PTGui Tutorial Part 2 - How to Stitch a Panorama

hi and welcome to part two of this PTGui tutorial series.
in part one we showed you how to take images for a panorama
now we will show you how to use PTGui to stitch those images together.
when you open PTGui
this is what you'll see
just one tab called the Project Assistant and one button to click
once you load your images the rest of the tabs will show up
so let's do that
you start by clicking Load Images and then select the images
and click Open
alternatively you can drag & drop your images right onto the PTGui window
now the images are loaded
and this area is your main workspace
at the top are separate tabs for specific functions
and clicking this Advanced button
reveals a few more tabs
but we will be working with the simple interface for this tutorial
there are also a few helpful tools that you can
access from the toolbar or the tool menu
there's the panorama editor
the control point assistent
and the detail viewer
later i'll go over each of these in detail
for now let's get back to the project assistant
the images right now are out of order
and the two rows of images are lined up side by side
but you don't have to worry about this
below the images are the camera and lens settings which
you can see have been automatically set
this information comes from the exif data
embedded in the JPEG files by the camera
the next step is to align the images
once it finishes the panorama editor will pop-up presenting you with hopefully a
perfectly aligned panorama
so what PTGui did was it analyzed the images, looking for matching
details in the different photos
when it finds these matched details it marks the images with what are called control points
and you can see these in the Control Points tab
from these control point PTGui was able to figure out how the images
overlap
and in this case
figured out that it's a two row panorama
although PTGui may not always be able to find control points for an image
this can happen for instance when there are too few
recognizable details or too many moving subjects within the image
if this does happen
you will just have to add the control points manually
you know when you need to do this because both the project and control
point assistants
will show a warning
you can add the control points for these images in the Control Points tab
here's our image that lacks control points on the left side and on the right
side is one of the images that it overlaps
what you need to do is find a few points within both of these images
that are the same
so you're making pairs
for instance
the corner of this window is in both images
so i'll click here
and then i'll click on the corresponding point
in the other image
once i do that
you'll notice is that the new control point is represented by a numbered marker
it's generally a good rule of thumb
to create at least
four pairs of control points that
cover the overlap area really well
ones the third point is added
PTGui will automatically complete the new control points by using the
information from the existing control points
and in most cases it's quite exact
if the placement is wrong
you can simply click on that point
and drag it
if you need to delete a control point just right click and choose Delete
on a mac with a one button mouse
you can use control click instead of right-clicking
to zoom in and out
use Ctrl and the mouse wheel
or Command and the mouse wheel on a Mac
scrolling is done by dragging with the right mouse button pressed
or control drag
on a Mac
you can use these red arrow buttons to move through the image pairs
more tricks in the Control Points tab
you can click this purple Help button here
now i should have enough control points but
i'll make sure by bringing up the control point assistant
and great it tells me i have enough
back in the Project Assistant tab
i'm told that i need to optimize
the optimizer moves the images in such a way so that the control points
match as closely as possible
every time you make a
change with control points
you should run the optimizer to update the alignment of the images
so i'll run the optimizer now
and then i get a message that tells me the results are very good
so i'll accept them
by clicking OK
now i'll check my control points with the control point table
where i can see information on all the points
every row represents a control point
if i double click a row
i'm brought to that point
the Distance column gives an indication of the quality of alignment
the smaller the distance the better
this control point has a rather large distance
so i want to try to correct it
so now that it's fixed
i'll optimize again
and the results are good
so now's a good time to save the project
this doesn't save the panorama
but rather it's saves the project in its current state
so you can go back to it later
without going through all the previous steps again
now let's check out the panorama
in the panorama editor
here you can move the panorama just by dragging it and you can also rotate it with the
right mouse button
or by control drag on a mac
this makes it useful for straightening horizons
this project in particular was shot with the camera pointing slightly upwards and
the tripod wasn't level
so i'll correct this
first i'll drag the panorama upwards until
all the vertical lines are parallel
and then i rotate the panorama to level it
also you can change the projection of the image
for an architectural scene
like this one you can for example
choose the rectilinear projection
which is also called planar or flat projection
since it's the only protection that preserves straight lines
unfortunately it has a limited field of view
so you'll see stretching in the corners which gets worse the wider the panorama
if the image is more than 120 degrees you need to choose a
different projection
the cylindrical projection is suitable for 360 degree panoramas
the straight lines curve above and below the horizon
but this is the only way to display a 360 degree image
onto a flat surface
an equirectangular protection
is mostly used for a fully spherical panoramas
this projection makes it possible to capture the full spere around the camera
in a single image
but i'll switch back to the rectilinear protection since it looks best for
this particular image
you can also control the field of view
using these sliders
moving the horizontal slider to the left will reduce the horizontal field of view
which will crop the left and right sides of the panorama
the vertical slider works the same way but adjusts the vertical field of view
i'll use this to cut off
the empty part at the bottom
but as you might have noticed
this ends up cutting off the top of the building
this is because the sliders crop the image symmetrically
which always keeps the horizon centered
if you'd like to crop the panorama asymmetrically
you can drag the yellow crop lines from the edges
there are a few other tools here that assist in editing the panorama
the buttons up here let you see blending modes
right now we see the blended panorama
if i click on this button, the Show Seams button
it will show me an unblended version of the image
and the red lines indicate the seams of images
which is useful for identifying possible problems at the seams
clicking on this magnifying glass here opens
the detail viewer
which lets you inspect magnified parts of the panorama
this is useful for finding stitching errors
and here we actually have a blending fault because
the cyclists were moving while the photos were being taken
we can see that the cyclists are in one image
but not in the overlapping image and the seam
runs right through the middle of them
this can be fixed using
the masking feature in the Pro version of PTGui
masking lets you hide certain areas of an image
by using content from
the other overlapping images
so i can fix the blending fault by just removing this biker here
actually the problem isn't completely solved yet
because the fault is right at the seam between four images
but we can fix this by removing another biker
and now it's fixed
to see even more
of what you can do with the mask editor in PTGui Pro
go to our website and check out the masking tutorial
in the Tutorials section
and now to create the panorama
back in the project assistant
i'll click the Create Panorama button which takes me directly to the
Create Panorama tab
here you have a few settings you can customize
for starters you can choose the size of the panorama
you can also choose Set Optimum Size and then
Maximum
which selects the best size
where there won't be any loss of detail
you can also choose from one of these file formats and
further adjust the output file by clicking Settings
if you'll be editing your panorama further
in an image editor like photoshop
you can output each image as a layer
finally
PTGui by default
will save your image using the image or project name
and will place it in the same folder as the original image
but of course you can choose to change the name and the location by clicking
Browse
i'll save the project once more
and then click Create Panorama
and here it is
there was a lot that wasn't covered in this tutorial
but you can always access the help pages in every screen
and if you can't find what you're looking for in the help pages then check
out the support page of ptgui.com
thanks for watching and have fun
and of course happy stitching