Dealing with unit conversions

[daniel_temple]

Hello!

Our US based studio has recently started trying to incorporate Phoenix FD into more scenes. Invariably our biggest issue is scale. Everything is modeled correctly (I've read Svetlin's posts on this and fully understand the volcano example, etc etc.), but in order to properly handle Revit or SketchUp files from american architects we have to have our system units set to either Feet or Inches during the import process. Just given our import workflow we can't really change that, otherwise we end up with objects that were transformed and don't play well with certain plugins etc.

We have tried:

1 - Working with the scene leaving units at feet or inches, but end up with giant foam bubbles that look like golf balls and weird simulation. I've tried the 'scale' option and modifying foam size multiplier manually, but it just leads to heartache.
2 - Changing the scene units to CM, but of course that gives you a mis-scaled scene
3 - Opening a fresh scene, setting to CM, and merging in a scene and choosing to re-scale. This still ends up with strange simulation, perhaps because of the XForm history to the geometry?
4 - Opening a fresh scene, setting to CM, and opening a new scene and choosing 're-scale' on the units dialogue. This gives similar results to option #3.

All in all we've spent a ton of manhours trying to sort this. Is there a clean solution? Or might you ever consider either providing Presets we could load that would factor in that scale change? Or automating this in a future version? It's turned into a bit of a time suck for us, sorry if we're being obtuse. For what it's worth if we start a blank scene and do a simple simulation with system units set to CM everything works as it should.

Thanks for your time,
Daniel

[phil_gibson]

Hi,

Try the:- PhoenixFDFire:- "Grid/Scene Scale" settings:- ( Liquid should be the same. )

I found this confusing to start with, as different sample tutorials seem to hop around using different scales with no uniformity. This would not work for us, we need to keep it the same as we always use.
So to sort it out I just kept my scenes "Unit Setup" the same as we always have it. "Display Unit Scale" is theoretically irrelevant. Made a Fire Explosion Simulation at the size I needed in the scene and ran the Simulation at different "Scales" starting from way too small, then getting x10 bigger in measurement every time. PhoenixFDFire:- "Grid/Scene Scale" settings, from very small ( <1.0 ) to very big ( >10.0+ ).
NOTE:- Changing the "Scene Scale" changes the X,Y,Z dimensions shown on the left. ( Not the adjustable "Grid" figures.) So here you can see the X,Y,Z dimensions that Phoenix is using. e.g. 10" / 100" / 1000".
It was quite a dramatic difference in the results. A small scale showed it was a small explosion with low intensity and detail, as you'd expect. Increasing in size to a large explosion with high intensity and detail.
The important thing is everything in the scene is the same, no Scale changes to the model or file. Just the PhoenixFDFire "Grid/Scene Scale" settings.

I hope this helps you find the "Scale" you need.

Phil.

[daniel_temple]

Thanks for the tip! I thought I had read to 'avoid' using that feature, but it does seem to work well! Coming from feet as the system units I did 0.03 for Scene Scale. The only other thing I had to change was the bubble size multiplier to 0.03 as well and it seems 'about right.' Still not sure if there's a better way...wish this was automated or at least prompted in some way. Thanks again for the help!!