VR Toolbox

Before a panoramic image can be compressed, it is divided up into tiles, each tile representing a small area of the panoramic image. To determine the size of each tile and the number of tiles the panoramic image will be divided into, the dimensions of the tile array must be specified. The tile array is expressed in terms of rows-by column. The size of the tile and the dimensions of the tiling array can have a great effect on the performance of the QuickTime VR panorama, as the viewer is interacting with it. It can also have a significant impact on the RAM requirements of the panorama. For example, a case where a 2400 x 800 pixel panorama is divided into a 1 x 24 tile array. The width and height of each tile is 100 x 800, respectively. If the playback window is 320 x 240 pixels and the viewer is zoomed out as much as possible, four tiles representing 16.6% of the image data will have to be loaded into memory and decompressed to display the panorama.

The drawback to having more tiles is that a greater emphasis is placed on disk input and output, since more tiles will have to be retrieved and displayed while interacting with the viewer. It also results in less efficient compression ratios and hence a slightly larger file size.

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