How to make the SGI logo

Written by Paul Bourke
November 1992


The SGI logo is generated as follows:
Given two lengths l1 and l2, the "turtle graphics" instructions along with the resulting wire frame result are given below. In what follows, left and right refer to moving towards the negative numbers or positive numbers respectively. Up and down is movement along the z axis, back and forward refer to the y axis.

forward l1
left l2
down l1
right l1
up l2
back l1
down l1
forward l2
left l1
back l1
right l2
up l1
left l1
down l2
forward l1
up l1
back l2
right l1
sgilogo wireframe

In the example above l1 = 1 and l2 = 0.7

Turning the line segments into cylinder/sphere pairs is shown below with its geometric description in Radiance

s cylinder cyl 0 0 7 -0.5 -0.5 0.5 0.5 -0.5 0.5 0.13
s cylinder cyl 0 0 7 0.5 -0.5 0.5 0.5 0.5 0.5 0.13
s cylinder cyl 0 0 7 -0.2 -0.8 -0.8 -0.2 0.2 -0.8 0.13
s cylinder cyl 0 0 7 -0.2 0.2 -0.8 0.8 0.2 -0.8 0.13
s cylinder cyl 0 0 7 0.8 0.2 -0.8 0.8 -0.5 -0.8 0.13
s cylinder cyl 0 0 7 0.8 -0.5 -0.8 0.8 -0.5 0.2 0.13
s cylinder cyl 0 0 7 0.8 -0.5 0.2 0.8 0.5 0.2 0.13
s cylinder cyl 0 0 7 0.8 0.5 0.2 0.8 0.5 -0.5 0.13
s cylinder cyl 0 0 7 0.8 0.5 -0.5 -0.2 0.5 -0.5 0.13
s cylinder cyl 0 0 7 -0.2 0.5 -0.5 -0.2 0.5 0.5 0.13
s cylinder cyl 0 0 7 0.5 0.5 0.5 -0.2 0.5 0.5 0.13
s cylinder cyl 0 0 7 -0.5 -0.5 0.5 -0.5 0.2 0.5 0.13
s cylinder cyl 0 0 7 -0.5 0.2 0.5 -0.5 0.2 -0.5 0.13
s cylinder cyl 0 0 7 -0.5 0.2 -0.5 -0.5 -0.8 -0.5 0.13
s cylinder cyl 0 0 7 -0.5 -0.8 -0.5 -0.5 -0.8 0.2 0.13
s cylinder cyl 0 0 7 -0.5 -0.8 0.2 0.5 -0.8 0.2 0.13
s cylinder cyl 0 0 7 0.5 -0.8 0.2 0.5 -0.8 -0.8 0.13
s cylinder cyl 0 0 7 0.5 -0.8 -0.8 -0.2 -0.8 -0.8 0.13
s sphere sph 0 0 4 -0.5 -0.5 0.5 0.13
s sphere sph 0 0 4 0.5 -0.5 0.5 0.13
s sphere sph 0 0 4 0.5 0.5 0.5 0.13
s sphere sph 0 0 4 -0.2 0.2 -0.8 0.13
s sphere sph 0 0 4 0.8 0.2 -0.8 0.13
s sphere sph 0 0 4 0.8 -0.5 -0.8 0.13
s sphere sph 0 0 4 0.8 -0.5 0.2 0.13
s sphere sph 0 0 4 0.8 0.5 0.2 0.13
s sphere sph 0 0 4 0.8 0.5 -0.5 0.13
s sphere sph 0 0 4 -0.2 0.5 -0.5 0.13
s sphere sph 0 0 4 -0.2 0.5 0.5 0.13
s sphere sph 0 0 4 -0.2 0.5 0.5 0.13
s sphere sph 0 0 4 -0.5 0.2 0.5 0.13
s sphere sph 0 0 4 -0.5 0.2 -0.5 0.13
s sphere sph 0 0 4 -0.5 -0.8 -0.5 0.13
s sphere sph 0 0 4 -0.5 -0.8 0.2 0.13
s sphere sph 0 0 4 0.5 -0.8 0.2 0.13
s sphere sph 0 0 4 0.5 -0.8 -0.8 0.13
s sphere sph 0 0 4 -0.2 -0.8 -0.8 0.13
sgilogo radiance

sgilogo radiance

The "logo" can be interlinked in each 3D direction, a few cells are shown below

sgilogo linked