QTVR Project

Here's a project for making a Quick Time Virtual Reality (QTVR) stage for creating objects or movies using Apple's QTVR software.

The software allows two kinds of products to be made. The first, the panorama, is where an external scene is examined in 360˚ by clicking in the scene and moving the mouse left or right, up or down. The subject moves in response to the mouse. To build the panorama a series of images are made by rotating the camera 360˚ and making photographs throughout the rotation. The software then seams the images together and joins the ends.


The second approach is to photograph an object that is rotated in front of a motionless camera. This was my objective. The result is an object that allows the mouse action to rotate the subject by clicking and moving left or right, as if turning the object in your hands.
I first built a table to hold a lazy susan platform; a disk arbitrarily 24" in diameter. The spinning apparatus was only $7 at a local hardware store. Medium Density Fiberboard ws the matrial for the tabletop and lazy susan. The first challenge was to inscribe a circle, which is hard than it seems. I used a string with a pencil tied 12" away and pivoted around a nail in the center. But it's too hard to hold the pencil vertical. I then tried a small board with a hole for the nail and a hole for the pencil. This worked better, but was not completely accurate after all.


The QTVR software recommends 36 images. The next challenge was to divide the circle into 36 10˚ segments. Geometry was not my strong suit in high school, and I soon gave up on trying to devise a Pythagorean method for accurately determining the segments and turned to Photoshop instead.*


Once the template was drawn, I added a 1" grid and printed it on 24" wide paper. I marked the positions along the circumference and then drilled a vertical hole before then cutting out the circle with a saber saw. The saw cut bisected each drilled hole leaving an indent every 10˚ on the circle. This would allow each reference point to be located as the turntable was rotated.


The purpose of the grid was to be able to photograph from overhead to provide an approximation of the size of the object by measuring against the 1" grid. The only problem with this solution, however, was how to get the camera in position from above. My solution was to incorporate a mirror at 45˚ located above the turntable. As you can see from the profile, I built a gallows affair that also holds the background paper.



For the trial I used an ancient Graphlex camera. The lighting is pretty simple and documentary: two sources equidistant from the camera position. The camera had to be adjusted for the overhead view, but no ladders were necessary. The mirror is pretty clear; it came from a copy machine that was cannabalized for parts.



This movie is not interactive, but can represent the effect.

*Here's the technique for creating 36 equal segments of a circle. I created a Grayscale file 24" square @ 120 ppi. I added a layer and used the line tool to draw a horizontal line from edge to edge, halfway down from the top of the image. (Command R turns on the Rulers.) Command J copies the line layer, Command T invokes the Free Transform dialogue and 10˚ can be input in the rotation box in the options bar. Click Enter to accept. Copy the layer and repeat 18 times until all the segments are drawn. Or you can make 3 lines, merge them, copy and rotate the copy 30˚ to quickly get to six. Merge down again, copy and rotate 60˚ to get twelve. Merge down, copy and rotate 60˚ again to get twenty-four. Don't merge, but copy and rotate 60˚ to get to the final thirty-six.