The following lists the key points about the use of BIMMeasure Measurement Rules.
When do they get used?
When measuring by dragging and dropping objects from the Model Contents tree or from within the Drawing Viewer or using the Model Contents 'Add to Measurement' option where you are relying on the system 'pulling in' the required measurement value from the Property data within the drawing or model file (as shown in the Properties panel).
For all other methods of measuring within BIMMeasure you have control over which value is measured and therefore do not need the rules.
How do they work?
Each Rule has a Selection Criteria which the system uses to see if there is a property of the object being measured that matches the criteria.
For example, does the object being measured have a property called '_type' with a value of 'ifcWall'?
If Yes, search the property data for the Measurement property defined in the Rule and use that value as the measurement value.
For example, for a Measurement Type of Area, get the value associated with the 'NetSideArea' property and use it as the measured value in the Measurements grid.
What happens if the Selection Criteria are not met?
If the object being measured does not have the property named in the Selection Criteria. For example, there is not a property called '_type' with a value of 'ifcWall', the following sequence occurs:
Use each of the Selection Criteria in the order. If none are found then search the property data of the object for the keyword properties;'Area', 'Length', 'Volume' depending on the measurement type. If found, use the associated value, if not found use the physical or graphical properties of the object to derive the measurement value.
What happens if the Measurement Property does not exist?
If, having matched the Selection Criteria it is found that none of defined Measurement Properties exist, e.g. there is not a property called 'NetSideArea', the following sequence occurs:
Search each of the Measurement Properties in order. If none are met then search the property data of the object for the keyword properties;'Area', 'Length', 'Volume' depending on the measurement type. If found, use the associated value, if not found use the physical or graphical properties of the object to derive the measurement value.
What is the process for Creating the Rules?
The process is to create Rules and then populate the Rule Sets with the Rules.
Rules can have multiple Selection Criteria. i.e., If first Selection Criteria is not met then try the next and if that is not met try the next and so on. For this reason they should be placed in a specific to less specific order so that the last Selection Criteria is a 'catch all' should none of the others be present.
Multiple Selection Criteria can be used together or separately by setting an AND or OR flag on the Selection Criteria following the previous one.
For the actual measurements multiple, alternative Properties can be defined to retrieve the measurement value. I.e. if the first defined Property to use for the measurement value does not exist try the next and it that does not exist try the next and so on. For this reason the Measurement Properties should be placed in a specific to less specific order so that the last Property is a 'catch all' should all the others not exist. Should this Property not exist then the system checks for basic keywords and then physical properties as described elsewhere.
In many cases, to avoid get spurious measurement values if there are no defined properties on an object, it may be best to have a special Measurement Property of: (Exclude Physical). This will prevent system from generating a value from the graphical components and instead return a value of zero (0).
What drawing file and model formats can Measurement Rules be applied to?
· AutoCAD .dwg format
· .dwf or dwf(x) format, both 2D Sheets and 3D Models
· .ifc format
· .pdf and other raster file formats can not used in conjunction with Measurement Rules, the items displayed on the drawing do not have individual properties.
The Rules feature cannot be used with a CADMeasure licenced system
A CADMeasure licenced system can read measurements created via Rules in a BIMMeasure licenced system. However a CADMeasure system cannot use any Rules within the session to create measurements, only BIMMeasure licenced systems can use Rules.
Rule Sets and Rules can be saved to BIMMeasure Templates for use with other sessions
Rule Sets and Rules created in a BIMMeasure Session can be saved to a Template .cmt file for use on other sessions. At any point, select menu: File > Save Session As... and set the Save as type to be Session Template (*.cmt) and navigate to the location to save the template. Please ensure that any drawings/models and measurements have been removed before saving as a template.