Using a Custom Unit in Revit

[mathieu.p78]

Is it possible to create a 'Custom Unit' in Revit?

We are working with a custom unit in Rhino (shaku, a traditional Japanese measure unit, 1shaku=0.303030303Meters, 1shaku=11.93032689 inches).

We are developing a Rhino.Inside. Revit workflow and have a need of showing shaku as an 'alternate unit' in Revit.

The original Rhino model is always going to be created in shaku but eventually both shaku and imperial units need to be shown on the architectural sheet set.

When we opened the Rhino model in Rhino.Inside.Revit we where prompted to either convert to feet-inches or "continue using shaku".

When we continue to use shaku there is no problem with opening the file however when we open Grashopper we get the following warning "Model Unit Mismatch Warning".

[mhiserZFHXS]

I don't think its possible to make your own units. What exactly is the purpose of using this alternate unit? Is it the process, AKA are you meant to be actually using it as you work on your model? Or do you just need the end result of showing it on a schedule? If you just need to show it in the end, I'd just build the model using imperial, and then use formulas to convert imperial units to the shaku units.

[mathieu.p78]

The ability to use shaku is essential during the design and modelling process. The ability to use shaku is so critical that it guides the entire workflow.

Could you tell me more about using formulas to convert units. Do you have a resource on the subject?

[mhiserZFHXS]

If the point is to use the units as you work, then I think you're out of luck in Revit. Someone else can chime in if I'm wrong. The formulas would only help on schedules at the end.

I guess another option could be to just model it with imperial units. If something is 1 shaku, model it as 1 foot. As long as everything is modeled this way, I don't think it'd be an issue. But I do mean everything. Just scale anything you import appropriately. This way you could just add suffixes to your dim lines, schedules or whatever will show units.

[HVAC-Novice]

Modeling in some scale with artificial units would be very bad practice and would go against what Revit stands for - to model exactly the way it will be built. 

Even if this was a good idea, you have to change all families etc. Doors, windows etc. You would also be in conflict with standardized elements (i.e. drywall sheet sizes in certain increments, doors)

And why does anyone outside the US use IP units? I thought Japan is metric. I kind of understand the use of an ancient unit like shaku (well, not really). But why IP units? 

Looks like a shaku is about 1ft. 

If the building is small enough, just use IP units and pretend it is Shakun. 

[ToanDN]

Not familiar with Rhino.Inside.Revit but if you link 3DM in Revit, choose Feet for Import Units, then select the link, Edit Type, and change Scale Factor to 0.994193.

[brianorser]

Hello @mhiserZFHXS 

I am working with Mathieu on this implementation. Could you tell us more about how we can go about creating formulas to make the unit conversion in tables, dimension labels, etc? This is a good backup option if in fact, as you say, we are out of luck.

Thanks for your time.

Best

Brian

[mathieu.p78]

Pretending 1 foot = 1 shaku is not an option. Accuracy is critical as you understand.
The question is not why we would use Imperial units or a traditional Japanese unit instead the question should be why a simple conversion within Revit and the use of an alternate custom unit is not a standard function.
The screenshot shows the options that are built in in Rhino as a comparison. I certainly hope the development team will pick up on that.

Even Lightyears is an option in Rhino....

[carl-marcus.ekstromDDJLJ]

Hi. I would create a custom dimensioning family starting from the line based detail item template. Then you can display whatever units you want. If you need help creating this family, post a picture of how you want the dimensions to be displayed on sheet. 

[HVAC-Novice]

I'm sure implementing an ancient unit, that no one is using anymore, will be top priority for the development team. 

[mhiserZFHXS]

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@mathieu.p78 wrote:

Pretending 1 foot = 1 shaku is not an option. Accuracy is critical as you understand. I don't see why it wouldn't be an option. Its a digital model, not a real life object. As long as everything is scaled the same, it will look correct.

The question is not why we would use Imperial units or a traditional Japanese unit instead the question should be why a simple conversion within Revit and the use of an alternate custom unit is not a standard function. Because Revit is meant for construction. Its really not meant for whatever kind of project this is. I'm starting to wonder if you are using the correct tool for your project.

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