Bifrost

# 1 15-04-2015 , 08:05 PM

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Join Date: Apr 2015

Posts: 5

Hello! I'm just getting into fluids but I've been testing and reading up on bifrost for about 3 weeks now.

seems like not many people are using bifrost anymore.. but hopefully someone can help..Here's what i got:

the boat is around 2.5 units so thats 2.5 meters to bifrost right? it kinda looks like this is a 2.5 cm boat still when you see how big the blobs of water are..

container - 15x2x20
mvs - .05
transport step - .98
max steps - 5000
droplet threshold - .1
mergeback - .1
surface bandwidth - .1
surface density - 3
voriticity is off
stickyness/bandwidth - .12

meshing:
droplet reveal - 5
surface rad - 1.2
resolution - 2

I just thought I'd post something while I wait for my scratch cache to finish. =p

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# 2 16-04-2015 , 04:17 AM

Technical Director
Join Date: Feb 2004

Posts: 2,988

Take a look at "Real-world Units and Scale" in the documentation here: https://knowledge.autodesk.com/suppor...2995C-htm.html

Imagination is more important than knowledge.

Last edited by NextDesign; 17-04-2015 at 06:14 AM.

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# 3 16-04-2015 , 06:13 PM

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Join Date: Apr 2015

Posts: 5

Thanks for the reply!
I did read that documentation before but it seemed like many people with good results ignored keeping the scale the same.
For example this vid:
https://vimeo.com/91709811
- container size was 100x3x30 in cm i assume... so his catamaran should be like 25cm big, however it still looks like its bigger than that.

But aside from that, if I scale my boat up from 2.5 -> 250 units, My container will need to be really large as well. However I doubt I can fill that large a container with mvs-.05 particles. So I'd have to increase mvs ..but wont that just make it the same droplet to boat proportions I have now? - just bigger?

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# 4 17-04-2015 , 02:51 AM

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Join Date: Apr 2015

Posts: 5

I thought I understood this but the more info I find the more I question what I understand..

maya's grid is 1cm default, bifrost sees any unit as 1m
- so if I make a 10x10x10 unit cube in maya, although its cm, Bifrost will take it as 10 m.
If I then make a 1 unit cube to drop inside this 10m bifrost container, bifrost should simulate water to look like i'm dropping a 1 meter cube inside a 10 m pool.

So isn't my boat/container in the proper proportions?
my container is 15x20 meters and my boat is 2.5 meters... I feel like i'm somehow failing basic math here user added image

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# 5 17-04-2015 , 06:11 AM

Technical Director
Join Date: Feb 2004

Posts: 2,988

Sorry, I misunderstood what they were saying. Do you have more detail when you're viewing the voxels directly? Eg, no meshing? Have you tried setting the voxel scale down to see if you get more detail?

Imagination is more important than knowledge.

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# 6 20-04-2015 , 07:31 PM

Registered User
Join Date: Apr 2015

Posts: 5

Hi, no if you mean Do I see more detail using voxels instead of points, - no.

Have I tried scaling down the voxel scale - do you mean the master voxel scale? Its already at .05 I can't go much lower than that without stuff getting weird.

Some buggy things i've noticed is that if my mvs goes too low, I guess it generates too many particles for my gpu to even compute and therefore shows nothing when in points display. Also sometimes I lose the ability to view voxels, I'm thinking i've gone too small in mvs.. but once it breaks, i can never see voxels again. - I'm currently just using points and flipping the mesh on and off. =p

after looking into some other tutorials, I've noticed changing the mesh attributes can help when you can't go smaller in mvs. Surface Radius and Resolution factors seem to let me get some finer looking details. However its really slow modifying these values so I have to be happy with the general motion of the sim first.

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