This example uses three layers of star field images to wallpaper the background of three containers.
Here are the images reduced in size to 100x100 pixels.
By creating the images with large areas of transparency, you achieve the effect of permitting the viewer to
see down through all the layers and visually ascertain a single image from all the layers. Then when
the effect of applying different rates of acceleration to each layer is applied the affect on the viewer is
one of depth. I've seen the effects combined with very cool masking techniques
(Hyper Lander is one such project
that involved such techniques to achieve an earth quake effect throughout the boards of the game.)
Because the images are transparent
1. Browser Caching
Developers tend to turn off their browser caching... this condition can result in pounding the server for graphics each time modifications to an image object (yes backgrounds too) are made... ie every 50 milliseconds another GET for "graph1.gif" shows up in the access log on the server. Check for this before you burn up your bandwidth or upset your sys admins! Suggestions for resolutions to this problem are welcome (please don't suggest pre-caching unless you can demonstrate that your method actually works with browser caching turned off)