How to fill black areas of a panorama?

[panhobby]

Hi,

I'm now shooting almost only handheld panoramic pictures. One side
effect is the lack of precision while shooting pictures. Then, it
appears sometime that my pictures are not fully covering the area of
the final image. There some parts at the top or the bottom of the
image that are fully black and without information.

In any case, the approach would go threw the following steps:
1) Fill black areas with other parts of the image
2) Blend the addition from the previous step with the image to produce
the final image.

I wonder what is the best approach/tools to execute the second step?
I did some manual tests with a picture editor (photoshop) but, maybe
because of lack of expertire, I didn't succeeded to get an invisible
blend. It seems the lastest version of photoshop elements provide a
function to fill empty part of an image. As anyone experimented that?
I would think that enblend or a similar tool could be used to do the
merge automatically?

Thanks for your help

PH

[Bruno Postle]

On Tue 04-Jan-2011 at 13:17 -0800, panhobby wrote:
>
>I'm now shooting almost only handheld panoramic pictures. One side
>effect is the lack of precision while shooting pictures. Then, it
>appears sometime that my pictures are not fully covering the area of
>the final image. There some parts at the top or the bottom of the
>image that are fully black and without information.
>

>1) Fill black areas with other parts of the image

Yes, this is how I patch missing areas of sky and ground, you can do
it all in Hugin.

So for a hole in the sky I would select a photo that is already in
the project with a lot of sky and add this again to the project
(you can have the same photo in one project multiple times), but use
the Crop or Mask tab to remove everything but the sky from this
image.

Drag it around in the Preview until it covers the hole, but before
you stitch set the enblend parameters to '-l 29'.

This panorama has the sun (actually my hand shading the sun) and my
shadow removed using this technique, there has been no
post-processing or retouching:
http://www.flickr.com/photos/36383814@N00/5321872706/

..this ought to be a tutorial :-(

--
Bruno

[Lukáš Jirkovský]

http://liquidrescale.wikidot.com/ does a rather good job at filling
smaller areas with missing data.

[dmg]

Maybe this will help?

http://www.youtube.com/watch?v=3ScWu7pG7r0

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--dmg

---
Daniel M. German
http://turingmachine.org

[Emad ud din Btt]

I shoot with 38mm lens so capturing sky is almost impossible. I capture one single image with my fisheye convertor for sky. After optimization of projecty I add sky image. Because at this time hugin allows me to move/ drag sky image independant of all other images. Is there any other way where one can drag/move individual images in fast preview? After that Hugin does a perfect job in blending sky seemlessly. Bruno, thanks for enblend parameter advice. 

2011/1/5 Lukáš Jirkovský <l.jir...@gmail.com>

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Emaad
www.flickr.com/emaad

[kfj]

On 5 Jan., 09:06, Emad ud din Btt <xyzt...@gmail.com> wrote:
> I shoot with 38mm lens so capturing sky is almost impossible. I capture one
> single image with my fisheye convertor for sky. After optimization of
> projecty I add sky image. Because at this time hugin allows me to move/ drag
> sky image independant of all other images. Is there any other way where one
> can drag/move individual images in fast preview? After that Hugin does a
> perfect job in blending sky seemlessly. Bruno, thanks for enblend parameter
> advice.

If the image isn't connected to other images with control points, you
can drag it around freely. You can delete all CPs for an image if you
select it in the images tab and then press 'delete control points'.
This will only remove CPs for this image and not affect the others.

When you fit your fisheye sky to the rest of the image, masking non-
sky portions is a good idea as well - blending errors in clouds or the
blue sky will not be very noticable.

And to fill areas 'intelligenly' you may want to look at the
'resynthesize' gimp plugin:

http://www.logarithmic.net/pfh/resynthesizer

It's a bit hard to figure out, but if you get it to work for you,
sometimes the effect is surprisingly good.

Kay

[panhobby]

I tested the solution described by Bruno. Put an additional image and
move it manually to appropriate location then create the panorama
(using enblend). On my first example, the result is perfect, even
without adjusting the parameter (-I 29). I will do some more tests in
order to validate the approach, then I will take some time to write a
small tutorial. But, sorry, the first version will in French!

Thanks to all of you

PH

[voschix]

Hi Panhobby

I am also a free-hand-panorama-shooter and often have the same problem
that same smaller parts are missing, especially on the end photos of
horizontal panoramas. If you do not have architecture or other
straight lines near the missing bits, then you can use the "curve
bend" function of GIMP during postprocessing. Just cut a rectangular
piece bigger than the missing part, bend the corresponding border of
it to push the black part outwards, and reinsert it.
I have put a short description (unfortunately in Italian, but the
pictures should illustrate the approach) here:
https://docs.google.com/viewer?a=v&pid=explorer&chrome=true&srcid=0BzpxJZ2Uygp_OTg1YTIxYzItZDQ3NC00ZjgyLTg4NWMtZDdlYjVkYTFhMTE4&hl=en&authkey=CJvX57AP


Volker

[voschix]

Hi Panhobby

I am also a free-hand-panorama-shooter and often have the same problem
that same smaller parts are missing, especially on the end photos of
horizontal panoramas. If you do not have architecture or other
straight lines near the missing bits, then you can use the "curve
bend" function of GIMP during postprocessing. Just cut a rectangular
piece bigger than the missing part, bend the corresponding border of
it to push the black part outwards, and reinsert it.
I have put a short description (unfortunately in Italian, but the
pictures should illustrate the approach) here:
https://docs.google.com/viewer?a=v&pid=explorer&chrome=true&srcid=0BzpxJZ2Uygp_OTg1YTIxYzItZDQ3NC00ZjgyLTg4NWMtZDdlYjVkYTFhMTE4&hl=en&authkey=CJvX57AP


Volker

On 4 Gen, 22:17, panhobby <panho...@gmail.com> wrote:

[Emad ud din Btt]

Many thanks Kay for your informative reply. 

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Emaad
www.flickr.com/emaad

[panhobby]

I did some tests with the 'resynthesize' gimp plugin. Actually, you
can use it in two differents ways.
- Smart remove selection on an empty area. Just select the area then
activate the function. It provide interesting results mostly for small
areas.
- The other way is to resynthesize a texture to a selected area. This
is particularly useful for the grass on the ground or part of the sky.
In case the area is not homogeneous enought in terms of texture, it is
better to split it and run the process on each sub-division of the
area. Results may be very good.
In both cases, the result can be almost perfect. Unfortunately, this
is not always the case, there are many situations which provides poor
results.
Obviously, the problem of filling black areas does not have a unique
solution. Depending of each case, on solution can provide better
results than the other. The best is probably to practice and get
experienced in every solutions in order to use the most appropriate
for each image.

Thanks,

PH

[Max]

The easy way to fill black areas is using Inpaint, here is tutorial on vendor
site: http://www.theinpaint.com/inpaint-how-to-fill-black-areas-of-a-panorama.html

[JohnPW]

Bruno (I'm pretty sure it was Bruno) pointed this technique out to me last year and I use it all the time now.

I wasn't aware of the '-l 29' tip though. Can you explain this Bruno? (or someone?)

I have read that it specifies the pyramid blending levels, but I don't know what that means (or what pyramid blending is, what the default number of levels is (beyond, "as many as possible,") or what the implication of using more or fewer leves is :-! )

I assume it helps the blending in some way (reduced smearing perhaps? or to limit the time spent trying to blend what is essentially an un-blendable area?)  Is the parameter used only for the last blend (blending the patches to the rest of the already blended panorama) or is it used to blend the whole panorama at once?

In any case. I have used this technique a lot in partial panoramas (what I mostly shoot.) And I do it without using that parameter (I'll have to experiment.) I usually use it to patch regular areas or surfaces like sky or a wall, but it also works pretty well with more textured surfaces like grass or water (like a lake or ocean surface.) I've even used it for brick walls. It's also handy for moving things slightly to get a nicer composition.

For example, in this image I was able to move the top edge up a bit by patching in sky in the upper L corner and near the upper R corner. To do that, I also moved the edge of the cabin awning (in the UR corner) up several inches and patched the sky below it. If I hadn't done this, cropping to eliminate the missing areas of the image would have made it awkward looking, detracting from an otherwise pretty nice image. (BTW, this isn't the final image (still has some mask and blend problems I've since fixed, but I have been to lazy to update it!)

[JohnPW]

By the way Bruno,

Your technique effectively removes the sun from the image (to reduce the jarring glare of the sun, I assume?)

Might you also take a duplicate image with the sun un-blocked but the shutter down a few stops. I assume this could be used to keep the sun in the image while blending it into the image in a less jarring way. Is this technique used?

Just curious. I rarely do more than partial panoramas so I have no experience with this technique.

On Tuesday, January 4, 2011 4:51:50 PM UTC-6, Bruno Postle wrote:

[Bruno Postle]

On 26 September 2012 03:43, JohnPW <johnpw...@gmail.com> wrote:

> Your technique effectively removes the sun from the image (to reduce the
> jarring glare of the sun, I assume?)
> Might you also take a duplicate image with the sun un-blocked but the
> shutter down a few stops. I assume this could be used to keep the sun in the
> image while blending it into the image in a less jarring way. Is this
> technique used?

Fisheye lenses, my Peleng especially, get a lot of lens flare if the sun is in shot. It's so bad that any of my photos that include the sun are unusable.

--
Bruno

[Bruno Postle]

On 26 September 2012 03:31, JohnPW <johnpw...@gmail.com> wrote:
> Bruno (I'm pretty sure it was Bruno) pointed this technique out to me last
> year and I use it all the time now.
>
> I wasn't aware of the '-l 29' tip though. Can you explain this Bruno? (or
> someone?)
>
> I have read that it specifies the pyramid blending levels, but I don't know
> what that means (or what pyramid blending is, what the default number of
> levels is (beyond, "as many as possible,") or what the implication of using
> more or fewer leves is :-! )

enblend splits each photo up into layers, each representing different levels of detail, and blends them separately before merging back together.

You can think of it as if large scale detail, such as the gradient across the sky, gets blended with a wide 'feathered' seam; and small scale detail gets blended with a zero width seam (it isn't like this internally, but the effect is the same).

The '-l' parameter tells enblend the size of the widest 'feathering', setting '-l 29' effectively says to try and make it as wide as the geometry of the panorama permits, and is a great way of getting a smooth sky across a panorama.

--
Bruno

[JohnPW]

Thanks for both of your responses, Bruno. :-)

[Monkey]

The equivalent of Bruno's "-l 29" enblend tip for multiblend, if anyone is interested, is "--wideblend" :)