Scene Scale

[Otuama]

Hi all.

We work in meter scale.

Every time I try to use tyFlow in meter scale it's always a nightmare.  I tried to fill a bowl ( for example: 15cm/0.15m diameter) with particles... didn't work. They were giving odd behaviour or weren't filling at all.

Now I'm testing a cloth on a table it's being a pain. Getting some odd results.

We're an archviz company so have always used meter scale. We use it in both system and display. I'm aware that simulating often works best in cm scale.

I was concerned when we started using PhoenixFD but making scaling adjustments to the settings fixes that and we have no problems. It seems that this isn't possible with tyFlow though 

Is there something I'm missing for working in meter scale?

It'd be great if someone can help with this. I'd ideally not have to work in cm and then find a way to convert to m scale.

Thanks,

Sean

[tyFlow]

No part of tyFlow has any dependency on unit scale or unit type. You can work in any scale or unit type that you want.

You'll have to be more specific about what's not working for you.

[Otuama]

No part of tyFlow has any dependency on unit scale or unit type. You can work in any scale or unit type that you want.

You'll have to be more specific about what's not working for you.

Hi, thanks for the reply.  

What I'll do is create a scene in both scales sometime tomorrow.

I just opened a second Max, set the display and system scale to cm.

I the recreated the scene with the same dimensions.  For example, a box in the meter scale scene is 1.9m...... in the cm scale scene is 190cm.

The cm scene is working much better already.

I'll save these scenes where they are and recreate them tomorrow... maybe I'm just tired   .

I'll then send the scenes if I'm still having issues, if that's ok?

Thanks again,

Sean

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Oh, one more thing.... I think I'm in love with tyFlow.

I've been wanting to use it for ages and am working a funky breakdown video for a job we did... And wanted to incorporate tyFlow somewhere.

Here's my first tyFlow test   .

[tyFlow]

If you're using PhysX, you may have just forgotten to adjust the default gravity strength. tyFlow isn't internally dependent on units...but which unit type you choose will affect the strength of forces each time step. Beside the default gravity spinner there is a little [>] box you can click that will set the value to real-world based on your units of choice.

[Otuama]

Hi.

Sorry for not replying sooner.

I've finally gotten round to doing some tests.  Maybe get yourself a coffee 

I created a table cloth scene in both metre & centimetre scales.  I created them from scratch (didn't merge anything into max etc). 

I actually found out something when testing..... if you type, 0.1m into a centimetre scale scene, it actually converts the values   .  I had no idea.

I have included the scenes here, I'd be grateful if someone could have a look:  Max Scenes


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I think I know where I was somewhat going wrong last time, which has led me to more questions and have a feeling there's an underlying issue with the thought that tyFlow can be used in metre and centimetre scene scales without issues.

This is the issue I was having a few days ago.  All I was trying to do is have a cloth twirl with a tyVortex node



It's the Thickness value of the CUDA collision solver.



Even though the scene is set to metres, tyFlow values don't adapt to the scene scale by default.

When I put a value of 0.001m into the box, it sorted that odd issue

However, it still remains the case that all values in tyFlow, even though a scene is in meter scale, the default values are unchanged from the centimetre versions.

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Back to the table cloth scene.

I spent a while trying to get this to work.  All values that I changed in one scene I also converted in another.

However, back to the issue above; a lot of values are still using the default ones, but when using metre scane, Max sees the values as being a lot bigger than they should be.

For example:

CUDA collision solver > Self-collisions > Self thickness

Default value = 0.1cm
In meter scale it's 0.1m (10cm)

Here's the results of table test.  Even though I changed values to match/convert in both scene scales, there are still a lot of default values I haven't touched.

METER SCALE
30 Frames = 10 mins



CENTIMETRE SCALE
30 Frames = 34 seconds



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What would be great is if tyFlow automatically converted default values to adapt to scene scales because it'd be insanity to convert every single value in the scene.

But I can imagine how much of a headache that'd be.

And some default values are 0.05cm, which converts to 0.0005m.  The lowest Max goes down to is 0.001

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I hope at least some of this makes sense.

We need to keep with metre scale scenes so I'm trying to think of a workaround.

I'll bring up the topic of switching to centimetre scale with the office tomorrow.

We did it once but for some reason needed to switch back.

Many thanks!!!

Sean

[tyFlow]

Units in max are purely aesthetic properties for spinners. Everything internally is calculated without any specific unit (ie, calculated with generic units). Some parts of max may indeed convert units if you import different unit types, but tyFlow does not do any of that (at least, not internally)...so if you design a setup in cm and then import into a scene in miles you may need to manually convert, yes.

The discrepancy in your sim timings is due to the vastly different behavior due to force scale (which it seems you deduced already). Dropping cloth at 1cm/frame will involve a lot less collisions than dropping it down at 1m/frame or what not. If you import cm values and don't convert properly to meters...everything will be different.

Max goes down to full float precision (much more than 4 decimal places)...you just need to increase spinner precision in your max settings.