Tutorial 4: Beach Mirrors

Note:  This is a challenging advanced  project, which will give you experience in overlaying image pairs with very vague common features.

Objectives 

1) use the Overlay method to stitch a partial panorama from photos with few distinctive shared features,

2) transform the panorama using the Unbend panorama / Rotate panorama features to straighten and make the ocean horizon horizontal,

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

4) 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 exposure to Auto mode. 

2) Tilt the camera to position the horizon roughly in the middle of the frame.  Take overlapping photos handheld while turning around. Try to stay on one spot as you turn. The overlap is about 25%.

Transfer photos from camera to computer

Load the photos from the camera's memory to the computer in the directory named "sunset".

Open PanoStitcher

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

Load

1) Click on the Stitch Toolbar Load button.  The Image Browser window pops up. 

2) Go through the folder hierarchy in the left pane to open the folder "mirrors".  The middle pane shows all the .JPG files in "mirrors".

3) While pressing [Shift] key, click on mirrors001.JPG and then on mirrors003.JPG.  All files between the two are selected.  Click "Load Selections" to load the three selected images to PhotoBench. 

Fig 1. PhotoBench containing the sorted photo thumbnails

Settings...

1) Click on the Stitch Toolbar "Settings..." button to bring up the "Stitch settings" dialog box.

2) Set Focal length to "Known" and set the value to 28mm (the focal length used for taking this photo set).. 

3) Select Stitching Mode to "Manual".  Auto mode would have difficulties because the photos are dominated by the moving ocean waves while the static areas (cloud and dark coastline) have few distinctive features.

4) Make sure "Auto-balance intensity" is checked (the photos have different brightness since the camera auto exposure was used).

5) Click OK.

Stitch

1) Click Stitch.  The window "Adjust Image Pair Overlap" containing the first two images appears.

2) Put the cursor somewhere around the anchor. Drag to shift the foreground image around such that the clouds and the horizon line register.  Then use arrow keys on the keyboard to fine-tune the shift.

3) Click and drag the anchor to the middle of the overlap area on the horizon line.

4) Put the cursor far away from the anchor but still inside the foreground image.  Click and drag to rotate the foreground image around such that the horizon line from the two images is straight.  Then use [Ctrl] + arrow keys on the keyboard to fine-tune the rotation.

5) Click Stitch. Or, right-click  in the "Adjust Image Pair Overlap" window to pop-up its floating menu and choose "Stitch this pair".  The Panorama Preview window opens displaying the stitched images.  Click Stitch again to show the window "Adjust Image Pair Overlap" containing the next pair of  images.  Repeat the process until all image pairs are stitched.

Fig 2a. Image pair 1 & 2

Fig 2b. Image pair 2 & 3

Fig. 3a  Raw panorama preview

Fig. 3b  Panorama preview with ocean horizon straightened and leveled.

4) PanoStitcher already automatically adjusted the photos in the panorama.  However, you might want the ocean horizon to be perfectly straight and level.  Right-click in the panorama preview window to pop-up the floating menu.  Choose "Rotate panorama".  Click and drag vertically on the panorama until the horizon is level (though still bent).  Then pop-up the floating menu again to choose "Unbend panorama".  Click and drag vertically on the panorama to straighten the horizon. 

Blend

1) Choose Resolution Ratio 75% which corresponds to a panorama size of 694 x 335 pixels. 

2) Click Blend to make the panorama (automatically cropped).

Now the panorama is made!

Edit

1) No action needed.

Save

1) Click on File | Save Project to save the stitching project to the project file mirrors.psp in the "mirrors" folder. Later you can continue working by loading this .psp file to PanoStitcher and clicking Stitch.

2) Click on the Main Toolbar "Save image" icon to pop-up the "Save Panorama Image" window.  Save the panorama to the name "pano_mirrors.tif" which is uncompressed.  This is the master panorama for future use.
3) Click on the Main Toolbar Print icon to bring up the visual printing utility.  Set page Orientation to "Landscape" in the Setup | Page Setup dialog box. Right click in the panorama window to pop-up the print floating menu and choose "Fit 1x2 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 three 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.

Post

Click on the Post page tab to show the Post menu.
1) Right-click on the panorama and select "Set as Screen Saver" to pop-up "Display Properties".  Select the Screen Saver tab.  If Pixtra PanoScreen is the current screen saver, the "pano_sunset.tif" thumbnail preview should already be spinning.  Otherwise you need to select PanoScreen from the screen saver drop-down list. Click "Settings..." to pop-up the Pixtra PanoScreen Configuration window.  Change the spin-speed or add the panorama to a PanoAlbum.  Click OK to finish. In the Screen Saver menu click OK to set "pano_mirrors.tif" as the screen saver of choice.
2) To publish the panorama to your website you need to scale down the master panorama.  Load "pano_mirrors.tif" to PanoStitcher. Click on main menu View | Zoom... | Select image size.  Change Width from 2678 to 570 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 (below is the resultant image).  You can also click on [Web] to automatically generate a dynamic web page using the Applet or the ActiveX plug-in. 

Fig. 4  Panorama that is precisely sized for web publishing.

Fig. 5  The master panorama (from resolution Ratio=75%).