New to PTGui: problems with correcting stitching errors

[leo.d...@casema.nl]

Hello,

First of all, sorry for my English. I'm Dutch.

This week i made my first attempt to make some 360 (speherical)
panoramas and QTVR's with PTGui.
My setup is: Eos 5d mark2 + Canon 15mm fisheye + a 360 precision pano
head for this combination.
I bracketed (all settings manual off course) -2, 0 and +2 and shot 6
photo's round, 1 up and 1 down.
After this i used enfusegui to make an enfused tiffs of all 8 series
of 3 photo's
So far the easy part..

Learning PTGui was more difficult. Although i am very glad with the
program and it's first results, i find the fine tuning difficult.

First of all, it seems that different attempts with the same series of
Photo's loaded, give different results at the first time i press
"align images" in the Project assistant. Sometimes i need to add more
control points, because 1 image can not be placed, and another time
this wasn't necessary withe the same input images. But that i can fix.
But after giving more control points, the image in the edit panorama
tab is upside down!
I cannot find a way to turn it around again anywhere. That's not
ideal, but still not a major problem.

I already found out what to do about the optimizer warnings: trow away
a number of points in the control point assistant, and run the
optimizer again till it's happy.
But i only see minor difference in the Edit panorama preview. The
images changes and skip a bit (but i can't tell in what way it is
better), but the mistakes in the stitching stay. So what is the
difference, and what is the importance of this judgement by the cp
assistent?
What settings in the optimizer under "globally" would you advice in my
situation (tripod with panohead)? And do i have to disable Yaw, Pitch
and roll for image 0? I find different tips in different tutorials.

That brings me to correcting the mistakes (parallax errors?).
I succeeded in straightening the vertical lines by adding t1 control
points in (the same) image. This works fine: good results with
straight vertical lines!
But i thought that adding a normal control point in 2 different images
could be used for those points where there's no connection between two
images.
So i choose the same points in different images (in the area where the
editor preview shows mistakes). But this never solves the problem! Am
i doing something wrong?
Also shifting 1 image in the edit preview doesn't work: it gives a
mess.
Is the parameter tab an option for this? I have no idea how this
works..

After 2 days playing with the program, and some searching on google,
the best way (and till now the only way) to make corrections is by
masking parts of specific images.
But sometimes the overlap is not enough, or the lines divide too far.

Therefor i create a panorama in layers, and make further adjustments
in Photoshop (i paste parts above the blended layer, and transform
then.
Problem with this is, that i cannot see the final result till i make a
QTVR where the curved lines should be straight again. In Photoshop i
try to make similar lines as existing (connect them), but still in the
final QTVR you can see dents in these parts where i made the
corrections. I worst cases the (more heavy) adjustments (i also had to
"repair" a ceiling with a pattern of stripes) the whole qtvr starts to
wobble when i move around, and the supposed straight lines are curved.
It would be better if could do my repair on images with the "corrected
straight lines". Is it possible to export some kind of cube versions?

The 360 object i photographed weren't the easiest ones: inside with
nearby objects, and lots of lines.
But i also see super results of handheld shot 360's with the
photographer in a crowd.
Almost no mistakes in the stitch, and people write they made it in
real short time! How is that possible, i have a precision panorama-
head and work 2 hours (first the vertical points, and than the
Photoshop repair) for a good result..

I cannot use any of the stitching en blending plugins because i'm a
Mac User (OS 10.6.8). Sorry, but i don't understand that all these
plugins are for Windows for all the Photographers, and designers etc i
know work with Apple..
I red an article about using the Smartblend.exe (it is said to deal
better with Parallax issues?) with Wine on a Mac, but it doesn't work.
Maybe because i use PTGui 9?
Did anyone else succeed in this?

A lot of questions i know.
I really would appreciate it if somebody could help me with some tips.
Thank you!

[John Houghton]

The easy question first! you can rotate the whole panorama in three
ways:
1. Use the two buttons on the right of the Project Assistant tab.
2. Right click & drag the image in the Panorama Editor window.
3. Use the Numerical Transform option (123 button) to apply roll
angle. e.g. 180 to bring the upside down image to right way up.

Treating one image as an anchor by unchecking yaw, pitch and roll
during optimization will generally prevent the panorama image from
turning upside down, as all the images will align with the anchor.
Any image can be selected to be the anchor - not necessarily image 0.

You will get improved alignment if you select Advanced mode and go to
the Optimizer tab. Under Minimize lens distortion, select Heavy +
lens shift. Then click on the Run Optimizer button.

You don't say which 360Precision head you are using. If it's the
Absolute, then you ought not to have any serious problems with
parallax. Stitching errors are more likely to be due to inexpert use
of PTGui. If you ensure that you have points nicely spread along the
overlap areas rather than being bunched in the middle, and you delete
or correct any bad points reported by the Optimizer, you should be
able to get good alignment.

Forget about bracketed images until you have learned how to get a good
stitch from a single exposure set. Having got a good stitch, you can
then make use of the template option to make further stitches easier
and quicker.

Cubic tiles can be output for editing via the Tools->Convert to QTVR/
Cubic option.

Tip: Use "Help->Help for this screen" for guidance at any point in
the processing.

If you cannot sort things out satisfactorily, by all means make a set
of images and your saved project file available and someone here will
find out where the trouble lies.

John