Morten Andersen
Posts: 60
Location: Roskilde, Denmark
Registered: 12 Jun 2006
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PTgui problems
Posted: 28 May 2008 at 14:01 GMT
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Hello everybody.
I have recently swithched over to PTgui. I want to create the panoramas as a .psd file for further editing in PS. But when I try that, a transparent area appears in the buttom part of the picture. See it here:
Can anybody explain why this is? And more importantly - how do I avoid it?
Best regards
Morten
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Robert Piontek
Posts: 97
Location: Germany
Registered: 26 Jul 2007
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Re: PTgui problems
Posted: 28 May 2008 at 15:03 GMT
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sorry if this is obvious, but it looks like your camera was not quite pointed down enough, so you did not cover the entire vertical area? did you include a nadir shot? if you tell ptgui to output a 360X180 pano, but your images don't cover all of it, this is what I think would happyen. in any case you either need to patch or crop it out, so it doesn't really matter.
also, it looks like parts of your tripod aren't lining up, which I think means your nodal point is a little off. this could be part of the reason, too.
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Morten Andersen
Posts: 60
Location: Roskilde, Denmark
Registered: 12 Jun 2006
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Re: PTgui problems
Posted: 28 May 2008 at 15:32 GMT
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Hi Robert
I know I still need to ad more control points, and the nodal point is most likely not spot on either. And you are correct - the lense it pointing slightly up - so this is the most obvious reason. And it is actually no problem cloning out the part. What I find curious is that this only happens when stitching as a .psd or a .tiff and not when stitching as a .jpg.
Strange....
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Smooth
Posts: 1472
Location: Australia
Registered: 21 Jul 2004
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Re: PTgui problems
Posted: 28 May 2008 at 15:44 GMT
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Morten Andersen said:
Strange....
Morten,
Strange? Not so...
The reason you see this is because both .tif and .psd save the "alpha" channel which is transparent. If you don't like or want this, flatten the image in Photoshop and whatever is set as the canvas background colour will fill the hole.
Regards, Smooth 
www.smooth360.info
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John Houghton
Posts: 2317
Location: Hitchin, United Kingdom
Registered: 17 Jan 2005
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Re: PTgui problems
Posted: 28 May 2008 at 20:22 GMT
updated: 28 May 2008 at 20:22 GMT
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JPEG files don't support transparency so you cannot generate a panorama with a transparent area. When you output a TIFF file and use the PTGui stitcher, you have the option (via the Settings button) to include the alpha channel that defines the areas that contain no camera image data or you can omit it. It's up to you.
In PSD output, the layer masks do the same job as the alpha channel in rendering areas not occupied by camera data as transparent. If you add a layer filled with black at the bottom of all the layers then you will not see the chequerboard pattern. Everything will in anycase be merged into a single layer without transparency when the file is flattened.
John
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