object graphics symbols

[Brad Gom <b_gom(at)hotmail.com>]

I trying to produce a simple 2-d plot with a large number of IDLgrPlot
objects with symbols and no lines.  The problem is that when the symbols
are small, and there are many overlapping plot objects, many of the
symbols disappear. It seems that many of the symbols aren't being
rendered, or are being hidden somehow by overlapping plots.

In direct graphics, if you overplot many plots with just symbols, the
screen just gets more and more dense with pixels. In object graphics, if
I have too many plots, I eventually end up with almost nothing showing
up!

Any ideas as to what is causing this? (or more efficient ways to plot
thousands of possibly overlapping individual dots or symbols in object
graphics?)

Thanks

Brad