Scene Scale for Archviz

[Otuama]

Hi all,

We've always worked in meters but are considering thinking about considering switching to cm for a number of reasons.

One of my reasons being I find working with simulation plugins much easier in cm scale.

Can anyone think of any issues with doing this, considering we work with large scene for archviz?

Thanks

[James Vella]

If you use real-world measurements for tileable textures then yes they will be out of scale when you merge them.

Also your modifiers that use scene units will also be out of scale.

Many things will go bonkers, but easiest way to check is create a scene in cm, merge things in and check. Some things will be fine, others wont. Check which matters most to your workflow.

If its only for simulations then why not just work in cm for those scenes and then bake them down or import them into your scene at the correct scale (in your case, meters)?

[Otuama]

Hi, yeah we need to test whether switching things up will screw up our pipeline.

We don't tend to have 'use real-world texture coordinates' on in preferences as sometimes have issues with that.

Any modifiers we use that depend on scene units (shell & chamfer for example) I think we may find it better in cm because we need to enter very small values usually.

I can't really think of any modifiers we use where we'd have an issue.

When it comes to simulations, I find Phoenix ok in meter scale but have a lot of issues with tyFlow, especially when following tutorials.

90% of tyFlow tutorials I've seen are in cm.  I've had to set my precision to 5 decimals in order to fine tune stuff.

I've scaled things simmed in cm up to meters before and although it works fine it's not ideal.

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I think the obvious outcome from me bringing it up is to test the sodding thing in an actual job.  :D

[Aram Avetisyan]

Hi,

if you mean system scale, I have used cm it, by gut feeling, and it has been fine. Not to say that other units have been problematic, absolutely not. If you know how and when to use system units, anything is fine. I think I have found other software using CM by default more than any other units (but still they worked fine with others and conversions). So if there is any I would suggest - go with cm.

If you mean the display units - then it is mm in most of the cases. This is because all architectural drawings/documents (except US I guess) have measurements specified in mm, and you just read the numbers and input, without thinking about decimals.

[danio1011]

I'm from the US so I use ft and\or inches for display units.  But I recently switched from 'inches' to 'cm' in system scale and I've found PhoenixFD to be way easier to handle.  Even though it has a parameter for scene scale I never really found it to be global (affecting foam size etc).  When using CM everything just looks much more natural out of the box.

Just my personal experience but I'm very happy being on CM in system units now.  I don't regularly use TyFlow FWIW.

[burnin]

Just a pro-tip for pleasant interoperability I learned along the way:

To prevent any unit, orientation & color issues make yourself an intermittent 'I/O scene' (kind of a 'triage') set to your own standard.

[James Vella]

Display scale makes no difference at all. You can change this at any point to m, cm, mm etc wont do anything strange to the scene. I was refering to changing the system units. I also use CM for system units, I agree with danio1011 most things just seem to be easier overall for small scenes and aerials without the z-fighting.

Also I should clarify more what I mean about 'realworld' or 'tileable'. If you have any materials that use X/Y coordinates these will change between scenes.

Example mm scene:


Merging the mm scene into cm scene:


Modifier issue:
Chamfer modifier with 0.025cm ends up being 0.25cm

[Tom]

To prevent any unit, orientation & color issues make yourself an intermittent 'I/O scene' (kind of a 'triage') set to your own standard.

That looks interesting but I don't get 100% what you mean. Can you explain a bit?

[dzintas]

General rule of thumb for system scale I think is, if distance from 0.0.0 is:
0m-10m - millimeters, for modeling furniture or other knick knacks.
10m-100m - centimeters, single family house with a reasonable plot of land.
100m-1km - meters, apartment complex and so on.

In general there are no perfect unit scale for every situation, and it should be chosen by project size. I usually just bounce around from centimeters to meters depending on the project.
So if you mostly work on big projects, switching to centimeters will introduce other issues. Mostly viewport problems like zfighting, spastic camera, precision issues when moving objects.
For typing in small values just use centimeter display units. As for tyflow you can work on a smaller scene that uses centimeter system scale, with few interactable objects from main scene. Then cache the animation or export to vray proxy file, for use in big scene.
But of course this is only if you work on big scenes, if your main work are interiors. Your whole team should have been using centimeters all along.