Transcript Powerpoint source

Omnidirectional Rendering
Jiesang Song
Stephanie Weirich
Motivation
 Rendering is neat
– Many video games strive to immerse the
player in an imaginary world.
 Rendering is slow
– Complexity is based upon the number of
objects in the scene, as well as the
number of pixels in the output.
Quake screen shot
Riven screen shot
Inspiration
 Columbia
Omnicamera Teleconferencing
 Quicktime VR -
Panoramic Imaging
Methodology
 Render complex scenes ahead of time
in an “Intermediate Image”
 Compute several perspective views
from that one image
Methodology
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POV Source
Hemisperical view
Perspective view
Parabolic Mirror
Generalization
 Parabolic mirror defines a function
between the angle of elevation, , of
a ray and the radial distance, r, of its
location in the image.
1 sin 
r
cos 
Generalization
 We don’t need to follow physical laws
 We can use (almost) any function of  we
wish!
 Parabolic mirror model shows us how
Generalization (Cont)
Different functions allow us to adjust the
resolution of parts of the image
Fisheye lens - r is linear in 
Another function might allow us to have more
resolution near the horizon.
Parabolic Mirror
Fisheye lens
Implementation Overview
• Initialize windows application
• Initialize DirectDraw Surface in Video memory
• Read in .PPM files
• Run conversion algorithm
• Initialize Device Independent Bitmap (DIB)
• Stretch and copy Bitmap into DirectDraw Surface
• Enter message processing loop
Interface
 Move mouse to pan image
 Use left/right mouse buttons to
zoom in and out (limited depth)
Performance
 About 1 – 3 seconds to generate new
640*480 or 320 * 240 images on
Intel Pentium 200 MHz running
Win95
 About 5 – 9 seconds for 1024 * 768
images but takes longer to initialize
 Room for optimization