Motionblur3d

[user_deleted]

I've got a card spinning like a propellor in 3d and would like to motion blur it. I've been playing with the motionBlur3d node + the vectorBlur, but it only seems to blur based on camera movement, not object. How would you guys approach this?

[user_deleted]

yes, MotionBlur3D is only camera based.
Besides VectorBlur always blurs each Pixel into a straight line so it's not of much use for circular motion.
Brute force would be using the multi sample motion blur (setting the samples in your render node real high). This will take forever though and might not look very good anyway. The propeller motion blur thing has always been a tricky one to get to look right.
I'd recommend playing with a mix of a a texture mapped plane and multi sample motion blur. The texture should be an animation of something that kinda resembles the real blur effect so best to collect some reference, animate some spinning Beziers with soft edges or so to approximate the look in 2D, then map that onto a plane and pipe it through the render node with multi sample blur on top
.
It'll take a moment until you get a grip on the mix but that's how I used to do it. I believe there might be some tutorials out there on the web as this problem tends to come up again and again.

cheers,
frank

[goee]

A simplier approach would be to deal with it before you enter the 3D "module". Animate them spinning and then add a TimeBlur, TimeEcho and FrameBlend. They three combined with the correct settings can give a base look of what the motion blur of a propeller looks like.

Here is a very basic setup:

set cut_paste_input [stack 0]
version 4.5027
Constant {
inputs 0
channels rgb
format {"512 512 0 0 512 512 1 square_512" 0}
name Constant1
selected true
xpos -256
ypos -192
}
Bezier {
points {{
{18 256 59.4 1.54 59.4}
{256 262 59.2 0 59.2}
{492 257 59.2 -1.6 59.2}
{255 253 59.4 -3.14 59.4}
}}
shape {{curve L x1 0}}
center {256 256}
p1 {100 400}
p0 {100 100}
name Bezier1
selected true
xpos -256
ypos -123
}
Radial {
area {231 229 282 282}
softness 0
p1 {100 400}
p0 {100 100}
name Radial1
selected true
xpos -256
ypos -97
}
Crop {
box {0 0 512 512}
reformat true
name Crop1
selected true
xpos -256
ypos -71
}
Transform {
rotate {{curve x1 0 x100 1000}}
center {256 256}
name Transform1
selected true
xpos -256
ypos -45
}
TimeBlur {
offset 0
name TimeBlur1
selected true
xpos -256
ypos -19
}
TimeEcho {
framesbehind 3
frmaesfade 3
name TimeEcho1
selected true
xpos -256
ypos 7
}
FrameBlend {
name FrameBlend2
selected true
xpos -256
ypos 33
}
Retime {
input.first 10
input.first_lock true
input.last_lock true
output.first 0
output.first_lock true
output.last 90
output.last_lock true
warp {warp {curve C 0 1}}
name Retime1
selected true
xpos -256
ypos 73
}
Retime {
input.first 0
input.last 90
output.first 0
output.last 25
speed 3.6
warp {warp {curve C 0 1}}
name Retime2
selected true
xpos -256
ypos 99
}

I hope it helps.

Cheers,
diogo

[user_deleted]

hey excellent tip! I was settling for adding a dirBlur with radial type right after the read node. It is a bit smooth and it is dreadfully slow. I'll try your suggestion!