Model Checks for Revit Project Coordinates

Recently, a customer had a question on how to validate project coordinates using the Model Checker for Revit add-in. And indeed, the Model Checker can check the parameter values in the properties of the Survey Point and Project Base Point. However, the Revit API doesn't make it as straightforward as it could be. The following tips will help you create checks to consistently validate the project coordinate values.

Install the RevitLookup Add-in

According to its creator, Jeremy Tammik, the RevitLookup add-in is an "interactive Revit RFA and RVT project database exploration tool to view and navigate BIM element parameters, properties and relationships". The add-in is an essential tool for understanding what aspects of the Revit API can be accessed and how they can be validated by model checks.

You can download the installation file here: GitHub - jeremytammik/RevitLookup: Interactive Revit RFA and RVT project database exploration tool to view and navigate BIM element parameters, properties and relationships.

For more information on the Revit API, check out Jeremy Tammik's blog: The Building Coder (typepad.com)

Validate the "AsDouble" Value

For the parameters in the Survey Point and Project Base Point, the "AsValueString" value is what we see in the properties and expressed in the Length unit format that is established in the Project Units settings. But the model check can only validate the "AsDouble" value, which will always be the same value regardless of the unit format needed for the project (i.e. "Feet and Fractional Inches", "Feet", "Millimeters", etc.). This is to ensure proper computations and functionality in the model based on a single, consistent format.

In the example below, the N/S, E/W, and Elev parameters for the Project Base Point are shown in "Feet and Fractional Inches" format.

However, by using the RevitLookup add-in, we can discover that the “AsDouble” value for the N/S parameter is formatted in decimal feet.

To create a check for the N/S parameter, the “AsDouble” value should be input, either pre-defined in the check from the Model Checker Configurator or as a user-defined input from the Setup section in the Model Checker.

Other Tips

1. Create a separate check for each Survey Point and Project Base Point parameter. Combining all of the parameters together can potentially create false pass/fail results.
2. Keep the Validation field set to “None” in order to accurately input the “AsDouble” value.
3. Add the entire “AsDouble” value. While the value might display as rounded, the check requires the full numeration.
4. The “AsDouble” value for Lat and Long for Survey Point and Angle to True North for Project Base Point are based on radians, as shown in the example below for Angle to True North.

5. A set of checks for Survey Point and Project Base Point parameters can be found in the “Revit Model Best Practices” checksets available in the Model Checker Public Library.