
The Limits of Human Vision
Michael F. Deering
Sun Microsystems
ABSTRACT
A model of the perception limits of the human visual system is presented, resulting in an esti-
mate of approximately 15 million variable resolution pixels per eye. Assuming a 60 Hz stereo
display with a depth complexity of 6, we make the prediction that a rendering rate of approxi-
mately ten billion triangles per second is sufficient to saturate the human visual system. 17 dif-
ferent physically realizable computer display configurations are analyzed to understand their
visual perceptions limits. The displays include direct view CRTs, stereo projection displays,
multi-walled immersive stereo projection displays, head-mounted displays, as well as standard
TV and movie displays for comparison. A theoretical maximum triangle per second rate is also
computed for each of these display configurations.
Keywords: Visual Perception, Image quality, virtual reality, stereo displays, immersive projec-
tion displays, fishtank stereo.
1INTRODUCTION
With improvements in 3D graphics technology we are on the brink of producing hardware that
matches or exceeds the needs of the human visual system. This fact must now be taken into
account when designing 3D graphics hardware. As part of an effort to design future hardware
and display systems, a study was made of the rendering impact of matching 3D rendering ca-
pability to the known limits of the human visual system.
While real-time 3D computer graphics has historically traded off image quality and resolution
to meet frame rate and cost constraints, this is becoming less and less the case. The ultimate
limits of human visual perception must now be included in hardware trade-offs. A model of
such visual limits will be developed, and illustrated in terms of several common display devic-
es. Combined with other rendering assumptions, an estimated theoretical bounds on the maxi-
mum triangle rendering rate needed to saturate the human visual system will be made.
2 Limits of Human Vision
The eventual consumer of all 3D rendering is the human visual system. With display technol-
ogy and real-time hardware rendering speeds ever increasing, we are on the threshold of a gen-
eration of machines that will surpass the visual system’s input capabilities. On a machine with
a single user and a sustained render frame rate of 60 Hz, even present day CRTs exceed the
maximum spatial frequency detection capability of the visual system, in regions away from
where the fovea is looking. To take advantage of this situation, a hardware rendering architec-
ture could implement some form of variable resolution frame buffer. In such a frame buffer,
the spatial resolution is not fixed, but must be per-frame programmable to match the variable-
resolution nature of human vision. It is assumed that such pixels must be antialiased, and that
the antialiasing filter’s frequency cut-off must also vary dynamically to match the local effec-
tive pixel density. An important question is to understand the precise quantitative details of the
variable resolution frame buffer configurations necessary to match the variable resolution na-
ture of the human visual system. This section will provide this information in familiar computer