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This button fits the daemons bounding sphere to the dimensions of an object. By clicking on this button, a node browser appears where you can select one item. Automatically adjusted daemons always have a small cache around the reference object. You can also adjust the daemon's sphere' with the "Scale" and "Position" parameters of the → "Node" panel or the R and W keys.
Fit to scene
For the calculation of the daemon’s bounding sphere, RealFlow takes all scene elements into consideration.
Radius
This is the sphere's size in metres.
Inverse
With "No", particles will be removed inside the volume, with "Yes", this happens outside.