2. Motion blur
• What is motion blur?
– Rapidly moving objects appear to be blurred in
direction of motion
• What causes motion blur?
– In real cameras, film is exposed to moving scene
while shutter is open
• Why do motion blur?
– Adds realism, cinematic look to games
– 24fps with motion blur can look better than 60fps
without
10. Algorithm
● 1. Render scene to texture
- At current time
● 2. Calculate velocity at each pixel
- Another Buffer
- Calculate current position – previous po
sition
● 3. Render motion blurred scene
17. What are the fault?
● Without knowledge of object edges
● Velocity outside silhouette of object is zer
o(= no blur)
● Solution : Geometry distortion
20. Matthias Wloka's trick
● stretch object geometry between previous
and current position
● Compare normal direction with motion ve
ctor using dot product
● If normal is pointing in direction of motio
n, transform vertex by current transform,
else transform it by the previous transfor
m
● Not perfect, but it works
26. Well... Not Perfect
● Not information to avoid occlusion artifact
s
● Number of samples needed depends on a
mount of motion
- 8 samples is good, 16 is better
- Ironically, more samples will reduce fra
me rate, and therefore increase motion m
agnitude
31. Skinning limitation in DX9
● 256 vertex shader constant registers limit
● Our characters have an average of 54 Mat
rix per drawcall
● For motion blur we need previous frame b
one(Matrix)s transformations
● If Bone == Quaternion & Tlanslation then
must be Uniform Transform
● Or decrease bone count
32. So....?
● In RS3 for Now
● Using Pixel Motion Blur = Only Object’s Tr
ansform
● Animation’s Proceed = Using Accumulatio
n Buffer
● Any suggestion?
33. Reference
● Stupid OpenGL ShaderTricks -Simon Green
● Pixmotor:A Pixel Motion Integrator - Ivan Neulander
● Interactive Real-Time Motion Blur - Matthias M. Wloka & Robert C.
Zeleznik
● Motion Blur Using Geometry and Shading Distortion - Natalya Tata
rchuk, Chris Brennan, John Isidoro
● Pixel Motion Blur - Direct X SDK
● Motion Blur as a Post-Processing Effect - GPU Gems 3
● CrysisNext Gen Effects -TiagoSousa
● Hardware Accelerated Motion Blur Generation -Clement Shimizu, A
mitShesh, BaoquanChen
● Motionblur - Myia
● http://incrysis.com/forums/
● Capcom presentation on Lost Planet