motion blur in Render Man

[web_sdas]

請問有無人知道renderman的motion blur的原理
因為他同maya的似乎很不一樣
使我在render上出現一樣問題呢
先唔該各位

[h2o]

基本上 rman 既 motion blur 系 linear blur, 即系同 maya 2d motion blur 差不多. 當然咁樣系有問題, 不過都有方法解決既......

你可以講講你既問題, 一齊研究下都好

[web_sdas]

問題一:
當render有關realflow和realweave的objects和particles時會render不到motion blur.

問題二:
當render是包括一些character和realflow的particles, 在motion blur 是click 著了的時侯, render出來的圖會無了character只得particles.(當然亦有以上的問題,motion blur是唔work的)

請問用render man同realflow一起用時, 會有以上的問題是正常的嗎?
忘了說清楚一點, 我是把realflow的particle import入maya後再用render man 做render的.

[Joker]

除非你要 3D motion blur
否則還是建議 motion Blur 在後期中才做
這樣比較有彈性及節省時間同精力
也能夠避開兼容性的問題

[tdk]

基本上 rman 既 motion blur 系 linear blur, 即系同 maya 2d motion blur 差不多. 當然咁樣系有問題, 不過都有方法解決既......

你可以講講你既問題, 一齊研究下都好

as I know, the renderman motion blur is true 3d motion blur, it just the default value is only 2 samples which result a 2d linear looking motion blur, by attaching a motion sample attribute to objects, one can increase the sample up to 6 when needed (like propeller).

correct me if I'm wrong

[h2o]

as I know, the renderman motion blur is true 3d motion blur, it just the default value is only 2 samples which result a 2d linear looking motion blur, by attaching a motion sample attribute to objects, one can increase the sample up to 6 when needed (like propeller).

correct me if I'm wrong

冇錯, rman 既 multi-segment motion blur 最多有 6 個 steps, 不過 rman 基本應該都系 linear motion blur, 只不過喺 frame 與 frame 之間嘅 transform 再加多 6 個 samples, 所以出黎嘅效果好似 3d motion blur. 但系 multi-segment motion blur 系唔 support deformation, 所以我先認為 rman 嘅 motion blur 都系 cheat 架姐.

另外rman 既 motion blur 可以 render 得咁快, 我相信原因都應該系咁

p.s. 如果有錯, 請指正, 謝謝!


另外 web_sdas 嘅問題, 我都唔識添 , 因為我都未試過用 realflow. 不過我想知你個 mtorParticleBlurStyle set 左做咩? 有4種可以柬 globals/openOnFrame/centerOnrame/closeOnFrame, 唔知有冇關系... ...

至於問題二, character 同 realfow particles 分開 ren 得唔得?

[HammerChugoh]

M.....a linear motion blur doesn't necessary to be 2D....as long as you sample the motion step of the object in visual space in 3D cordinate, it's 3D motion blur.


quota from <https://renderman.pixar.com/products/tools/renderman.html>

"Render the highest quality images with features like advanced filtering and true 3D motion blur "

[web_sdas]

在此多謝各位的回答

h2o : "globals/openOnFrame/centerOnFrame/closeOnFrame, 唔知有冇關系... ... ", 這三個setting都有試過, 但我相信應該不關這個setting的問題, 因為這個只是用於決定出current frame, center of current and next frames, next frame的問題. 而我第二個問題的意思是說, click 著了motion blur之後, render了的圖, 當中的character會render不到出來(當然這個問題是指有realflow的particles包含當中的時候啦, 奇怪在character render 不到, particles 郤render到)

不過, 經過我的研究在render man 裡, 要render realflow 的 particles是有一些問題存在的, 其中之一是用不到motion blur. 若有新發現, 大家不況再研究研究啦.
在此學了不少有關motion blur的知識(因為本人不是太識motion blur的concepts)

所以在此再多謝各位的幫忙!!thx

[vectoreffect]

RenderMan is using velocity to calculate particle motion blur. When Maya import Realflow particle, the particle only has rfVelocity and the particle.velocity is empty. Therefore, you can't render motion blur.

You need to create a new Maya's particle has the same number as the Realflow particle. Then add this expression in the new particle:
particleshape1.position = realflow_particle.position;
particleshape1.velocity = realflow_particle.rfvelocity*5;

Remark: this expression should past on creation and runtime.

[vectoreffect]

One more thing, before you create a new Maya particle. You need to create a particle cache of the Realflow particle.

[web_sdas]

It is really work!!thx a lot!!