Use the 
Object Merge surface node to grab geometry from other objects' geometry networks. This is useful for various purposes:
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Create piecemeal objects with subsets of an “overall” object’s geometry. For example, you can model a car all in one network, then create separate objects with the moving parts of the car for purposes of animation.
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You can also do the reverse, model parts separately and merge them together into one object.
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By importing points from two objects, you can create a new object that connects them that will work as the referenced objects move. For example, to animate a rope that a character uses to swing across a chasm, you could import points from the character’s hand and the rope attachment point, and model the rope between them.
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Object Merge is sometimes useful because it “bakes” transforms on the imported geometry (see the discussion of the Transform object parameter in the steps below).
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Anywhere else you might want to use geometry from another object, either for display or just to use its points for reference.
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Go to the Geometry level of the object into which the geometry will be merged.
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Use the tab menu to create an
Object Merge node. -
In the Object Merge node’s parameters, Use the merge list to choose the geometry to merge in.
You can also manually type the path to an object or SOP node, use wildcards to merge in multiple objects, use a bundle reference to merge in all objects in a bundle, use a dynamics path to merge in geometry from a dynamics simulation, and more. See the help for the
Object Merge node for more information on the Object n parameter. -
The node’s Transform object parameter is very important. It affects the transformation of the geometry as it is imported.
Warning
Never animate an object containing Object Merges. Parent the object to a Null and animate the Null.
Warning
The “show one/all” setting affects the orientation of the imported geometry in the viewer.
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When show all (show the entire scene) is on, the viewer shows geometry relative to the world origin.
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When show one (show only the current object) is on, the viewer shows geometry relative to the current object’s origin.
Because geometry imported by Object Merge is positioned by its source object, not the current object, switching between show one and show all might make imported geometry appear to move in the viewer.