Celestia Forums

Hi

What is the unit of measurement of a coordinate value (e.g the values of the x y z of a vertex) in cmod models? Is it kilometer or just meter? or else?

Joe,

A CMOD doesn't have any units of scale AFAIK. ie. it has a scale of 1.
The scale of the object is finally determined by the values you attribute to the mesh in the SSC file.
(Using the directives NormalizeMesh and MeshScale, or Radius. see: http://en.wikibooks.org/wiki/Celestia/SSC_File#MeshScale_scaleFactor)

Generally, for simple models, just specifying a Radius is sufficient, and the Mesh is scaled automatically.

CC

CC

Umm, you're right and Celestia agrees with what you said. But my engineering inertia makes me think distance be gauged in light-year, astromomy-unit, kilometer, or metter--especially when I display a cmod model's size in a celx script, it is helpful to show the measurement unit.

Do you mean the "internal" coordinates of the CMOD? They are degrees (spherical projection) around a center which is the unity (1). Thus the distances of such coordinates to the center (radius) can be whatelse unity of measure every positive real number different from zero carry on (meter, inch and they multiples). Of course inches must be convert to meters for the use within SSC/CELX.