# Waterfall and large robot sim

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Hello everyone!

So I have a small issue I've been working through trial and error through and found some pretty interesting results and am trying to get some feedback on how best to approach the problem of scale.

Below is a video of a robot coming out of a waterfall.  You might say I kind of want this to be Pacific Rim type, the robot is huge, about 200 feet tall/61 meters and the waterfall is a little taller

So in troubleshooting this I found there were at least 3 parameters that need to be set:  gravity, density, and spatial scale.  There are probably more but I haven't encountered them yet.   Changing the units in the preferences before putting down the nodes will automatically set these.

Another way I'm attempting to resolve this is by actually scaling the objects up to actual size to see how it goes.

I'm also trying a different method that was suggested to me...modifying the scale time parameter on the dop net.

I've been looking through the forums to see how others have approached this issue, but I'm coming up a bit short.

Does anyone have any useful methods of approaching a large scale simulation like this?

Edited by ntkirby
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Scale everything up so it fits the dimensions you want. 1 unit in Houdini is 1 meter.

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In relation to scale I looked at this video:

61 meters would be 610 units if I went by that video...

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In relation to scale I looked at this video:

61 meters would be 610 units if I went by that video...

I have no idea what that is, and I haven't watched it. But if they they say that 610 units = 61 meters, thats false. 61 units = 61 meters.

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what they guy in the video says is kinda correct... he just forgets that all objects come in on a normalized grid of 0-1...
so teapot and box should be same scale.
The character is in animation scale so one unite one centimeter or 10 centimeters to make value tweaking easier and more obvious.

but as far as simulations go one unite == 1meter.
and that is that.

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And just like Juri and Skybar said scale it up to be a proper scale, As for the Waterfall i would also recommend adding an air field into the waterall sim. I find when you start pushing to larger scales having this air system in the fluid solver really adds to the motion and feel or the sim!

Cheers

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Here's what it looks like in proper scale..

Robot is about 61 meters (units) high

https://vimeo.com/97347816

Nice little spashes here and there, lots from the robot though so I'll have to slow that part down

Edited by ntkirby
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Cool sim, the scaling change looks a lot bigger IMO.   Whitewater !

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yeah scale works much better now.
and I dont think you should slow down the interaction part... I mean it is a giant robot walking through a waterfall.... sooo you would kind expect that:D
would be cool to see how it looks when you use a nother flip sim instead of white water.. and then add white water sim with pops on top of that.

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yeah scale works much better now.

and I dont think you should slow down the interaction part... I mean it is a giant robot walking through a waterfall.... sooo you would kind expect that:D

would be cool to see how it looks when you use a nother flip sim instead of white water.. and then add white water sim with pops on top of that.

I'd love to see an example of using a flip to drive a more detailed flip fluid that sounds like a functional flip upres

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well it is not really driving on as I think you think it might.
Its more like building a one of system.
one big sim...
that goes over ever state water can be in, going from the big waves down to smaller ones, to whitewater and then mist.
all in one sim all in one go.... sounds crazy and it kinda is, but if you know micro solvers in can be really quite fast:D
faster sometimes then to write out on sim do the emission calculations on there and then sim that.
Since the micro solvers are so fast with volumes and calculations on them that it is faster then to do it in more then one step.
and since it is all Geo based in the dops you can just isolate any of the parts in the sim after wards when you dont like that particular sim and just read the emission groups and fields from the cached sim instead of dops.
So this set up gives you the best of both worlds.

The file only shows the basics.. there is no feedback blending (particles just die) and no whitewater and no mist.
but that should be easy to set up.

Hope it helps a bit.
Cheers,
Juri

FlipUpres.01.hip

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well it is not really driving on as I think you think it might.

Its more like building a one of system.

one big sim...

that goes over ever state water can be in, going from the big waves down to smaller ones, to whitewater and then mist.

all in one sim all in one go.... sounds crazy and it kinda is, but if you know micro solvers in can be really quite fast:D

faster sometimes then to write out on sim do the emission calculations on there and then sim that.

Since the micro solvers are so fast with volumes and calculations on them that it is faster then to do it in more then one step.

and since it is all Geo based in the dops you can just isolate any of the parts in the sim after wards when you dont like that particular sim and just read the emission groups and fields from the cached sim instead of dops.

So this set up gives you the best of both worlds.

The file only shows the basics.. there is no feedback blending (particles just die) and no whitewater and no mist.

but that should be easy to set up.

Hope it helps a bit.

Cheers,

Juri

*mind explodes*   Such a cool setup to even try to decode and mess with.   Thanks Juri!

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well it is not really driving on as I think you think it might.

Its more like building a one of system.

one big sim...

that goes over ever state water can be in, going from the big waves down to smaller ones, to whitewater and then mist.

all in one sim all in one go.... sounds crazy and it kinda is, but if you know micro solvers in can be really quite fast:D

faster sometimes then to write out on sim do the emission calculations on there and then sim that.

Since the micro solvers are so fast with volumes and calculations on them that it is faster then to do it in more then one step.

and since it is all Geo based in the dops you can just isolate any of the parts in the sim after wards when you dont like that particular sim and just read the emission groups and fields from the cached sim instead of dops.

So this set up gives you the best of both worlds.

The file only shows the basics.. there is no feedback blending (particles just die) and no whitewater and no mist.

but that should be easy to set up.

Hope it helps a bit.

Cheers,

Juri

Really cool setup.

Thanks.

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• 1 year later...

Really cool setup.

Thanks.

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