Car Dust

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Old 10 October 2010   #1
Car Dust

any general guidelines on how to obtain that dust effect with fluids?
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Old 10 October 2010   #2
emit particles that inherit the cars motion and then emit fluids out of particles.
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Old 10 October 2010   #3
I wouldnt even use particles, just lots of carefully placed volume axis fields and turn the car into a velocity emitter.
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Old 10 October 2010   #4
Originally Posted by stooch: emit particles that inherit the cars motion

-does this differ from just attaching a fluid emitter to the car?

-this is what i have so far: movie (right click save as). Any guidelines on how to make it more convincing?

-the fluid is not being motion blurred even with high values and when the simulation is cashed, any ideas?
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Old 10 October 2010   #5
...

1. differences have:
if you simply connect the emitter to the object, then the particles will be born and remain in place, if you include "inherit", then the particle will be some time follow the emitter.

p.s.: for fluids "inherit" use "motion field"

2. you have a buoyancy, but no directional movement, i.e. the fluids simply rise up and that's all, it's wrong. use the "fields" to give realistic simulations, and make fewer buoyancy.

p.s.: the best way is use density and temperature emission. temperature buoyancy - positive. density buoyancy - negative. because the dust is still heavier than air. (IMHO)

3. motion blur can be applied in post processing

good luck.
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Last edited by ZeitG : 10 October 2010 at 07:38 PM.
 
Old 10 October 2010   #6
Originally Posted by ZeitG: 1. differences have:
if you simply connect the emitter to the object, then the particles will be born and remain in place, if you include "inherit", then the particle will be some time follow the emitter.

p.s.: for fluids "inherit" use "motion field"

2. you have a buoyancy, but no directional movement, i.e. the fluids simply rise up and that's all, it's wrong. use the "fields" to give realistic simulations, and make fewer buoyancy.

p.s.: the best way is use density and temperature emission. temperature buoyancy - positive. density buoyancy - negative. because the dust is still heavier than air. (IMHO)

3. motion blur can be applied in post processing

good luck.


Mik , impressive work, i am trying to apply your tips.
meanwhile i am trying to have a look similar to your TrailV2, do you mind sharing your method?
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Old 10 October 2010   #7
...

why not...

p.s.: nothing fancy
Attached Files
File Type: zip dust_ground_trail_long.zip (14.6 KB, 191 views)
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Old 10 October 2010   #8
Just had a play..

http://www.jeremyraven.co.nz/images/carDust.mp4
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Old 10 October 2010   #9
Originally Posted by royterr: -does this differ from just attaching a fluid emitter to the car?

-this is what i have so far: movie (right click save as). Any guidelines on how to make it more convincing?

-the fluid is not being motion blurred even with high values and when the simulation is cashed, any ideas?

yes. the fluid solver is too buoyant. if you inherit velocity from particles you will get a more realistic result. otherwise it will just billow in a vertical fashion. i guess you could use it but to me it wouldnt look realistic. if you look at a rally car as it spits out dust, you will see that there is a highly directional aspect to it.
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Last edited by stooch : 10 October 2010 at 12:16 AM.
 
Old 10 October 2010   #10
Originally Posted by ZeitG: why not...

p.s.: nothing fancy

thanks alot man, you have been a great help.

here's where i got so far: movie
half poly cylinder = emitter = motion field = parent of a volume axis field.

Originally Posted by stooch: yes. the fluid solver is too buoyant. if you inherit velocity from particles you will get a more realistic result. otherwise it will just billow in a vertical fashion. i guess you could use it but to me it wouldnt look realistic. if you look at a rally car as it spits out dust, you will see that there is a highly directional aspect to it.

Dimitri does your particle method give better results then my last movie?
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Last edited by royter : 10 October 2010 at 09:21 AM.
 
Old 10 October 2010   #11
I think you need a stronger volume axis field.
You need to think about where the forces are coming from in real life. Most of the dust is being pushed by the car tyres as it grips the road around the bend, based on your photo resource. So your axis field ought to be driven from this point. Also the motion of the car will create a vacuum behind it sucking the dust in towards it hence the reason for the motion field parented to the vehicle. A combination of these fields working together with the correct magnitude and bouyency of the fluid should get some decent results.
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Old 10 October 2010   #12
Originally Posted by Aikiman: I think you need a stronger volume axis field.
You need to think about where the forces are coming from in real life. Most of the dust is being pushed by the car tyres as it grips the road around the bend, based on your photo resource. So your axis field ought to be driven from this point. Also the motion of the car will create a vacuum behind it sucking the dust in towards it hence the reason for the motion field parented to the vehicle. A combination of these fields working together with the correct magnitude and bouyency of the fluid should get some decent results.


ok, here is the scene.
could you illustrate your method?
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Old 10 October 2010   #13
Im using 2008, scene doesnt appear to have loaded properly. Have a look at the movie I uploaded, I just tweaked it a little and uploaded a newer version a couple of posts back.

The volume axis field has an 'around axis' attribute also that can twist your fluid vectors creating more interesting patterns, its just a matter of getting the magnitude right and timing.
I cant really see any use for particles it would just make th effect more complicated than it needs to be unless you want to add flying debris.
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Old 10 October 2010   #14
Originally Posted by royterr:
Dimitri does your particle method give better results then my last movie?


yep. you can clearly see the lack of directionality, and how the smoke just kind of does its thing instead of inheriting the velocity of the emitter.

Also you want to simulate jets of dust shooting from under the wheels, and those have their own directional vectors, things taht you can previs with particles (which are much easier to manage and control than fluids).
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Old 10 October 2010   #15
...

the trick is that you should be about 6 fluid emitters and 5 fields.
on the emitter on each wheel, one on the bottom of the car and one behind some sort of common cars. as well as in life.
the main thing here is not to overdo it with the total density of fluids.

Fields should be at each wheel, and again the total light field behind the car. motion field should be across the body, even a little longer.

important point is the vehicle animation itself (its movement and rotation) and, accordingly, the direction of the fields for the emission of dust.

This effect is quite complicated and one should not think that it is possible to realize handsomely for one or 2 days (IMHO). More tests with different settings.
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