Stitching Digital Panoramas

I. General Instructions

1. Develop your photographs (assuming you shot with an analog camera) and scan them. Scanners are available on all machines in the Graphics Lab. 72 dpi resolution will probably be adequate, especially if your camera is not of the highest quality. Do not exceed 144 dpi resolution. Save the scans in JPEG format with file extension .jpg. It is not necessary to add compression at this stage. If the total bit size of your images exceeds 15 MB, you should reduce scanner resolution or image dimensions, or use Photoshop to re-size your images.
   
   
2. Save your JPEG files to a Zip disk. Give the files names that include a numbered sequence, e.g.: Image01, Image02, Image03... Be careful not to name any images out of order.
   
   
3. Go to the Hypermedia Room on the fourth floor of Charles Royal. This is the smaller location with ten machines: seven PCs and two Macintoshes. Decide whether you wish to work in QuickTimeVR Authoring Studio, which is only available on the Macs, or in Spin Panorama, which is on both Macs and PCs. Spin Panorama seems to do a better job of stitching, though unfortunately it does not allow hot spots (next week's topic), so everyone will have to use QTVRAS eventually. If you'd rather work at home, you can buy Spin Panorama from PictureWorks (www.pictureworks.com) for $49.95.

Instructions for QuickTimeVR Authoring Studio (Mac only)

1. From the File menu in the Authoring Studio, select New and on the submenu select Panorama Stitcher. Save your Stitcher file to some appropriate directory, such as a new folder on the Desktop. Remember the location of this directory. All component files will end up there. Give either your directory or your file names some unique feature by which they can be recognized, such as your last name.
   
   
2. Open the directory or disk that contains your source images. Select the images, either one by one or all at once, drag them over the QTVR Authoring Studio window, and release the mouse button. In a few seconds you will see representations of all your source images. If these images are not rightside-up, use the Rotate arrow tools (left side of screen) to correct them.
   
   
3. Click on the Image Alignment button and fill in the number of degrees between each shot in your sequence (e.g., 36 degrees for a sequence of 10 images).
   
   
4. Click on the triangular icon between the first and second images in your sequence. This will open the Pair Alignment window. In that window find the size reading, which in most cases will say 100%. To the left of this indicator are two icons showing stylized mountain ranges. They control display scale. The icon furthest to the left reduces scale. Click this icon until your scale is set to 75%, 50%, or some other setting that lets you see the edges of the images.
   
   
5. You should see two translucent, overlapping images. You can drag either image to reposition it. Drag the image on the right down and to the right until you can separate it clearly from the image on the left. Find some feature in the righthand image that also appears in the lefthand image. Reposition the righthand image so the two versions of this feature overlap as closely as possible. You may not be able to achieve a perfect match; try to average out the discrepancies. A certain amount of blurring is unavoidable, but some if not all of it will be removed by the software. When you are ready for fine adjustments, use the arrow keys on your keyboard to nudge the righthand image one pixel at a time.
   
   
6. Once the two images are properly positioned, click the button labeled Zero immediately above the image window. This tells QTVRAS to accept the current pair alignment. If you don't do this, the program will try to align your images based on its own readings. You won't like the results.
   
   
7. Click the Next button in the lower lefthand portion of the window to proceed to the next image pair. Repeat the alignment step for all pairs (i.e., stop when you come back to Image01/Image02 again).
   
   
8. When you have completed your last pair, click the OK button in the lower righthand corner of the Pair Alignment window. Now click the Stitch Pano button at the upper right of the main QTVR Authoring Studio window. The rest of the process is automatic, though it involves several steps and may take a while, depending on the number of images in your panorama, their size and resolution, and the speed of your machine. On a 200 MHz PowerMac, a 20-shot panorama using 640x480 images at 72 dpi takes between 5 and 10 minutes to stitch. The three Macs in the Hypermedia Room rank as fast (iGor the iMac), moderate (Olive Oyl the 8600), and pokey (Jughead the 7500); but even on the slow machine you should be done in under an hour.
   
   
9. If you encounter an error saying that your images add up to more than 360 degrees, find the checkbox that says "Wrap Images," de-select this option, and click Stitch Pano again -- OR switch to Spin Panorama (below), which seems to do a better job of counting degrees.
   
   
10. Once stitching is complete, your panorama will open in a QuickTime window. Fly around to check it out. Zoom out for the most complete view.
    
    
11. Save all your files to your Zip disk. Note that QTVR creates several intermediate files -- a PICT file and a tile movie as well as a panorama. Only the third of these (the .pano file) is required to play back your panorama, but you will need the PICT file if you want to edit it. Save everything.

Instructions for Spin Panorama (Windows and Mac)

1. Find the Spin Panorama application and launch it. On Windows machines it will be on the Start Menu under PictureWorks.
   
   
2. Copy your images from your Zip disk to some appropriate directory on the lab machine, such as a folder with your last name on the Desktop or the D-Drive.
   
   
3. In Spin Panorama, click on the Get Photos tab and then click the Browse button. Navigate to the location of your source images. When you are looking into the directory that contains all the images, Select Open. Spin Panorama will index all your images automatically. Don't worry if it includes some you don't want. The indexed images will appear as thumbnails in a scrollable window on the righthand side of the Get Photos tab.
   
   
4. Drag the images you wish to include one at a time into the working area of the Spin Panorama window (it has a pale parchment color). If you drag in an incorrect image, click on it in the working area and press the Delete key (NOT the Backspace key!) and it will vanish. Images come in on the right by default. You should be able to check image order visually as you go.
   
   
5. Once you've loaded all images into the working area, click the Stitch tab. You'll see stitching guides superimposed on each pair of images. These look like stylized barbells. You want to connect the circular part of each icon to features in the two images that coincide. Choose features that are recognizable by color and/or shape in both images A detailed or magnified view of the area under the circular parts of the stitching guide appears in the windows on the Stitch tab. The object of the game is to position the ends of the stitching guide so that the two detail views are visually identical, or as near as you can make them.
   
   
6. When you have the upper icon positioned properly, start on the lower one. Set the two stitching guides (the barbells, that is) as far apart vertically as you can manage.
   
   
7. When both stitching guides are in good places, notice the red arrow icons above the Spin Panorama working area. Click on them and they will turn into blue arrows pointing outward. Your image pair will also be stitched. If you don't like the results, click the arrow icons back into their red (unstitched state) and reposition the stitching guides.
   
   
8. When all your images are stitched, click on the Crop tab. Use the horizontal lines at top and bottom of your stitched image to elminate any weird spots or artifacts.
   
   
9. Proceed to the Create tab. Select Save as Image File. This will output your stitched, panoramic image as one very wide JPEG. Give it some recognizable name (perhaps using the word "stitch") and save it to an appropriate directory.
   
   
10. Select Save as VR Movie and click the button labeled Open panorama after saving. This will output your stitched image as a QuickTimeVR panorama. Save this movie file (which will have the extension .mov) and the JPEG file to your Zip disk.