to me, but...
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John Houghton
Posts: 2265
Location: Hitchin, United Kingdom
Registered: 17 Jan 2005
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Re: Source image orientation scrambling
Posted: 10 May 2008 at 15:19 GMT
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Roy, The correct procedure to follow when using a template is:
1. Add the images.
2. Apply the template.
3. Generate control points via the Control Points menu on the top bar. (Won't affect the orientation of the images).
4. Optimize manually. If the template is a good one, you won't want to optimize the lens parameters a,b,c.
Don't run Align Images after the template has been applied.
John
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Skridlov
Posts: 127
Location: United Kingdom
Registered: 12 Nov 2007
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Re: Source image orientation scrambling
Posted: 10 May 2008 at 15:29 GMT
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Thank you John
I hadn't even spotted this option. Does this use completely different code to the "align images" command?
BTW I actually just completed a pano using the "wrong procedure" - ie my workaround described in the secon edit of my original post. It seems to be OK. Just good luck?
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John Houghton
Posts: 2265
Location: Hitchin, United Kingdom
Registered: 17 Jan 2005
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Re: Source image orientation scrambling
Posted: 10 May 2008 at 15:48 GMT
updated: 10 May 2008 at 15:52 GMT
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Roy, In your workaround, you use the Align Images button to generate control points and optimize. You then apply the template, which replaces all the parameter values evaluated by PTGui. So all you have left from the Align Images run are the control points. The quality of the control points generated should be no different to doing it via the Control Points menu, though they won't be identical. Possibly PTGui might thin the generated points to remove very bad ones. It's probably better to correct/delete control points after your own optimization with good lens parameters set up by the template. There's a delete worst points option available on the Control Points menu, which can save time.
John
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Skridlov
Posts: 127
Location: United Kingdom
Registered: 12 Nov 2007
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Re: Source image orientation scrambling
Posted: 10 May 2008 at 16:06 GMT
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OK. I left out mentioning a stage in that after applying the template I also added T1/2 points and did a general cleanup deleting bad cp's & adding some manually above the tropical regions and then re-optimised.
It's interesting that the non-aligned test (ie just generate pano from template parameters) wasn't too bad. Is it practicable given the limitations of non-precision panheads to create a template that will give acceptable results without generating cp's? It seems unlikely from my own limited experience.
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John Houghton
Posts: 2265
Location: Hitchin, United Kingdom
Registered: 17 Jan 2005
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Re: Source image orientation scrambling
Posted: 10 May 2008 at 16:58 GMT
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Roy, Remember that the optimizer works by trying to improve whatever the current parameters happen to be. It doesn't start from scratch each time you run it. After applying a template, the optimizer has the best possible start. But, critically, PTGui's Auto Align feature is very dependent on the control point assignment. Some unfortunate points on moving clouds, say, might well result in the optimizer revising the lens parameters drastically in a vain attempt to get everything to align. So you would then have some work to do to get back to the optimum values. The image content might be such that this was impractical. No - once you have loaded in your good parameters via the template, make sure you hang onto them. I don't say that you would never ever optimize the lens parameters after applying a template. You just need to optimize with care and react intelligently to events.
John
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