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

[hamza_rahahleh9]

 

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 .

[jonathan.taVCBM2]

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.htm...

Best , Jonathan 

[jeremy_tammik · Accepted solution]

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-L...

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;
        }