HDR Stitching with viewpoint correction of the nadir image - not working!

[Keith]

Hi,

I am very familiar with sliding in the nadir image using viewpoint correction. This is where you've moved the tripod off the spot where you shot the normal panorama (for me that's 6 images in a circle and one upwards). Off one side you shoot the ground where the tripod was and take another photo. The technique is detailed on the PTGUI website. IT's so you can cover up the 'hole' underneath the tripod.

Now, I'm trying to do the same thing, but with a HDR workflow. 

I was merging all the bracketed images into a set of single HDR images before going into PTGUI. That's 8 for me. I would then stitch the 6 images in a circle and the one pointing upwards (7 in total). Leaving the 8th for the viewpoint correciton. But what I'm finding is PTGUI can't find any control points with 32-bit HDR radiance images, so I have to set all the control points manually. Then the viewpoint correction technique works for the nadir image (the 8th). This is a bit slow to say the least!

So... I'm trying to load all of the separate bracketed images into PTGI at the beginning. Leaving out the bracketed set for the nadir. PTGUI does a great job of finding control points for these and the resulting pano will output a HDR 32-bit file with no problem, except for the black hole where the tripod was.

What I don't appear to be able to do is slide in the nadir image as before. I drop in the nadir set of bracketed images into PTGUI, I set control points as I am used to, but when I optimise (with viewpoint correction ticked in the optimiser advanced mode) the nadir images go all over the place and ruin the pano.

So, does anyone have any experience of this workflow? I thought PTGUI would treat all bracketed images as one, so to speak! Is there some special consideration when setting control; points in a set of HDR images?

Shouldn't this 'that as one' also apply to masking?!

Many thanks,

Keith

www/fachwen.org

[Keith]

I've been looking around the help files and I notice in the image parameters you can explicitly set and link groups of bracketed images together, and all the control points that PTGui creates its self are on the 1st image of the set of bracketed images. So when I add the nair set of bracketed images I'll check they are linked properly, and only add control points to the 1st image in each group. Might work?

[PTGui Support]

Hi Keith,

Yes it should work.

If you add the nadir images later (as you do) then they will not be
linked automatically. Enable the Link checkboxes in the Image Parameters
tab for the nadir images except the first one of the bracketed set.

But try this:

- load all images (including nadir) at once
- go to Mask tab and mask out the entire nadir image except for the part
that is flat (the floor). This ensures that control points are only
generated there
- then run Align Images. You'll get a not so good aligned panorama
initially (due to the parallax).
- Go to the Optimizer tab, enable viewpoint correction for the nadir and
re-optimize.

Kind regards,

New House Internet Services BV
Joost Nieuwenhuijse

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

www.ptgui.com
For support see: http://www.ptgui.com/faq/
-----------------------------------------------

[Keith]

Thanks Jost, that workflow sounds amazing! So much quicker!! Brilliant, can't wait to try it this evening :-)

When you say mask the nadir, should I mask out just the first image in the linked set of nadir images? 

Or do I have to mask out each one? (I have 7 btw, as my shiny new Olympus e-m1 can shoot a HDR of 7 images with 2ev gaps in-beween... with a single press of the shutter, marvellous :-) ) 

Many thanks,

Keith

[Keith]

Ha, answering my own query here!! Just tried this workflow, partially. 

The masking only needs to be done on the 1st image in the nadir set, which is great.

I have to go out now, so can't try the next bit. But will it be the same with "enable viewpoint correction for the nadir " - do I only need to check the 1st image in the set, or them all?

Many thanks,

Keith

[Keith]

All working fine here now. Thanks again, very streamlined workflow. Should save me a lot of time :-)

[Shoreline Pixels]

Keith,

Thanks for posting this question.  If this works, you'll have saved me a bunch of wasted time too.

Nice website, btw.  How did you manage to embed the pano, without using an external link elsewhere?

Peter

[Keith]

On Friday, 4 December 2015 12:58:11 UTC, Shoreline Pixels wrote:

Keith,

How did you manage to embed the pano, without using an external link elsewhere?

Hi Peter, thanks for the compliment. Just getting back into Pano photography after a bit of a break. I embedded the pano in the webpage with a tiny bit of code, I was helped by the great people over on the Pano2VR forum, which is the tool I use to wrap the equirectangular images up with skins, etc, to post on-line.

Here it is:

<iframe src="http://www.fachwen.org/panos/000000-home-screen/index.html" name="panorama" width="400" height="200" scrolling="no" marginheight="0" marginwidth="0" frameborder="0" style="float:left; margin-left:0px" allowfullscreen="true" webkitallowfullscreen="true" mozallowfullscreen="true"></iframe><p></p>

[Shoreline Pixels]

Thanks Keith,

I'll give this a try.

Peter

[create...@gmail.com]

Hi Keith,

Ever so slightly off topic but just wondering how you get such perfect floor nadir stitching? I have just visited you very nice website and noticed that the wooden floor stitch on the cafe panorama is as good as perfect! No matter how careful I am with making sure I get the angle as close as possible directly above the tripod point the stitch is always slightly out? I add manual control points but i can never get it to line up in a clean stitch.

Many thanks,

Rich.

[John Houghton]

On Monday, January 4, 2016 at 8:41:41 PM UTC, create...@gmail.com wrote:

 No matter how careful I am with making sure I get the angle as close as possible directly above the tripod point the stitch is always slightly out? I add manual control points but i can never get it to line up in a clean stitch.

Rich, You do not  need to position the camera directly above the tripod point when taking the nadir shot.  Viewpoint correction enables the image to be correctly aligned even when the camera is offset by as much as one metre (for flat floors, that is).  If you care to upload a set of your images somewhere (half size jpegs are good enough), I'm sure that any problems cane be quickly sorted out.

John

[twalp]

Joost,

In the steps after "But try this:", did you leave out "Align Images" and "manually enter control points in nadir shot"?

[PTGui Support]

No, ideally the below should work. The masking trick works because the
control point generator will stay away from the (red) maked parts of the
images. So if you mask out the nadir image entirely, except for the flat
floor, PTGui would only add control points on the floor.

Of course it's possible that the control point generator fails to find
any points, so yes, in that case you'd need to manually enter control
points.

Joost

> www.ptgui.com <http://www.ptgui.com>

> For support see: http://www.ptgui.com/faq/
> -----------------------------------------------
>
> On 14/11/2015 00:27, Keith wrote:
> > I've been looking around the help files and I notice in the image
> parameters you can explicitly set and link groups of bracketed
> images together, and all the control points that PTGui creates its
> self are on the 1st image of the set of bracketed images. So when I
> add the nair set of bracketed images I'll check they are linked
> properly, and only add control points to the 1st image in each
> group. Might work?
> >
>

> --
> Many people are reading this forum via email and get every post
> delivered to their inbox. To limit the amount of data please do not add
> attachments or images to your posts; instead upload your files at a file
> sharing site (for example http://ge.tt/ ) and include a link in your
> message.
> ---
> You received this message because you are subscribed to the Google
> Groups "PTGui Support" group.
> To unsubscribe from this group and stop receiving emails from it, send
> an email to ptgui+un...@googlegroups.com
> <mailto:ptgui+un...@googlegroups.com>.
> To post to this group, send email to pt...@googlegroups.com
> <mailto:pt...@googlegroups.com>.
> Visit this group at https://groups.google.com/group/ptgui.
> To view this discussion on the web visit
> https://groups.google.com/d/msgid/ptgui/652c5090-4fd4-4274-8bf7-e87ca237a895%40googlegroups.com
> <https://groups.google.com/d/msgid/ptgui/652c5090-4fd4-4274-8bf7-e87ca237a895%40googlegroups.com?utm_medium=email&utm_source=footer>.
> For more options, visit https://groups.google.com/d/optout.