Methods for Shooting QTVR

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Contents
Equipment
Shooting
Building QTVR panoramas from your pictures

This page describes an effective, standardized system for shooting QuickTime VR panoramas, with some helpful tips. Full documentation of QTVR software and hardware is available on Apple's QTVR web site.

Good QTVR starts with the best possible pictures. For more information on image standards, digital file sizes, compression, etc., see the Stoa's photography standards page.

Tour ancient sites!

Bruce Hartzler's QTVR panoramas of Greek sites are available on-line in his Metis project.

Equipment

Most people will choose to use digital cameras to shoot QTVR. While this document is written to describe digital shooting, most of what is included here also applies to shooting QTVR with a film camera. Bruce Hartzler's QTVR was taken with a Kodak DC210 digital camera, a Bogen tripod with a ball head, and a Kaidan Kiwi Plus QTVR head. The camera lens was 28mm. The Kaidan head has changeable rings (detente disks) with preset stopping points marked around them, so it's easy to take evenly spaced pictures, 16 to 24 for a 360 degree panorama. Bruce used 4 20-mb cards to store the photographs, and downloaded them to his laptop computer as soon as he could after shooting. The cards could store about 30 frames per card at the camera's high resolution setting (about 1200 x 800 pixels). The average image size was about 200k, JPEG'd at a high quality setting.

Important digital camera features include long battery life, lots of space for image storage, a high maximum resolution, and exposure lock. The first three features will make it easier for you to spend more time shooting and to acquire the best pictures possible. Exposure lock allows you to set one exposure and use it for all pictures in the panorama, regardless of whether individual views are brighter or darker. Using exposure lock enables you to get a good average exposure for the entire 360 panorama, and will allow the final product to blend smoothly into a seamless whole.

To use exposure lock, take test shots or light readings at the node point, using the views with the deepest shadows and the brightest highlights, and find an average exposure setting in between the two extremes. Then lock the camera's exposure setting to that average. Practice trying to find the best average exposure; it's a skill that comes with time.

Shooting

1. Get a good overview of your site.
First, walk through the site, and decide where to place nodes where you will shoot panoramas. Prioritize essential and transitional nodes. Essential nodes are ones you definitely want to have as part of your tour, that feature significant buildings or parts of the site. Transitional ones are used to link between the essential nodes, to provide continuity to the walkthrough. Use a map and mark your node points on it, for future reference.


Tips on Choosing a good place to shoot a node

Make nodes evenly spaced as possible, so the transitions will not be too sudden and jerky. Keep in mind that your node should have some distance contrast: part of the node should show things that are close to you, while part of the panorama should show things that are far away. A node taken in the middle of a field is boring; stand close to one structure in order to fill the frame with it. The best nodes are ones where there are both near and far objects. Balance this with getting a completeness of view -- make sure the node includes one key building or structure framed in its entirety.


2. Take the pictures. If you use a ball head tripod, you will not have to adjust the height of your tripod legs in order to level the tripod. Try to put the camera about 5.5 feet up from the ground, to approximate an average person's height. Read Apple's documentation for setting up your camera so the film plane is directly over the axis of rotation.

To find an average exposure for your node, take a light reading or set your camera using the part of the panorama with the most average midtones. In order to get consistent exposure, use exposure lock, as described above in the equipment section. With this lock, you can take as few as 16 shots around for the panorama, using the preset stopping points on the Kaidan head's detente disks, or detente points on your own QTVR head. (If you do not have exposure control on your camera, plan on taking many more pictures in order to get a good exposure for each frame. Take 24 shots every 15 degrees without exposure control. Blending is easier if there are more pictures around: the more overlap, the better. Also, bracket the views with the darkest shadows and the brightest highlights. Bracketing is shooting multiple versions of a view, with slightly different exposure settings. For more information on bracketing, see the tips below, or the photography guidelines.)


Tips on picture-taking

Mornings and evenings are best for shooting, with better shadows and highlights, even though some pictures' highlights will be over-bright or shadows over-dark. Try to do the whole site on one particular day, so there is an evenness to the transition between nodes. Or attempt to shoot at the same time of day, if the site is large. Weather differences day-to-day will show up in the panoramas, otherwise.

You might have to move around the site and shoot nodes out of sequence, in order to minimize the presence of people in the pictures. People can be helpful, to provide scale, but it's hard to get them to stand still. If you include people, make sure they stand still, because if they move it will cause problems during the stitching.

Pictures of additional things on the site can be linked to your panoramas as 1-frame object movies. It's easiest to shoot these after you finish a node, looking around you to see other possible views you might want to link up.

Use bracketing to ensure you get a good exposure for each view. Bracketing is when you take additional pictures of the view with the aperture slightly more open or closed than is indicated by your light meter. You can do this with your camera by finding an average exposure for the panorama, locking it in, shooting the panorama, then going back to particularly bright or dark views and turning off the exposure lock, allowing the camera to automatically choose a better exposure for that particular view. Later, you can compare the two exposures of the same view and use the better one.

Once you are comfortable with the QTVR shooting process, you can try an advanced technique like changing the camera's axis of rotation so it is not level to the ground. The camera's rotation axis only has to be level to the plane underneath the camera, the plane of the QTVR head and the detente disk. Using this method, you can shoot a QTVR panorama that looks over the side of a structure, then back up to its top. See Bruce's QTVR movie of the Athenian acropolis, which includes a node looking over the edge, as an example, or go to the Apple documentation pages for more information.


Building QTVR panoramas from your pictures.

1. Store the pictures.

Back up your pictures as soon as possible after taking them. It would be horrible to do all the work then lose the pictures. Zip drives are not practical, because they are too small. Jaz drives or better. If you have access to a CD-ROM writer, a DAT drive, or extra hard disk space, that's best. Two copies of each picture should exist, preferably in different physical locations, to avoid losing any data.

If you shoot onto film, once the pictures are scanned, you should also keep two copies of the digital versions, to avoid having to rescan them in the future.

2. Stitch the pictures together.

Depending on the final use you have for the QTVR panoramas, you may want to use different settings in the stitching process. The following description includes all the methods and settings Bruce used to make his panoramas for web delivery in his Metis project.

It's easiest if you first organize the files on your computer. Bruce used Portfolio, an image organizing tool, to organize, rotate, and select the particular shots from the numerous bracketed shots. At this point, you can also edit the views you will use, adjusting levels, color, contrast, etc. Do not resize the pictures at this point; you should try to stitch with the highest quality images possible. Once you designate and clean up the particular 16-24 views you'll use to construct the node, and number them in order (a shareware tool called Drop-Rename is useful for renaming large quantities of files), you can copy them over to a folder on your hard drive named for the node.

Bruce used Apple's QTVR Authoring Studio 1.0 to stitch his panoramas. The software includes lens files you can use to select the particular lens and number of views you took in a single node. The stitching process is easily automated, and if you use a consistent method of shooting, you will be able to use the same stitcher settings for all of your nodes. Based on the size of the original JPEG files, Bruce produced a final panel that was approximately 620 x 3456. In order for your QTVR panorama to be compatible on Windows machines, the dimensions of the final panel are important. Make sure you check the QTVR manual or on-line documentation for important restrictions concerning the size of the images.

Back up the final stitched panels in the same way you backed up the original photographs, so you won't have to go through the whole process again.

3. Prepare multiple nodes in a scene for Web delivery.

Bruce resized the panels to 360 x 2016, a much more manageable size for the Web. Using Photoshop, he sharpened the panels, since resizing them causes them to lose their sharpness. Don't use the Sharpen or Sharpen More tools; rather, use the Unsharp Mask, a much more precise tool. Play with the settings in Unsharp Mask until you get a good result.

At this point, using the QTVR software, you can lay out your scene with Panorama Makers, putting in hotspots, URL links, links between the nodes, and so forth. See the QTVR documentation for more information. When he was ready to go ahead and make movies from the panels, Bruce set the software to create 1 horizontal tile and 4 vertical ones, compressed as high quality JPEGs. He used smaller numbers of tiles because JPEG does better on the compression when it has more information. Finally, he made the movie with a window of 372 x 164. With the 360 vertical pixels of the movie displayed in a 164 pixel high window, there is some play, and users can scroll up and down a bit in the scene. The biggest of Bruce's scenes contains about 70 nodes, and using the method described here, the total file size for the scene is under 12 mb.

More information on general technical aspects of QTVR is available on the Apple QTVR site.

Bruce Hartzler, University of Texas, Austin
as told to Maria Daniels
Perseus Project


 
 

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Please send your comments concerning The Stoa: A Consortium for Electronic Publication in the Humanities to Ross Scaife (scaife@stoa.org). This document was published on: 23 April 1999