2.4 Physical Units
Last updated
Last updated
Karamba3D utilizes two sets of physical units:
Internal Calculation and Geometry Input: Units used for internal calculations and reading geometry.
Component Input and Output: Units used for the input and output of Karamba3D components.
These units can be set independently of each other. Changing units via the Karamba3D menu necessitates a recompute of the definition for the updated units-settings to take effect.
Upon installation via the msi-installer, users can specify the family of physical units for input and results. The default option is metric (e.g., meters, centimeters, degrees Celsius, Newtons), but Karamba3D also supports Imperial units (e.g., feet, inches, degrees Fahrenheit, kilopounds).
The units can be changed anytime via the Grasshopper/Karamba3D menu or by editing the “karamba.ini” file (see section 2.3)
Depending on the selected unit family, Karamba3D interprets geometric input as meters or feet by default. The expected physical units for components are displayed in the tooltip that appears when hovering over an input plug.
Karamba3D includes databases for predefined cross-sections and materials, with properties specified in SI units. This also applies to physical constants (e.g., "gravity") defined in the “karamba.ini” file.
Throughout this manual, SI units will be used exclusively for consistency. Any specific differences between using Karamba3D with Imperial and SI units will be mentioned as necessary.
For very small or very large models, default physical units may be impractical. The "karamba.ini" file contains parameters to change the basic physical units used for internal calculations and geometry input from Rhino: "UnitLength", "UnitForce", and "UnitMass" (see Fig. 2.4.1). Possible values for these unit identifiers are listed as comments in the "karamba.ini" file. All input and output values will be converted to and from these units. Units can be mixed, but avoid using both Imperial and SI units simultaneously.
When base units are set to "auto" or "default," the unit system determines the default values.
The basic physical units are for internal bookkeeping and geometry input from Rhino. To change the physical units for input and output, use the "CustomUnits" parameter in "karamba.ini" (see Fig. 2.4.2). This parameter expects a list of comma-separated terms in the format "'original unit'>'custom unit'". If an empty list is provided, the default units apply. These new units apply to all Karamba3D components, and you are free to mix SI and Imperial units as needed.
