Surface plots

IDL> window,0,retain=2
IDL> surface,z,x,y 
; OR
IDL> surface,z,x,y,charsize=2.5,xtitle='East',ytitle='North',ztitle='Alt.'

Black on white instead of white on black:

IDL> surface,z,x,y,charsize=2.5,xtitle='East',ytitle='North',$
ztitle='Alt.',color=0,background=16777215

Using default colour table:
color=0 is black
color 256*256*256-1=16777215 is white

IDL> print,256*256*256
      0                     ;answer is wrong because of short integers
IDL> print,256l*256*256
    16777216

``color'' and ``background'' are keywords (i.e. optional)