3d heatmap in R, outline the hot spots -

i'm making 3d heatmap using rgl package in r , thinking outlining hot spot areas. want make map following 1 (you can note there solid boundary around hot spots.): image 1

with data, can make looks one.image 2. don't know how draw outline in 3d environment. datasets 2 images different. want visualization way similar previous one. need draw outlines.

thanks suggestions.

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