John Houghton
Posts: 2170
Location: Hitchin, United Kingdom
Registered: 17 Jan 2005
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PTGui Viewpoint optimization
Posted: 7 May 2008 at 7:24 GMT
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When using the viewpoint option on a nadir image in PTGui Pro, the optimizer doesn't always find the optimum position straight off, even after doing a normal optimization first to get it into roughly the right position, or positioning it manually in the Panorama Editor window. You might only get a disappointing average cp distance of 10 and a maximum of 20, say. Nudging the image about manually and repeating the optimization can eventually get it out of this rut and into the optimum position, but I've found a quicker and more reliable solution. What you do is apply pitch -90 with the numerical transform option to bring the nadir to the centre of the output area, and then repeat the optimization. It then seems very much more likely to find the optimum position. When the panorama is flipped back into its normal position by applying pitch +90, the good optimization is still obtained. It's also a lot easier to drag the image into approximately the right position when the nadir is shifted to the centre.
John
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Smooth
Posts: 1455
Location: Australia
Registered: 21 Jul 2004
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Hamish Tear
Posts: 37
Location: Jackson, United States
Registered: 8 Nov 2007
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Re: PTGui Viewpoint optimization
Posted: 14 May 2008 at 4:05 GMT
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John,
I had a bad experience with a zenith shot recently - but much more extreme than your description. PTGui seemed to treat it like a 'seventh' image in my circle of six, rather than putting it into the zenith position at all. This was of course first obvious in the panorama editor window. Have you ever heard of such an 'extreme' non-placement of the zenith (or nadir) images?
I'll try it again and use your techniques described above to try to drag it into place and then re-optimize.
Hamish.
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Hans Nyberg
Posts: 752
Location: Denmark
Registered: 28 Aug 2005
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Re: PTGui Viewpoint optimization
Posted: 14 May 2008 at 7:30 GMT
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Hamish Tear said: John,
I had a bad experience with a zenith shot recently - but much more extreme than your description. PTGui seemed to treat it like a 'seventh' image in my circle of six, rather than putting it into the zenith position at all. This was of course first obvious in the panorama editor window. Have you ever heard of such an 'extreme' non-placement of the zenith (or nadir) images?
I'll try it again and use your techniques described above to try to drag it into place and then re-optimize.
Hamish.
Are you sure your zenith did have controlpoints. It is very common that you do not get autocontrolpoints for zenith if the subject is just sky or a white ceiling. You need to ad manual controlpoints or perhaps just position th image manually.
You should get a warning about on the Project assistant.
Hans
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John Houghton
Posts: 2170
Location: Hitchin, United Kingdom
Registered: 17 Jan 2005
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Re: PTGui Viewpoint optimization
Posted: 14 May 2008 at 7:43 GMT
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Hamish, I've seen PTGui (and the Panorama Tools optimizer) produce all sorts of bizarre results. Most commonly this happens when starting from scratch, with the images all assigned the same y,p,r values by default. Generally, you have a pretty good idea of what the values should be (and also the lens parameters) from previous projects. To me it seems perverse to deliberately withhold all this useful information from PTGui and then fret and fume when the optimizer fails to deliver the goods. I always either apply a template to initialize the project with sane values, or quickly enter rough yaw and pitch values on the image parameters tab, making use of Fill Yaw and updating values by column selections. When this is done, I find bizarre results are very rare.
John
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