topic Re: Converting from Internal Units to Meters or Millimeters in Revit API 2023 or 2024 in Revit API Forum

Converting from Internal Units to Meters or Millimeters in Revit API 2023 or 2024

hamza_rahahleh9 — Sat, 10 Jun 2023 21:37:46 GMT

Hello,

I'm new to Revit API and facing an issue while trying to convert values from internal units to meters or millimeters in the Revit API. Specifically, when I attempt to modify a parameter by entering a value like 15, I expect it to represent 15 meters. However, the code seems to convert this value to 15 feet, which is equivalent to approximately 4.572 meters.

I would greatly appreciate any guidance or suggestions on how to correctly convert values from internal units (feet) to meters or millimeters in the Revit API with a class for units. I want to ensure that my parameter modifications are accurately reflected in the desired unit system.

Thank you in advance for your assistance!

attaching a picture explaining what is going on .

Re: Converting from Internal Units to Meters or Millimeters in Revit API 2023 or 2024

jonathan.taVCBM2 — Sun, 11 Jun 2023 07:42:53 GMT

Hi ,

You need to use the UnitUtils class https://www.revitapidocs.com/2023/128dd879-fea8-5d7b-1eb2-d64f87753990.htm .

This explains the change that happened in r2022 well https://archi-lab.net/handling-the-revit-2022-unit-changes/

This also - https://thebuildingcoder.typepad.com/blog/2021/04/pdf-export-forgetypeid-and-multi-target-add-in.html#2

Best , Jonathan

Re: Converting from Internal Units to Meters or Millimeters in Revit API 2023 or 2024

jeremy_tammik — Sun, 11 Jun 2023 08:46:54 GMT

Many thanks to Jonathan for the helpful answer.

Yup, you basically have two choices: DIY or use the official Revit API support.

Personally, I am a fan of DIY and retaining total control (and responsibility). Not always the most efficient way to go, though.

Personally, again, I mostly just have to deal with very simple units, such as the length issue you describe. You can look at The Building Coder samples to see how I handle it there for various situations:

https://github.com/jeremytammik/the_building_coder_samples

Specifically, the Util class includes a region for Unit handling:

https://github.com/jeremytammik/the_building_coder_samples/blob/master/BuildingCoder/Util.cs#L1206-L1411

The main part of interest to you is at the beginning of that region:

private const double _inchToMm = 25.4; private const double _footToMm = 12 * _inchToMm; private const double _footToMeter = _footToMm * 0.001; private const double _sqfToSqm = _footToMeter * _footToMeter; private const double _cubicFootToCubicMeter = _footToMeter * _sqfToSqm; /// <summary> /// Convert a given length in feet to millimetres. /// </summary> public static double FootToMm(double length) { return length * _footToMm; } /// <summary> /// Convert a given length in feet to millimetres, /// rounded to the closest millimetre. /// </summary> public static int FootToMmInt(double length) { //return (int) ( _feet_to_mm * d + 0.5 ); return (int) Math.Round(_footToMm * length, MidpointRounding.AwayFromZero); } /// <summary> /// Convert a given length in feet to metres. /// </summary> public static double FootToMetre(double length) { return length * _footToMeter; } /// <summary> /// Convert a given length in millimetres to feet. /// </summary> public static double MmToFoot(double length) { return length / _footToMm; } /// <summary> /// Convert a given point or vector from millimetres to feet. /// </summary> public static XYZ MmToFoot(XYZ v) { return v.Divide(_footToMm); } /// <summary> /// Convert a given volume in feet to cubic meters. /// </summary> public static double CubicFootToCubicMeter(double volume) { return volume * _cubicFootToCubicMeter; }