Jump to content

motion blur with velocity pass


rhlkvr15
 Share

Recommended Posts

good evening forum.....

i am rendering an architectural walkthrough and need to add some motion blur to the video.....i tried with VRay Physical Camera but it makes the rendering very slow....does anyone here know how to make motion blur in post production in AE using any pass while rendering......i searched the web for tutorials but didn't got any......please share the link if anybody got the tutorial......

 

Thank you.....

Happy Weekend......

Link to comment
Share on other sites

+1 to what john said. The velocity pass is like any other additional render element (alpha, depth, etc) that provides you with more flexibility in your compositing environment. RSMB can do a motion blur calculation without a velocity pass (it calculates changes in pixels from one frame to the next, or you can provide your velocity pass for a more accurate calculation.

Link to comment
Share on other sites

  • 8 months later...

Hello, I didnt want to start a new topic. Im using rsmb but I have inaccurate motion blur in my video. Maybe im exporting the pass wrong from elements. My main question is: At vray pass, should i change the number in "max velocity" and make it the larger value? Cause i left it at 1.0 though i have way larger values in all my animation. I can assume that this is it and i wanna make it clear before i re render. Thanx

 

ps. Also the shutter speed in my camera, has anything to do with the Velocity pass? In general i control the motion blur from there when i bake it from camera, but i have no clue if shutter speed affects the pass also.

Edited by thanulee
Link to comment
Share on other sites

My understanding is that the number should represent the maximum distance in pixels that any object will travel onscreen from one frame to another. So if you leave it at 1 then I assume there is practically no value being rendered in the pass. Is your whole velocity pass grey?

If you are using a VRay Cam then the shutter speed will obviously affect the exposure if you have 'exposure' checked. Shutter speed will affect your rendered motion blur, but I assume you are not rendering MB or you wouldn't need the velocity vector pass.

I think it will affect your velocity pass if you have MB enabled in Vray cam.

A typical workflow would have MB unchecked, so the shutter speed would not affect the velocity pass.

Edited by Tommy L
Link to comment
Share on other sites

oh, yeah, I was thinking about it the other way around. If you leave it at 1 then the velocity will be at 100% for any object that moves one pixel. Figure out the farthest something travels onscreen for one frame, use that as your '100%' MB. If your number is too BIG then everything will be grey.

And no, you dont need 32bit. I think RSMB in AE crunches stuff down to 8bit for computation anyway, but I may be wrong there. At 8bit you'll still have 256 degrees of MB which is plenty.

Link to comment
Share on other sites

Well, things are like u said. I have one more question though. Should i use the maximum value I see in my scene or maybe something less? My image sequence with the maximum value had very few blur and mostly in the parts that was going very very fast. thanx again

Link to comment
Share on other sites

  • 2 weeks later...

Anyone plz? In the max value field, if i enter tha maximum value i actually have on my scene, then the pass is almost grey. Thus in post i get very subtle to no blur at all. What is the actual number i must enter in max value? Maybe max value represents the shutterspeed? I can enter a random small value and teat, but that is not the case. I need to be know what im doing! Thanx

Link to comment
Share on other sites

According to this tutorial the number you enter is not random

http://www.timsportfolio.co.uk/tutorials/velocity-pass-3ds-max/

Everything works as described there, but my maximum value is just not corresponding as should. Its very very subtle though i have a bug that moves its wings like every 2 frames.. The pass doesnt seem to separate the very fast with the almost still items. So if map is wrong, in post cant do shit... It blurs everything if i add too much mb... So anyone knows what max value represents? Thanx

Link to comment
Share on other sites

I didnt say its random, I said its not based on physical values. Its computed in 'screen space', rather like a post effect, or thats my understanding of it. If you have an object you want to blur in isolation then you could render that object seperately. Just geometry, you wont nee lights etc so it will render in 2secs a frame and you can use the blur map in post.

Link to comment
Share on other sites

Thats what i ve been doing but its kinda stupid and its not 2 secs per frame when u got a full HD project :) Plus its a heavy post process which doesnt quite rendeds in AE that fast in my 6 core computer... Well, i guess i keep experimenting till my deadline drops :D thanx mate

Link to comment
Share on other sites

Thats what i ve been doing but its kinda stupid and its not 2 secs per frame when u got a full HD project :) Plus its a heavy post process which doesnt quite rendeds in AE that fast in my 6 core computer... Well, i guess i keep experimenting till my deadline drops :D thanx mate

 

turn off lights, GI, materials and reflections globally in the Vray panel and it will be 2 seconds a frame.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...