Gandalf2003
Posts: 21
Location: Paris, France
Registered: 28 Nov 2007
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Tripod Shadows
Posted: 19 Sep 2008 at 7:44 GMT
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Hi all,
You always produce fantastic panos and I was wondering how do you deal with dropping shadows like these ?
Have a good day !
Gandalf
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John Willetts
Posts: 49
Location: Bath, United Kingdom
Registered: 13 Mar 2008
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Re: Tripod Shadows
Posted: 19 Sep 2008 at 8:34 GMT
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Only one way, Gandalf.
An hour's careful work on Photoshop.
Sorry,
John
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John Houghton
Posts: 2317
Location: Hitchin, United Kingdom
Registered: 17 Jan 2005
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Re: Tripod Shadows
Posted: 19 Sep 2008 at 9:08 GMT
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Shift the tripod sideways at right-angles to the direction of the light. Take an oblique shot and stitch in with PTGui's Viewpoint Correction feature. It's best to mask out the unwanted shadows from the horizontal images using alphachannel masks, to guarantee that the patching shot gets used in those areas. With multiple light sources, you might need more than one extra nadir shot.
John
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Henri Smeets
Posts: 63
Location: Amsterdam, Netherlands
Registered: 28 Nov 2006
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Re: Tripod Shadows
Posted: 19 Sep 2008 at 9:12 GMT
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2 minutes PhotoShop, healing brush!
This was done the quick way, a little more attention to existing shadows and patterns and the result can look even better.
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John Willetts
Posts: 49
Location: Bath, United Kingdom
Registered: 13 Mar 2008
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Re: Tripod Shadows
Posted: 19 Sep 2008 at 9:52 GMT
updated: 19 Sep 2008 at 10:06 GMT
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Re: John's reply
Too complicated
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John Willetts
Posts: 49
Location: Bath, United Kingdom
Registered: 13 Mar 2008
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Re: Tripod Shadows
Posted: 19 Sep 2008 at 9:53 GMT
updated: 19 Sep 2008 at 10:08 GMT
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Re: Henri's reply
Good, but do you want to be a perfectionist? I can see the joins.
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Henri Smeets
Posts: 63
Location: Amsterdam, Netherlands
Registered: 28 Nov 2006
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Re: Tripod Shadows
Posted: 19 Sep 2008 at 10:08 GMT
updated: 19 Sep 2008 at 10:10 GMT
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It all depends on the kind of subject and how the final panorama will be displayed. For virtual tours of a hotel the carpet is not very important. In a church however the floor should be almost perfect imho. For print you should be really carefull with all cloning tools, the print pattern can reveal unwanted editing 'scars'.
John's way is very accurate but can be time consuming on the photography end, a handheld shot can cost you extra photoshop time. Take your pick 
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John Willetts
Posts: 49
Location: Bath, United Kingdom
Registered: 13 Mar 2008
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Re: Tripod Shadows
Posted: 19 Sep 2008 at 13:21 GMT
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Quite agree, Henry.
In fact, I'd go a stage further. If the nadir isn't particularly important or interesting, I just limit the angle of view.
At last we have no wind and sunshine in England - so I'm off out to take some pictures.
John
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DennisS
Posts: 56
Location: Los Anglels, United States
Registered: 1 Sep 2007
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Re: Tripod Shadows
Posted: 19 Sep 2008 at 14:45 GMT
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Here is an example of lots of tripod shadows. The room was very small and there were several light sources. I followed John's very excellent tutorial on alpha channel masks. www.johnhpanos.com/alphatut.htm If you have not visited his site yet, you should. Highly recommended reading
I took 1 nadar shot and two patch shots (using an offset camera bracket) then brought all the images into PTGui and set the control points. I then went back and applied an alpha channel mask using Photoshop. Since the control points were set, I could mask out whatever I wanted and the images still lined up. PTGui 8 has a very nice feature that if a picture changes, it automatically reloads it. You can see the results of applying an alpha channel very quickly. The Pano preview screen shows you what the blended pano will look like in real time. Very nice feature. During the final stitching, PTGui handles the blending. No need to do any blending in Photoshop prior to stitching. Since the carpet is dirty, I could fudge a little. I did need to touch up the stitched image a little bit prior to creating the final .mov file. Although not perfect, the result is acceptable.
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Tri3
Posts: 44
Location: Austin, Texas, United States
Registered: 14 Sep 2008
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Re: Tripod Shadows
Posted: 19 Sep 2008 at 16:34 GMT
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Nice little article. Thanks for sharing.
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Gandalf2003
Posts: 21
Location: Paris, France
Registered: 28 Nov 2007
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Re: Tripod Shadows
Posted: 19 Sep 2008 at 16:55 GMT
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Thank you very much for your precious advices.
I tried John's H. technique by using viewpoint correction and it works wonderfully by hiding shadows on vertical shots with alpha masking like he said.
Thanks again for sharing and taking the time to explain your methods !
Regards, Gandalf
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klaus mayer
Posts: 87
Location: Australia
Registered: 15 Jan 2008
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Re: Tripod Shadows
Posted: 21 Sep 2008 at 22:55 GMT
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Not sure if this also works with PTGui and PS but when working with Hugin and Gimp you can add the alpha channel mask before loading the pics and adding control points as long as you save colour values for transparent areas.
Hugin does not show the mask in the control point window which allows you to place control points in areas that will disappear during blending. Only the preview window shows which areas areas are masked out.
This saves you time switching between programs and reloading pics.
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DennisS
Posts: 56
Location: Los Anglels, United States
Registered: 1 Sep 2007
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Re: Tripod Shadows
Posted: 22 Sep 2008 at 4:55 GMT
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klaus mayer said: This saves you time switching between programs and reloading pics.
Klaus,
With PTGui version 8 panorama preview window open, as soon as you save a change to an image using Photoshop, PTGui senses that the image on disk has changed and automatically reloads the image, then updates the preview screen. I have the preview screen open on one monitor, PS open in another. Changes to an image in PS are updated in Ptgui as soon (or after a few seconds) after the image is saved in PS. No need to switch back and forth and reload in PTGui. You can see in almost real time the effects of your edits in Photoshop.
I am not aware of a feature in PTGui that allows you to show the area under an alpha channel mask. Any of the PTGui pros want to answer this one?
Dennis
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John Willetts
Posts: 49
Location: Bath, United Kingdom
Registered: 13 Mar 2008
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Re: Tripod Shadows
Posted: 22 Sep 2008 at 9:02 GMT
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Re DenisS' posting.
A useful technique for carpets. But how do you do it with a fisheye on the end of a hand-held pole?
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DennisS
Posts: 56
Location: Los Anglels, United States
Registered: 1 Sep 2007
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Re: Tripod Shadows
Posted: 22 Sep 2008 at 12:32 GMT
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John Willetts said: A useful technique for carpets. But how do you do it with a fisheye on the end of a hand-held pole?
John,
The objective is to take enough pictures of the Nadar shot in order to have all sections with no tripod (or pole) shadows. The camera/lens used does not matter. The technique is the same.
You would take your first shot, change position so your shadow now falls on a completly different area, then take the second shot. I use this for all my panos. Carpet, grass, stone pavement, etc., it is all the same. I have not tried using a pole. Others here will be able to shed light the technique. I would imagine you would still need to reposition the camera on the end of the pole at some point in order to get a clear Nadar shot.
Dennis
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