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Tutorial 1
Tutorial 2
Tutorial 3
Tutorial 4 Tutorial 5
Tutorial 5: Notre Dame in perspective
Objectives
In this tutorial
we will show how to:
1) make a vertical
panorama,
2) create
perspective images,
3) understand
imaging.
Open PanoStitcher
Load
As the alternative
to the standard loading utility of "Image Browser", drag-and-drop
from Windows Explorer is used here. Hence close "Load
Images" window.
1) Start Windows
Explorer from the computer Start | Programs | Windows Explorer". Open
the folder "tutorial 4/NotreDame" to show the images:
2) Select
all photos by clicking on the first and then the last image file name while
pressing the [Shift] key.
3) Drag the two
selected images onto PhotoBench.
4) Click on
PhotoBench "Rotate right" button. Click on any image while pressing
[Ctrl] or [Shift] key. All images will rotate 90 degrees clockwise.
5) Arrange the
images by dragging them to their correct locations on PhotoBench.
Fig 1. PhotoBench
containing the raw photo thumbnails
Fig 2. PhotoBench
containing the properly rotated photo thumbnails
Settings...
1) Click on the
Stitch Toolbar "Settings..." button to bring up the "Stitch
settings" dialog box.
2) It is known
that at the focal length (28mm) of the camera used in this example there is
substantial distortion towards the periphery of an image, which needs to be
corrected for stitching. Click on the "Enable" check box to activate
the "Select..." button. Click on the button to pop-up the
"Select Camera Info" dialog box. Select the Camera Info file
"Olympus C-3000 (28mm).txt" and Click OK.
3) Click OK (with
the default stitching "Auto Mode" and "Auto-balance
intensity" should already be selected).
Stitch
1) Click on the
Stitch Toolbar [Stitch] button. PanoStitcher will stitch the image pair to
make the panorama preview.
2) Right-click on
the panorama and choose "Unbend panorama"/"Rotate panorama".
Drag vertically on the panorama so that the long edge of the Notre Dame (closest
to the camera) is leveled and straight.
Fig. 3
Panorama preview: a) raw; b) after unbend/rotate
Blend
1) Click Blend
button to make panorama, which is auto-intensity balanced and auto-cropped with
the default Resolution Ratio of 0.75.
Save
1) Click on File |
Save Project to save the stitching project to the project file
NotreDame2.psp in the "NotreDame" folder. Later you can continue
working by loading this .psp file to PanoStitcher.
2) Right-click in
the panorama window and select "Create 90 degree image" to make the
vertical panorama.
3) With the
vertical panorama window as the active window, right-click
in the vertical panorama window. Select "Save at 100%
resolution" to save the vertical panorama to the name "NotreDame_v.jpg".
Fig. 4
Vertical panorama saved at 50% (screen) resolution
Create
Perspective Images
1) Right-click on
the panorama and select "Select perspective region". Then press
and drag on the panorama to draw a box region. Adjust each side to contain
the structure (Fig. 5).
2) Right-click on
the panorama and select "Create perspective view" to create a
perspective image in a new window
3) Right-click on
the perspective image and select "Rotate left 90" to create the final
perspective image of Fig. 6.
Fig. 5
Select perspective region: OC at center
Fig. 6
Created perspective view (with OC at center). This is equivalent to
the picture taken with a camera with a high-end wide angle lens -- large angular
coverage and distortion free. Now with PanoStitcher you can get the same
result and much more with a regular camera.
Let us now compare
the perspective image of Fig.6 and the panorama image of Fig. 4. Note that
the panorama has the building's straight edges curved, i.e., the scene is
warped, while the perspective image avoids the warping like a picture taken with
a distortion-free camera. A wide panorama is an invert looking world map
-- a world map is a sphere surface which has to be warped to be displayed on a
planar paper! A panorama can display the whole surrounding while a perspective
image can only cover a view span of less than 180 degrees. If the building
is tall such that you have angular span of >150 degrees, non-warping view
actually looks worse due to the divergence towards +-90 degrees.
By design, when taking a picture, the optical center (OC) of a camera's lens
corresponds to the picture's center, where the divergence effect
"originates". With PanoStitcher you can get away with this
limit. Actually the circle in the perspective image box is the OC, which
can be dragged off the default box center (of Fig. 5).
Now let us create
perspective images by :
4) Drag the OC
circle off the center the perspective image box, to the bottom of the building
(see Fig 7)
5) Right-click on
the panorama and select "Create perspective view" to create a
perspective image in a new window
7) Right-click on
the perspective image and select "Rotate left 90" to create the
perspective image of Fig. 9.
Repeat 4)-7) but
with the OC to the top of the building (see Fig. 8) to create the perspective
image of Fig. 10.
You can also drag
the OC to other locations to see what happens.
Fig. 7
Select perspective region: OC at building's bottom
Fig. 8 Select perspective
region: OC at building's top
 
Fig. 9
Created perspective view (with OC at bottom)
Fig. 10 Created perspective view (with OC at top)
Optics
& Imaging
From the
perspective images of Fig. 6/9/10 (which corresponds to the pictures from a
distortion-free camera with wide-angle lens), it can be observed that the
further away an object is from the OC the more stretched out it looks in the
images. You can do an experiment with your own camera: 1) Take a
picture with an object in the center of the view; 2) Take another picture with
the same object at a corner of the view; 3) Compare the shape of the object in
the two pictures.
Also note that
such stretch-out effect is less in the panorama image of Fig. 4.
Hence you might prefer the look of a vertical panorama than its corresponding
wide-angle perspective views, despite the warping.
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