The issue of scale defines a fundamental difference between how GIS and CAD systems use coordinate systems. A GIS models the world and the objects in it at a regional or global scale. Conversely, a CAD system is used to model the objects at a scale that is relatively unaffected by the earth's surface. At this scale, design intent and geometric accuracy are the primary focuses of the analysis rather than actual geographic location. Consequently, CAD data is generally smaller in scale than GIS data but capable of high levels of detail.
To accurately place your Revit data in ArcGIS, first determine the units of your Revit files. Then, choose a projection for your scene that matches those units. If your Revit file is in feet, choose an Esri projection file that is also in feet. The elevation units of your layer should match, too; otherwise, your Revit model may appear taller or shorter than it should. Avoid scaling a Revit file because it generally depicts the correct and true form of the structure.
Coordinate systems
The issue of scale defines a fundamental difference between how GIS and BIM use coordinate systems. A GIS models the world and the objects in it at a regional or global scale. Conversely, a BIM is used to model the objects at a scale that is relatively unaffected by the earth's surface. At this scale, design intent and geometric accuracy are the primary focuses of the analysis rather than actual geographic location. Consequently, BIM data is generally smaller in scale than GIS data but capable of high levels of detail.
To accurately place your Revit data in ArcGIS, first determine the units of your Revit files. Then, choose a projection for your scene that matches those units. If your Revit file is in feet, choose an Esri projection file that is also in feet. The elevation units of your layer should match, too; otherwise, your Revit model may appear taller or shorter than it should. Avoid scaling a Revit file because it generally depicts the correct and true form of the structure.
Linear units
Linear units in a BIM file are neither dependent on nor defined by the data's coordinate system; the author determines the drawing units before creating the data.
As a general rule, BIM Files are drawn at full scale (1:1). One drawing unit can represent any linear unit of measure, such as inches, millimeters, meters, or feet. The decision usually rests on the level of detail the model is intended to capture.
Drawing scale
Drawing scale is independent of the Revit model data and generally has no effect on how the data is displayed in ArcGIS Pro. Typically, a mismatch between drawing units and the assigned spatial reference, rather than drawing scale, is the cause of scaling discrepancies encountered in ArcGIS when working with Revit data.