I have just started programming in IDL. Before, I have written a tool in Java (using Java3D) that links an image to a 3D plot, representing feature space. Pixels are visualized as small spheres in the 3D plot and a user can rotate the plot and interactively select these small spheres. I was wondering whether thousands of small spheres can be plotted in a 3D IDL plot and whether this can be done fast and efficiently. My second question relates to interaction and selection in 3D in IDL, ie does IDL allow interactive selections of 3D objects? Thanks and regards, Arko