Sorry if this seems a bit late, but I want to clarify for a future reference the best answer is not entirely correct.
setFrontClipDistance , - , ,
0,01 (), , - , 10 , , , .
, , setBackClipDistance, 10 (). 1000, 1000 .
, simpleUnivers, - instanced.
SimpleUniverse simpleU = new SimpleUniverse(Your3dCanvasHere);
simpleU.addBranchGraph(YourBranchGroupHere);
simpleU.getViewer().getView().setBackClipDistance(1000);