I'm having an output quality problem with ParametricPlot3D in Mathematica 7. I need to show a complicated curve found by numerical integration of a differential equation (using NDSolve), and export the curve's graphic (from ParametricPlot3D) to PDF, so I can use it in another application. I know how to do it, and it's working, but the curve is having a very crude aspect (straight lines, instead of a smooth curve, or some parts of the curve aren't right). Of course, I could add the option PlotPoints-> 5000 to smooth the curve (4000 or less isn't enough, apparently), but this gives a huge PDF file (about 10 MB for a simple vectorial graphic), and it's useless for what I need to do with it. The exact same code in Mathematica 4 (which I don't have access anymore) didn't gave me the problem at all : I got a nicely looking curve which could be exported into a small PDF file. So I don't understand what is happening here with Mathematica 7. Do I need to add some special directives to the ParametricPlot3D, to get an optimised smooth curve, without having to add something like PlotPoints -> 5000 ?