Stitching Blue skies

[Mosley Hardy]

Can someone comment on the best method for stitching blue skies? 

The standard PTGUI stitch seems to sometimes leave uneven color areas.

[Luc Villeneuve]

I would say use a template.

Luc

On 16 juil. 2013, at 08:58, Mosley Hardy wrote:

Can someone comment on the best method for stitching blue skies? 

The standard PTGUI stitch seems to sometimes leave uneven color areas.

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[Mosley Hardy]

Perhaps I should elaborate. In stitching with PTGUI, I have sometimes finished with a blue sky in which the color seems to blend unevenly from one image to the next. I know that skies are always challenging to blend and am wondering if there are ways to improve that result, such as enblend or some other plugin.

[UtahBob]

On Tuesday, July 16, 2013 9:22:41 AM UTC-4, Mosley Hardy wrote:

Perhaps I should elaborate. In stitching with PTGUI, I have sometimes finished with a blue sky in which the color seems to blend unevenly from one image to the next. I know that skies are always challenging to blend and am wondering if there are ways to improve that result, such as enblend or some other plugin.

Two ways that I accomplish what you want.  First is to go to the Exposure Tab and then Settings for Auto Exposure and Color Adjustment and select Enabled (full) for Optimize Exposure.  Vignetting can also cause issues and if you can fix that before you load the images into PTGui so much the better.  The Second method is to go to the Image Parameters Tab and enter a correction value in the Exp offset column.  -1.0 decreases the exposure for the image by a full step.  You don't need much in this box to make a difference - sometimes very small values.  If you have the pano editor window open at the same time you can see the changes in real time if you are in full blend mode. I found that Enblend or Smartblend did not fix these problems.  If you have uneven exposure within the image due to your camera - i.e. the right side is lighter than the left - that's a bit more difficult.  I don't have that issue but if I recall the best method is to fix it before loading images into PTGui by using methods similar to fixing vignetting.  If that's your problem, there is a thread somewhere here that discusses it.

Bob

[Mosley Hardy]

Thanks Bob.

 It's not exposure (I shoot manual-everything) or vignetting. AutoPano can stitch the sky perfectly but it doesn't import PTG control points properly, so that's not a workable solution either.I'll have to post an example this evening. 

[Luc Villeneuve]

What body/lens you use? 6+2? Do you tilt down your camera for your shots

On 16 juil. 2013, at 10:37, Mosley Hardy wrote:

Thanks Bob.

 It's not exposure (I shoot manual-everything) or vignetting. AutoPano can stitch the sky perfectly but it doesn't import PTG control points properly, so that's not a workable solution either.I'll have to post an example this evening. 

[Mosley Hardy]

Nikon D800e/Nikkor 16mm/ Nodal Ninja RS-1/NN Nadir adapter.

I shoot 6 around at -10 degrees, zenith at +65 and a couple of Nadirs at -90

[Luc Villeneuve]

The reason why I ask is if your lens does vigneting and you are using a larger area of the zenith, the vigneting could be the culprit. If you tilt down your body, you probably use more pixels from the zenith.

Am I wrong?

Luc

[Mosley Hardy]

I haven't seen that before but I suppose it's possible. 

I'll try running vignette correction in ACR first and then stitching those files to see if the issue changes.

[Erik Krause]

Am 16.07.2013 21:23, schrieb Mosley Hardy:
> I'll try running vignette correction in ACR first and then stitching those
> files to see if the issue changes.

Don't you have the pro version? If you have, no need to do that. PTGui
pro vignetting correction is far better, since it determines vignetting
from the overlap. See http://www.ptgui.com/examples/vigntutorial.html
for details.

--
Erik Krause
http://www.erik-krause.de

[Mosley Hardy]

I do have the pro version and I have been using the optimize function prior to creating my panoramas. 

I'll just have to post a finished pano tonight so that everyone can see what I'm seeing.

I'd just use AutoPano Giga for the final stitch of projects that show this issue if it would import the PTG project properly. Unfortunately the current version of APG doesn't seem to retain all of the control points in an imported PTG project.

[PTGui Support]

Hi Mosley,

If you can please post the source images and project file as well, so we
can see what the problem might be.

Also if you used any vignetting correction outside PTGui, try to do
without that correction and see if that changes anything. In particular
if the lens is mounted off-center and your RAW converter is attempting
to correct vignetting relative to the image center (instead of lens
center), this introduces a new kind of vignetting which can no longer be
eliminated. OTOH PTGui is able to correct off center vignetting perfectly.

Kind regards,

New House Internet Services BV
Joost Nieuwenhuijse

-----------------------------------------------
PTGui - Photo Stitching Software

www.ptgui.com
For support see: http://www.ptgui.com/faq/
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[Erik Krause]

Am 16.07.2013 21:50, schrieb Mosley Hardy:

> I do have the pro version and I have been using the optimize function prior
> to creating my panoramas.

Vignetting correction works on radially symmetric vignetting only. If
there is light falloff due to shutter speed variations it won't help.

> I'll just have to post a finished pano tonight so that everyone can see
> what I'm seeing.

That would be best, indeed.

> I'd just use AutoPano Giga for the final stitch of projects that show this
> issue if it would import the PTG project properly.

APG uses the smartblend algorithm. So perhaps you're lucky if you use
smartblend as blender.

[Tom]

When I got  a new camera (Lumix FZ200) I suddendly had big trouble  with vignetting, particularly in the sky parts of the panoramas.
Seemed that the vignetting is located off-centre, and in therefore vignetting correction didn't work well in PTGUI pro.

It took me quite a while to develop a new work-flow which really works:

- shoot RAW images rather than jpg

- Vignetting correction with DxO Optics pro (it has the correction parameters for the FZ200 - they have really measured it)

- PTGUI pro: Project/align to grid

- "Align images" - Button

- Move misplaced images to the approximate position. This can be a bit tedious. Interestingly, misplacement of a sky image may affect the brightness significantly - but this will easily be corrected in the next step

- Exposure/HDR: Settings - Optimize Exposure: Enabled   (fine tune only), this will tune the Exposure Offsets in  Image Parameters (Bob has already recommended this)

- Fine tuning: you can modify the exposure Offset manually in the Image parameter Tab.

Panorama with the workflow as described above: http://www.gigapan.com/gigapans/133503

old workflow - badly corrected vignetting and exposure:  http://www.gigapan.com/gigapans/116019

[panox]

http://youtu.be/pA6QtqVSE00

If you mean stitching without control-points..

Harald

Am Dienstag, 16. Juli 2013 14:58:01 UTC+2 schrieb Mosley Hardy:

[Mosley Hardy]

I've crated a dropbox folder at this link:  

https://www.dropbox.com/sh/z46dcevoxy76b11/nyVX2NHrmv

It contains a zip archive of the source files, the .pts file and a layered TIFF. 

The layered TIFF contains a stitch from PTGUI as well as a stitch of the same .pts imported into autopano. There are 2 additional layers of annotation.

[UtahBob]

Mosley,  I was able to successfully download the files.  The problem areas are caused by the PTGui trying to blend areas of the sky that have changed from one shot to another.  I ran into this two weeks ago.  If you look at image 0 and image 4 you can see that the sky in that problem area in the final stitch has changed from clear to clouds.  The blender is only blending in the overlap area so you end up with this blending of clear sky and clouds.  I don't use autopano but from Joost's comment if that uses smartblend to do the blending then it will place the seams in such a manner that it avoids blending clear sky and clouds.  

I get around this by carefully masking either the clear sky and the clouds until I have something acceptable and then do some fixing in photoshop if needed. If you can identify the seams that autopano uses - you might be able to do that if you can get a layered tiff with each source image masked - then you could try to duplicate that in PTGui using the masking tab.  To get it to work, I sometimes have to both red and green mask at the same time.  If you have the pano editor window open you can see it in real time.

I'm hoping someone has some other insights on how to best fix this as the masking helps it but it's not perfect.  I'm on a mac right now and I don't have smartblend so I can't run it.  From my understanding, green and red masking is picked up by the PTGui blender but only red masks are passed to other blenders.

I've got to get me one of these cameras!  One thing I noticed is that there is a lot of CA in the original images.  I can't open the NEF on this mac but I think you should definitely feed PTGui some corrected TIF files either from ACR, etc.  Don't know if dcraw is creating some of that?

Bob

[Michel Thoby]

Le 16 juil. 2013 à 22:30, Erik Krause a écrit :

I'd just use AutoPano Giga for the final stitch of projects that show this

issue if it would import the PTG project properly.

APG uses the smartblend algorithm. So perhaps you're lucky if you use smartblend as blender.

-- 
Erik Krause

IFAIK AutoPano Giga doesn't readily support Smartblend anymore. If I remember correctly, the move happened three years ago (withAPG  2.5.0 Alpha 1) when Kolor introduced Cortex (the new rendering engine) that they created from scratch.

BTW You may read http://tinyurl.com/l3mj3ue to check that "Multiband" blending has taken the place formerly held by the "Smart" option. While I'm not certain that this page describes the latest APG 3.0.6 version, it is IMO fully relevant to the present discussion topic i.e. "Stitching Blue skies".

Michel Thoby

[John Houghton]

On Wednesday, July 17, 2013 3:18:53 AM UTC+1, UtahBob wrote:

I'm hoping someone has some other insights on how to best fix this as the masking helps it but it's not perfect.  I'm on a mac right now and I don't have smartblend so I can't run it. 

I did a PTGui stitch with Smartblend and got this result: http://ge.tt/2iuCY0m/v/0?c .  Again, not quite perfect, but some masking in the sky would probably help.  (I used tiff files generated with ACR rather than NEF, but had some weird effects in the images on my Windows 8 system.  I'm not sure what was happening, but I dealt with it by making copies with IrfanView).

John

[Mosley Hardy]

Thanks Bob. I'll experiment with the masking.

Yes, the Nikkor 16mm tends to develop CA when the sun is in the shot. It's a nice sharp lens otherwise though and ACR or DxO can usually take care of the CA, so it's not a deal breaker.

[Mosley Hardy]

Thanks John. That does look better. It's a pity that SmartBlend isn't available for mac. I suppose I could install PTG under parallels, but that would be a pain

[Karel Gillissen]

Smartblend runs very well on a Mac under Wine, so PTGui can run natively.

I posted a small tutorial on the panotools wiki how to install smartblend on a Mac:

http://wiki.panotools.org/Smartblend_on_Mac

Cheers,

Karel

http://360vr.nl

[Klaus Esser]

Hi!

APG´s switch to Cortex has at least two advantages: 

1) it´s MUCH faster even with very big panos than smartblend.

2) it´s "cleaner". 

With smartblend i often had an issue seeing "smeared" areas in the rendering where a bit too much overlap existed.

This is gone!

I now use a motorized/programmable head writing xml-files for positioning. This and APG´s version of multiblend makes everything  better.

Two examples:

http://360impressions.de/KBogen413/ 700 mpx and 4 Gpx, 35mm and 85mm

http://www.360impressions.de/KLapheckFull/ 700 mpx indoors 35mm

both done with APG 3.0.5.

Especially shooting spheres containing blue skies with longer lenses - like 35mm and 85mm - works as fast and effortless as using a fisheye when you can use xml for positioning.

best, Klaus