Tutorial 5: Skyscraper

Objectives 

1) load images to PhotoBench from Windows Explorer as an alternative to the "Load Images" window,

2) transform the panorama using the "Unbend panorama"/"Rotate panorama" features to make the pyramid building symmetrical in the panorama,

3) manually adjust brightness/contrast of PhotoBench images to handle extreme exposure variations,

4) make a vertical panorama,

5) save a high-resolution master panorama for screen saver or printing and derive a lower-resolution version for web publishing,

6) print the panorama using the visual printing utility.

Take the photos

1) Zoom the lens out to the base focal length of 28mm and set the camera to auto-exposure.  Note if the exposure had been fixed, it would have been impossible to avoid over-exposure and under-exposure for all the four images due to extreme contrast variation.

2) Take overlapping photos handheld while tilting the camera upward.  Try to stay on one spot and keep the camera at the same spatial location as you shoot upwards to minimize the parallax effect.  The overlap is around 30%. 

Transfer photos from camera to computer

Load the photos from the camera's memory to the directory in the computer named "skyscraper" (the file names are changed to skyscraper00x.jpg for demo convenience).

Open PanoStitcher

 Following PanoGuide, each step of the stitching process is described in the following:

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 3/skyscraper" 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 four 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. 

6) Optionally, click Adjust Overlap button on the PhotoBench to pop-up "Set Image Pair Overlap" window.  Drag each overlying image to roughly register its overlap with its left neighbor.  Then click on top-right [x] to hide the window.  

Fig 1. PhotoBench containing the raw 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) The default stitching "Auto Mode" should already be selected. 

4) Check "Auto-balance intensity".

5) Click OK.

Stitch

1) Click on the Stitch Toolbar [Stitch] button.  PanoStitcher will stitch all image pairs to make the panorama preview. 

2) Inspect the panorama preview. All images are properly registered, but the building seems "crooked".  Right-click on the panorama and choose "Unbend panorama".  Drag vertically on the panorama to make the pyramid more symmetrical. Then pop-up the floating menu again to choose "Rotate panorama".  Drag vertically on the panorama to level the pyramid. 

Fig. 2a  Panorama preview

Fig. 2b  Panorama preview: unbent/rotated

Blend

1) Change Resolution Ratio from default .75 to .50 to speed up blending process.  This ratio corresponds to a panorama size of 637 x 302 pixels. 

2) Click Blend button to make the auto-intensity balanced panorama (auto-cropped).. 

Inspecting Fig. 3, the intensity transition is great but the ground level is too dark.  The reason is that the scene has extreme brightness variations and the auto-balancing's job is to make smooth intensity transitions.  But you might care more about the visibility of all scene areas.  You can exert your preference using the manual intensity balancing tool.

Fig. 3  Panorama: with auto-intensity balancing

3) Click "Settings...". Uncheck "Auto-balance intensity". 

4) Right-click on PhotoBench image #2 to pop-up the floating menu. Choose "Adjust Brightness/Contrast".  The Brightness/Contrast menu shows up.  Move the Brightness and Gamma the sliders to the right and the Contrast slider to the left to promote the overall brightness while reducing  the contrast.  Click on image #3 to connect it to the "Brightness/Contrast" menu and adjust. Repeat the process with image #4.  No adjustment is made for image #1.  The settings of all four images are shown below.  The goal is to provide good visibility of features in each image and in the meantime to try to balance the intensities in each pair's overlap area.  The effect on the images  is shown in Fig. 5b. 

Fig. 4  Manual-intensity adjustment settings of the four PhotoBench images. 

4) Click Blend.

5) Repeat Step 3), experimenting with settings, and 4) until a satisfactory result is achieved.  Then increase the Resolution Ratio to 75% to make the master panorama.

Now the panorama is made!

Fig. 6  Panorama with manual-intensity adjustments

Edit

1) Right-click on the panorama and choose "Select crop region".  Fine-tune the auto-selected crop region by moving the region's each side. Right-click on the panorama and choose "Crop".

2) Right-click in the panorama window and select "Create 90 degree image" to make the vertical panorama.

Save

7) Click on File | Save Project  to save the stitching project to the project file skyscraper2.psp in the "skyscraper" folder.  Later you can continue working by loading this .psp file to PanoStitcher.

1) Right-click in the vertical panorama window.  Select "Save at 100% resolution" to save the vertical panorama to the name "pano_skyscraper_v.tif" which is uncompressed.  This is the master panorama for future use.

3) Click on Main Toolbar "Print" button to bring up the visual printing utility.  Set page Orientation to Portrait in Setup | "Page Setup" dialog box.  

Right click in the panorama window to pop-up the print floating menu and choose "Fit 2x1 Pages".  Click on Print to print the panorama to two 8"x11"pages. 

* The two printed pages will need to be taped or glued, and will have visible seams. A better way is to tape or glue two blank papers together before printing, or to buy panorama photo paper (8"x22"). Then in Print setting, choose the proper "paper size" in "Page Setup" and "Fit One Page".  The panorama will be printed to a single long paper.  Alternatively you can upload the panorama for online printing.

Post

1) To publish the panorama to your website you need to scale down the master panorama.  Close the project by File | "Close Project".  Load "pano_skyscraper_v.tif" to PanoStitcher.  Click on main menu View | "Zoom..." | "Select image size".  Change Height from 949 to 500 to reduce the panorama to exactly the right size for this web page you are reading. Right-click in the panorama window to pop-up the panorama floating menu.  Select "Save at screen resolution" to save the reduced panorama as seen on the screen (at right is the resultant image).  

Fig. 7  Panorama that is precisely sized for web publishing.