360x180° Panorama Tutorial - Pt.3: Stitching in PTGui (1)

Uploaded by elfloz on 15.01.2011

Hello and welcome to part 3 of my little panoramic photography tutorial series.
My name's Florian, and I'm really good at shameless plugs — so please make sure you visit my website
In the first part of this tutorial series I showed you how to *shoot* panoramic images out in the field.
In particular, I was using 3 techniques:
The first one was called "Philpod pitch variation technique"
and I used an 8mm fishey lens on a full frame camera.
Today I will show you how to stitch the images shot with this technique.
In the next tutorial (which will come after this) I will show you how to stitch the images
from the third technique that we did at the time,
which involved an 8mm fisheye lens on a crop camera, but using a tripod.
So we'll have a little bit more editing to do in the next tutorial
where we have to remove the tripod.
This tutorial today will be very straightforward, I'll just show you how to load the images into PTGui,
make a few adjustments here and there,
stitch the images together and we're done.
So this is just a very "no-frills" tutorial to PTGui.
You can do the same stuff with "Hugin" which is a free tool, whereas PTGui costs
a little bit of money, but I just ended up purchasing a license
and I'm very happy with it, so I can really recommand it.
Anyway, let's get started.
So, we'll open up PTGui . . .
here are the images that I exported in the second tutorial from LightRoom
and those four images here
are the ones that we shot with the . . . (ah, I need to grab a different window)
these are the images that we shot with the first technique.
First thing we're going to do is to adjust the crop of the images, as you can see
the image circle projected by the fisheye onto the camera sensor.
What we'll need to do is to tell PTGui what part is the image, and what isn't.
So I'll adjust that crop — and this is now being propagated to all four images automatically.
Another thing that I will do — especially because I shot hand-held —
is to tell the optimizer
to go really "hardcore" and optimize virtually everything,
except the viewpoint.
We don't need to optimize the viewpoint because we shot all the images from the same position.
Well, roughly at least.
That's all we need to do and then we're just going to hit "Align images".
Now, PTGui is going to do its magic. It's trying to find some corresponding points in the images
and then that way it figures out
how those images need to be arranged in order to completely cover the 360° sphere.
So let's have a look at that. That's actually looking pretty good now.
If I go around . . . it is
almost straight . . . Here's another trick on how to see whether it's straight or not:
Just spin your panorama like that.
If it's wobbling a little bit then you know it's not straight.
Another problem that we have, if you look down,
are these flare issues here that come from the Peleng fisheye, which has some serious flare issues,
especially because we have a huge bright sky above us.
There was flaring right along the bottom edge of the images —
you can see that here.
This is what we're going to do in the last tutorial — I will show you
how to edit the vertically down perspective.
Anyway, what we do now is to level the panorama.
The best way to do this is to give PTGui a few extra clues:
We need to tell it what are some vertical lines in the images.
To do that, we have to select the *same* image in *both* of the editor windows — you can see
image 0 in both windows —
and I will selected point
along a same vertical line in the image. You can see, I have added two
"vertical line" control points.
Now, another line that we're going to pick in this image would be this one here.
It's always good to have two lines because if one is not very precise it'll average out
with the other one.
So let me just add some more in the other images . . .
Here's one there, let's use one of those church windows . . .
By the way — the further those points are apart, the more accurate your result would be.
I don't really have very far apart points in these images here . . .
so I'm just going to stick with those.
Where's another one . . . ?
We could just use . . . maybe that . . .
rain pipe here — it's not very clear,
as you can see
there's a bit of camera shake in this image here.
But that's not too bad, especially
because I'm not going to sell this image, this is just a tutorial image.
Okay, so he's another one . . .
Last but not least let's grab one over here, I think there's another rain pipe . . .
They are not too clear vertical lines, but
they will do from now. That's roughly it.
I'm just gonna go back to "Initialize and optimize", now PTGui is going to ask me
"Do you want to optimize the pitch and roll" — which normally it is not doing —
and I'm saying "Yes, of course" because we have vertical control lines
in there, so please do that. And, as you can see, the result is pretty good!
An average control point distance of ca. 3 that's very good,
and we get a green light here.
So let's look at this turned out . . . there we go . . .
and if we turn around
it has stopped wobbling.
Another way of seeing whether your image is straight is to just go along that edge,
keeping your eye on the edge of the frame
and compare the verticals in the image
with the frame of the preview here.
That's looking pretty straight to me.
If I go around here — it's not perfect; I might go back and fiddle with it,
but for the sake of this tutorial that should be enough.
Now, if we look down again we have those flare issues here,
and as I told you earlier, we'll be dealing with those
in another tutorial.
So that's it, we're basically ready to go, just tell PTGui to put it all together.
My lens+camera combination typically gives me around 8200 pixels
but I prefer to use multiples of 2, that's just more beautiful.
(But that's completely random)
I will use TIFF as file format, but I will not use "Blended and layers".
What this option would do is it'll export
not only the blended panoramas but also the original,
warped images along, so you can do some post-processing.
Basically, if you sometimes have problems with objects being inside or outside overlapping areas
you can do some fine tuning with that. There's a pretty good tutorial about this on the
PTGui website as well.
But I'm quite confident in the panoramas, so I'll just select "Blended panorama only".
As my blender I will use the "SmartBlend" plugin.
There's also (if you google it) an installation guide on how to install the
SmartBlend plugin on the Mac. On Windows it's straightforward, but on the Mac it's not,
you'll need to install Wine
and then use the windows executable, but it works pretty well.
As for interpolator I will just choose
the "Lanczos16" which is typically the best one.
All right, so that's it. At this point, all I do is just hit "Create Panorama" and
PTGui is going to start its work, warping the images in high quality,
blending them together and then saving it into a file.
That takes a few minutes, so I'll just pause the recording at this point and come back to you
once the export is done.
All right, so welcome back.
PTGui has finished exporting the image so let's have a look at what we got.
For that, I'll use the free tool "PanoGLView" which is part of the "Hugin" suite.
That's a useful tool to have. It's Mac-only, but on Windows there're enough viewers
as well for panoramic images. I don't know them off the top of my head,
but I'm sure you'll find them.
So . . . let's have a look . . .
That's looking quite nice . . .
If we look down we'll see the flare problem and as I told you, I will show you in the
tutorial after next how to edit this out,
in no time at all.
It's looking good, I don't see any stitching errors here . . .
all the lines nicely join up . . .
I will upload this panorama (when i'm done with it) to "360cities.net"
and I would post a link here in the video comments
so you can have a look at the panorama yourself.
By the way, if you're wondering how I shot the first tutorial —
there is the one camera that I used, and the other camera's there.
I was all alone that day, and it was very cold.
The image is quite noisy because that was shot at ISO 800, and it was hand-held
so there's some . . .
I think that one over here has
quite a bit of camera shake. As you can see, it's not the most pristine quality but
that has nothing to do with the lens or the stitching —
that's more just my shaking hands in the cold.
All right, so that's us done with this image. I will see you in the next tutorial where
I show you how to stitch the images
that we shot on the tripod.
Okay, so thanks for your attention and talk to you soon. Bye!