Formula Syntax

The formulas available for use in Model Map definitions and object-based Dimension Group properties are generally based on the functions and formulas used in Excel^®.

Properties

To retrieve the value of a property from a BIM object, the property name must be enclosed in square brackets. For example:

[Width] retrieve the value of the Width property of the measured BIM object.

To use only a specified number of characters from the property, use the LEFT or RIGHT function. The left function specifies the number of characters to use from the left side of the property, and the right function specifies the number of characters to use from the right side, as shown below. The first parameter is the property in square brackets and the second is the number of characters.

LEFT([Category],20) RIGHT([Family Name],20)

If the same property name exists with multiple categories, an exclamation mark can be used to separate the category and name in the property specification:

[Profile!Construction] retrieves the value of the Profile property in the Construction category

[Profile!Identity Data] retrieves the value of the Profile property in the Identity Data category

[Start Date!Construction] retrieves the value of the Start Date property in the Construction category

On rare occasions, the same property name can exist under multiple paths in the BIM data. Slashes can be used to specify the correct point in the BIM hierarchy for the desired property value:

[\\IfcWall\Plaster\NetVolume] retrieves the NetVolume specified against IfcWall\Plaster on the BIM object

[\\IfcWall\Brickwork Clay\NetVolume] retrieves the NetVolume specified against IfcWall\Brickwork Clay on the BIM object.

Literal text can be included in the expression by enclosing it in double quotes. If the text already has a double quote (”), place a second double quote in front of it.

For example: “Marble” would result in Marble.

“Faux “”Travertine””” would result in Faux “Travertine”.

Supported Functions and Operators

Operators: /, *, +, -, (, ), <, >, <=, >=, OR, AND, !=, TRUE, FALSE, “” for strings, [] for properties.

Functions: LEFT (), RIGHT (), IF (), XNUMBER()

ADVANCED MANUAL 3D Measurement and BIM Quantities Worked Examples

To retrieve the value of a property from a BIM object, the property name must be enclosed in square brackets. For example:

[Type Name] retrieve the value of the Type Name property – would give

“Plain”

Extracted numerical quantities are always converted into the appropriate building units as they are extracted from the BIM objects. For example, suppose the example object is being used in a building that uses metres as its Base UOM:

If we were to extract the Height Offset from Level property, it would be converted from the millimetre value stored in the object property, to a metre value, which matches the building unit.

[Height Offset from Level] retrieve the value of the Height Offset from Level property – would give “3 m”

ADVANCED MANUAL 3D Measurement and BIM Quantities If no unit is specified in the BIM property value, the values specified in the drawing properties are used as the default units for the quantities. Suppose the drawing is configured as follows:

If we retrieve the value of the Volume property, which has no units included in the property value, it will assume that the value is in Cubic Metres as set in the drawing properties (also see 6.5 above):

[Volume] retrieve the value of the Volume property of the measured BIM object – would give “1.94 m³”.

Properties Including Categories

In the sample properties for the wall shown above, the Name property exists in both the “Concrete Precast 200 200” and “IfcWallStandardCase” categories. We can no longer just say [Name], as this doesn’t make it clear which of the two Name properties we want to use. To differentiate between them, an exclamation mark can be used to separate the category and name in the property specification.

[IfcWallStandardCase!Name] retrieves the value of the Name property in the IfcWallStandardCase category

[Concrete Precast 200 200!Name] retrieves the value of the Name property in the Concrete Precast 200 200 category

ADVANCED MANUAL 3D Measurement and BIM Quantities Combining Properties

In many cases, none of the properties contain the required values, but a calculation using one or more properties can be used to get the required value. CostX^® supports the four basic arithmetic operators: +, -,

*, and /, as well as brackets ().

Example 1

For example, suppose we want the area of the door with the properties as shown above. To calculate the area of the door, we need get the product of the height and the width. To do this, we need to use a formula that multiplies the properties together:

[Height]*[Width]

Each property will be evaluated, and then the resulting quantities multiplied together to give the final answer (assuming the building is being worked in metres):

[Height]*[Width] → 2.4m * 5.1m → 12.24m2

The formula to be used for the area is therefore [Height]*[Width], which gives a resulting quantity of 12.24m2.

Example 2

The properties for the duct above don’t give a height for the duct. We can calculate this from the object properties by subtracting the Bottom Elevation from the Top Elevation. To do this, we need to use a formula:

[Top Elevation] - [Bottom Elevation]

Once again, each property will be evaluated, and the final value calculated. This will work as follows, again assuming the building is using metres:

[Top Elevation] – [Bottom Elevation] → 3.6575m - 3.4075m → 0.25m

ADVANCED MANUAL 3D Measurement and BIM Quantities Example 3

Consider another duct. In this case, we want to know the external height of the duct. The object properties do provide us with a height; however, this height is the interior height of the duct and the thickness of the duct is not provided by any of the available object properties. The only way for us to determine the exterior height is to divide the area by the length. This can be done using the following formula:

[Area] / [Length]

The steps CostX uses to determine the value of this formula, working in metres, are:

[Area] / [Length] → 6.946210101268 m2 / 4.961578644 m

→ 1.399999999933 m Example 4

Suppose we want to calculate the perimeter of the ceiling tile in use with the fire sprinkler whose

properties are shown above. To do this, we need to add twice the length to twice the width of the tile. The formula for calculating this is as follows:

2*[NDY_Ceiling Tile Length]+2*[NDY_Ceiling Tile Width]

→ 2*0.6m+2*0.6m → 2.4m Or alternatively:

2*([NDY_Ceiling Tile Length]+[NDY_Ceiling Tile Width])

→ 2*(0.6m+0.6m) → 2.4m

Each gives a resulting quantity of 2.4m in a building that uses metres as the building unit.

ADVANCED MANUAL 3D Measurement and BIM Quantities