Hi Guni, Have you taken a look at the SURFACE documentation for IDL yet? I'm not sure exactly what you are trying to do, but I use this quite regularly for 3 dimensional visualizations and I think it might have what you are looking for. Here are a couple of links you might find useful: http://www.exelisvis.com/docs/SURFACE.html http://www.exelisvis.com/...RFACE_Procedure.html https://www.idlcoyote.com/tips/grid_surface.html Thanks, Joe

Hi Joe, Thanks a lot for the info. The links are actually 3d plots where Z is a function/dependent variable. The 3rd link https://www.idlcoyote.com/tips/grid_surface.html helps me, and what I am looking is almost the same with the figure where a set of delaunay triangles are plotted in 2D. I have to create a solid/filled polygon using my X,Y,Z data. In this way I have to plot for more file, and I have to look their trend and etc. But, first of all, I am not able to make a polygon. here is the detail: ---------------------- ;3 indpendent variables x=randomu(seed,100) y=randomu(seed,100) z=randomu(seed,100) ;3d scatter plot p = PLOT3D(x, y, z, 'o' ,/SYM_FILLED,AXIS_STYLE=2,/PERSPECTIVE) ;construct 3d triangulation qhull,x,y,z,triangle,/delaunay,VDIAGRAM=vdiagram,$ VVERTICES=vvertices,connectivity=connectivity ;how to plot the polygon using the returned variables from qhull procedure ? ---------- Thanks, Guni

Sorry Joe, By mistake, I post a report to your reply. My silly mistake, sorry. Actually I thought I am replying. Hope you dont mind. Thanks Guni