A head-mounted three dimensional display*
`
`by IVAN E. SUTHERLAND**
`
`The University of Utah
`Salt Lake City, Utah
`
`INTRODUCTION
`
`The fundamental idea behind the three-dimensional
`display is to present the user with a perspective image
`which changes as he moves. The retinal image of the real
`objects which we see is, after all, only two-dimensional.
`Thus if we can place suitable two-dimensional images on
`the observer's retinas, we can create the illusion that
`he is seeing a three-dimensional object. Although stereo
`presentation is important to the three-dimensional illu(cid:173)
`sion, it is less important than the change that takes
`place in the image when the observer moves his head.
`The image presented by the three-dimensional display
`must change in exactly the way that the image of a real
`object would change for similar motions of the user's
`head. Psychologists have long known that moving per(cid:173)
`spective images appear strikingly
`three-dimensional
`even without stereo presentation; the three-dimensional
`display described in this paper depends heavily on this
`"kinetic depth effect."1
`In this project we are not making any effort to mea(cid:173)
`sure rotation of the eyeball. Because it is very difficult
`to measure eye rotation, we are fortunate that the per(cid:173)
`spective picture presented need not be changed as the
`user moves his eyes to concentrate on whatever part of
`the picture he chooses. The perspective picture presented
`need only be changed when he moves his head. In fact,
`we measure only the position and orientation of the op(cid:173)
`tical system fastened to the user's head. Because the op(cid:173)
`tical system determines the virtual screen position and
`
`*The work reported in this paper was performed at Harvard
`University, supported in part by the Advanced Research Proj(cid:173)
`ects Agency (ARPA) of the Department of Defense under con(cid:173)
`tract SD 265, in part by the Office of Naval Research under con(cid:173)
`tract ONR 1866(16), and in part by a long standing agreement
`between Bell Telephone Laboratories and the Harvard Computa(cid:173)
`tion Laboratory. The early work at the MIT Lincoln Laboratory-
`was also supported by ARPA.
`
`**Formerly of Harvard University
`
`the user's point of view, the position and orientation of
`the optical system define which perspective view is
`appropriate.
`Our objective in this project has been to surround the
`user with displayed three-dimensional information. Be(cid:173)
`cause we use a homogeneous coordinate representa(cid:173)
`tion,2-3 we can display objects which appear to be close
`to the user or which appear to be infinitely far away. We
`can display objects beside the user or behind him which
`will become visible to him if he turns around. The user
`is able to move his head three feet off axis in any direc(cid:173)
`tion to get a better view of nearby objects. He can turn
`completely around and can tilt his head up or down
`thirty or forty degrees. The objects displayed appear
`to hang in the space all around the user.
`The desire to surround a user with information has
`forced us to solve the "windowing" problem. The "clip(cid:173)
`ping divider" hardware we have built eliminates those
`portions of lines behind the observer or outside of his
`field of view. It also performs the division necessary to
`obtain a true perspective view. The clipping divider can
`perform the clipping computations for any line in about
`10 microseconds, or about as fast as a modern high-per(cid:173)
`formance display can paint lines on a CRT. The clip(cid:173)
`ping divider is described in detail in a separate paper4
`in this issue. Because the clipping divider permits
`dynamic perspective display of
`three-dimensional
`drawings and arbitrary magnification of two-dimen(cid:173)
`sional drawings, we feel that it is the most significant
`result of this research to date.
`In order to make truly realistic pictures of solid
`three-dimensional objects, it is necessary to solve the
`"hidden line problem." Although it is easy to compute
`the perspective positions of all parts of a complex ob(cid:173)
`ject, it is difficult to compute which portions of one
`object are hidden by another object. Of the soft(cid:173)
`ware solutions now available,2,5-10 only the MAGI9
`and the Warnock10 approaches seem to have poten(cid:173)
`tial as eventual real-time solutions for reasonably com-
`
`757
`
`Niantic's Exhibit No. 1012
`Page 001
`
`

`

`758
`
`Fall Joint Computer Conference, 1968
`
`plex situations; the time required by the other methods
`appears to grow with the square of situation complexity.
`The only existing real-time solution to the hidden line
`problem is a very expensive special-purpose computer
`at NASA Houston11 which can display only relatively
`simple objects. We have concluded
`that showing
`"opaque" objects with hidden lines removed is beyond
`our present capability. The three-dimensional objects
`shown by our equipment are transparent "wire frame"
`line drawings.
`
`Operation of the display system
`
`In order to present changing perspective images to
`the user as he moves his head, we have assembled a wide
`variety of equipment shown in the diagram of Figure 1.
`Special spectacles containing two miniature cathode ray
`tubes are attached to the user's head. A fast, two-dimen(cid:173)
`sional, analog line generator provides deflection signals
`to the miniature cathode ray tubes through transis(cid:173)
`torized deflection amplifiers. Either of two head position
`sensors, one mechanical and the other ultrasonic, is used
`to measure the position of the user's head.
`As the observer moves his head, his point of view
`moves and rotates with respect to the room coordinate
`system. In order to convert from room coordinates to a
`coordinate system based on his point of view, a transla(cid:173)
`tion and a rotation are required. A computer uses the
`measured head position information to compute the ele(cid:173)
`ments of a rotation and translation matrix appropriate
`to each particular viewing position. Rather than chang(cid:173)
`ing the information in the computer memory as the user
`
`S
`
`3-0 LINE
`SPECIFICATION
`IN ROOM
`COORDINATES
`
`MATRIX
`MULTIPLIER
`
`3-D LINE
`SPECIFICATION
`"
`IN EYE
`COORDINATES
`
`CLIPPING
`DIVIOER
`
`2-0 LINE
`SPECIFICATION
`IN SCOPE ~H
`"
`COORDINATES
`
`ANALOG
`DISPLAY
`DRIVER
`
`FIGURE 1—The parts of the three-dimensional display system
`
`moves his head, we transform information from room
`coordinates to eye coordinates dynamically as it is dis(cid:173)
`played. A new rotation and translation matrix is loaded
`into the digital matrix multiplier once at the start of
`each picture repetition. As a part of the display process
`the endpoints of lines in the room coordinate system are
`fetched from memory and are individually transformed
`to the eye coordinate system by the matrix multiplier.
`These translated and rotated endpoints are passed via
`an intermediate buffer to the digital clipping divider.
`The clipping divider eliminates any information out(cid:173)
`side the user's field of view and computes the appropriate
`perspective image for the remaining data. The final out(cid:173)
`puts of the clipping divider are endpoints of two-di(cid:173)
`mensional lines specified in scope coordinates. The two-
`dimensional line specifications are passed to a buffered
`display interface which drives the analog line-drawing
`display.
`We built the special-purpose digital matrix multiplier
`and clipping divider to compute the appropriate per(cid:173)
`spective
`image dynamically because no available
`general-purpose computer is fast enough to provide a
`flicker-free dynamic picture. Our equipment can pro(cid:173)
`vide for display of 3000 lines at 30 frames per second,
`which amounts to a little over 10 microseconds per line.
`Sequences of vectors which form "chains" in which the
`start of one vector is the same as the end of the previous
`one can be processed somewhat more efficiently than
`isolated fines. Assuming, however, two endpoints for
`every line, the matrix multiplier must provide coordi(cid:173)
`nate transformation in about 5 microseconds per end-
`point. Each matrix multiplication requires 16 accumu(cid:173)
`lating multiplications; and therefore a throughput of
`about 3,000,000 multiplications per second. The clip(cid:173)
`ping divider, which is separate and asynchronous,
`operates at about the same speed, processing two end-
`points in slightly over 10 microseconds. Unlike the fixed
`time required for a matrix multiplication, however, the
`processing time required by the clipping divider de(cid:173)
`pends on the data being processed. The time required
`by the analog line generator depends on the length of
`the line being drawn, the shortest requiring about 3
`microseconds, the longest requiring about 36 micro(cid:173)
`seconds and an average of about 10 microseconds.
`The matrix multiplier, clipping divider, and fine-
`generator are connected in a "pipe-line" arrangement.
`Data "stream" through the system in a carefully inter(cid:173)
`locked way. Each unit is an independently timed digital
`device which provides for its own input and output
`synchronization. Each unit examines an input flag
`which signals the arrival of data for it. This data are
`held until the unit is ready to accept them. As the unit
`accepts a datum, it also reads a "directive" which tells it
`what to do with the datum. When the unit has accepted
`
`Niantic's Exhibit No. 1012
`Page 002
`
`

`

`A Head-Mounted Three Dimensional Display
`
`759
`
`a datum, it clears its input flag. When it has completed
`its operation, it presents the answer on output lines and
`sets an output flag to signal that data is ready. In some
`cases the unit will commence the next task before its
`output datum has been taken. If so, it will pause in the
`new computation if it would have to destroy its output
`datum in order to proceed. Orderly flow of information
`through the system is ensured because the output flag of
`each unit* serves as the input flag of the next. The aver(cid:173)
`age rate of the full system is approximately the average
`rate of the slowest unit. Which unit is slowest depends
`on the data being processed. The design average rate is
`about 10 microseconds per line.
`The computer in this system is used only to process
`the head-position sensor information once per frame,
`and to contain and manipulate the three-dimensional
`drawing. No available general-purpose computer would
`be fasl enough to become intimately involved in the per(cid:173)
`spective computations required for dynamic perspec(cid:173)
`tive display. A display channel processor serves to
`fetch from memory the drawing data required to recom(cid:173)
`pute and refresh the CRT picture. The channel proces(cid:173)
`sor can be "configured" in many ways so that it is also
`possible to use the matrix multiplier and clipping
`divider independently. For example, the matrix multi(cid:173)
`plier can be used in a direct memory-to-memory mode
`which adds appreciably to the arithmetic capability of
`the computer to which it is attached. For two-dimen(cid:173)
`sional presentations it is also possible to bypass the ma(cid:173)
`trix multiplier and provide direct input to the clipping
`divider and display. These facilities were essential for
`debugging the various umts independently.
`
`Presenting images to the user
`
`The special headset which the user of the three-di(cid:173)
`mensional display wears is shown in Figure 2. The opti(cid:173)
`cal system in this headset magnifies the pictures on each
`of two tiny cathode ray tubes to present a virtual image
`about eighteen inches in front of each of the user's eyes.
`Each virtual image is roughly the size of a conventional
`CRT display. The user has a 40 degree field of view of
`the synthetic information displayed on the miniature
`cathode ray tubes. Half-silvered mirrors in the prisms
`through which the user looks allow him to see both the
`images from the cathode ray tubes and objects in the
`room simultaneously. Thus displayed material can be
`made either to hang disembodied in space or to coincide
`with maps, desk tops, walls, or the keys of a typewriter.
`The miniature cathode ray tubes mounted on the
`optical system form a picture about one half of an inch
`square. Because they have a nominal six tenths mil
`spot size, the resolution of the virtual image seen by the
`user is about equivalent to that available in standard
`
`FIGURE 2—The head-mounted display optics
`with miniature CRT's
`
`large-tube displays. Each cathode ray tube is mounted
`in a metal can which is carefully grounded to protect the
`user from shorts in the high voltage system. Additional
`protection is provided by enclosing the high voltage
`wiring in a grounded shield.
`The miniature cathode ray tubes have proven easy to
`drive. They use electrostatic deflection and focussing.
`Because their deflection plates require signals on the
`order of only 300 volts, the transistorized deflection am(cid:173)
`plifiers are of a relatively straightforward design. Com(cid:173)
`plementary-symmetry emitter followers are used to
`drive four small coaxial cables from the amplifier to
`each cathode ray tube. Deflection and intensification
`signals for the miniature cathode ray tubes are derived
`from a commercial analog line-drawing display which
`can draw long lines in 36 microseconds (nominal) and
`short lines as fast as three microseconds (nominal).
`The analog line generator accepts picture information
`in the coordinate system of the miniature cathode ray
`tubes. It is given two-dimensional scope coordinates for
`the endpoints of each line segment to be shown. It con(cid:173)
`nects these endpoints with smooth, straight lines on the
`two-dimensional scope face. Thus the analog line-draw(cid:173)
`ing display, transistorized deflection amplifiers, minia(cid:173)
`ture cathode ray tubes, and head-mounted optical sys(cid:173)
`tem together provide the.ability to present the user with
`any two-dimensional line drawing.
`
`Head position sensor
`
`The job of the head position sensor is to measure
`and report to the computer the position and orientation
`of the user's head. The head position sensor should pro-
`
`Niantic's Exhibit No. 1012
`Page 003
`
`

`

`760 Fall Joint Computer Conference, 1968
`
`vide the user reasonable freedom of motion. Eventually
`we would like to allow the user to walk freely about the
`room, but our initial equipment allows a working
`volume of head motion about six feet in diameter and
`three feet high. The user may move freely within this
`volume, may turn himself completely about, and may
`tilt his head up or down approximately forty degrees.
`Beyond these limits, head position cannot be measured
`by the sensor. We suspect that it will be possible to ex(cid:173)
`tend the user's field of motion simply by transporting
`the upper part of the head position sensor on a ceiling
`trolley driven by servo or stepping motors. Since the
`position of the head with respect to the sensor is known,
`it would be fairly easy to keep the sensor approximately
`centered over the head.
`The head position measurement should be made with
`good resolution. Our target is a resolution of 1/100 of
`an inch and one part in 10,000 of rotation. Resolution
`finer than that is not useful because the digital-to-ana(cid:173)
`log conversion in the display system itself results in a
`digital "grain" of about that size.
`The accuracy requirement of the head position sensor
`is harder to determine. Because the miniature cathode
`ray tubes and the head-mounted optical system to(cid:173)
`gether have a pin-cushion distortion of about three per-
`
`FIGURE 4—The ultrasonic head position sensor in use
`
`cent, information displayed to tbe user may appear to
`be as much as three tenths of an inch out of place. Our
`head position sensor, then, should have an accuracy on
`the order of one tenth of an inch, although useful per(cid:173)
`formance may be obtained even with less accurate head-
`position information.
`We have tried two methods of sensing head position.
`The first of these involves a mechanical arm hanging
`from the ceiling as shown in Figure 3. This arm is free to
`rotate about a vertical pivot in its ceiling mount. It has
`two universal joints, one at the top and one at the bot(cid:173)
`tom, and a sliding center section to provide the six
`motions required to measure both translation and ro(cid:173)
`tation. The position of each joint is measured and pre(cid:173)
`sented to the computer by a digital shaft position en(cid:173)
`coder.
`The mechanical head position sensor is rather heavy
`and uncomfortable to use. The information derived
`from it, however, is easily converted into the form
`needed to generate the perspective transformation. We
`built it to have a sure method of measuring head posi(cid:173)
`tion.
`We have also constructed a continuous wave ultra(cid:173)
`sonic head position sensor shown in Figure 4. Three
`transmitters which transmit ultrasound at 37, 38.6, and
`
`FIGURE 3—The mechanical head position sensor in use
`
`Niantic's Exhibit No. 1012
`Page 004
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`

`

`A Head-Mounted Three Dimensional Display
`
`761
`
`CRYSTAL OSCILLATORS -
`
`6 - B IT COUNTER -
`
`^*l I I I I Krl I.I I I I KfrTT-TT-TV
`
`FIGURE 5—The ultrasonic head position sensor logic
`
`40.2 kHz are attached to the head-mounted optical sys(cid:173)
`tem . Four receivers are mounted in a square array in the
`ceiling. Each receiver is connected to an amplifier and
`three filters as shown in Figure 5, so that phase changes
`in sound transmitted over twelve paths can be measured.
`The measured phase shift for each ultrasonic path can
`be read by the computer as a separate five-bit number.
`The computer counts major changes in phase to keep
`track of motions of more than one wavelength.
`Unlike the Lincoln Wand12 which is a pulsed ultra(cid:173)
`sonic system, our ultransonic head position sensor is a
`continuous wave system. We chose to use continuous
`wave ultrasound rather than pulses because inexpensive
`narrow-band transducers are available and to avoid con(cid:173)
`fusion from pulsed noise (such as typewriters produce)
`which had caused difficulty for the Lincoln Wand. The
`choice of continuous wave ultrasound, however, intro(cid:173)
`duces ambiguity into the measurements. Although the
`ultrasonic head position sensor makes twelve measure(cid:173)
`ments from which head-position information can be de(cid:173)
`rived, there is a wave length ambiguity in each of the
`measurements. The measurements are made quite pre(cid:173)
`cisely within a wave, but do not tell which wave is being
`measured. Because the wavelength of sound at 40 kHz
`in air is about 1/3 of an inch, each of the twelve mea(cid:173)
`surements is ambiguous at 1/3 inch intervals. Because
`the computer keeps track of complete changes in phase,
`the ambiguity in the measurements shows up as a con(cid:173)
`stant error in the measured distance. This error can be
`thought of as the "initialization error" of the system.
`It is the difference between the computer's original
`guess of the initial path length and the true initial path
`length.
`We believe that the initialization errors can be re(cid:173)
`solved by using the geometric redundancy inherent in
`
`making twelve measurements. We have gone to consid(cid:173)
`erable effort to write programs for the ultransonic head
`position sensor. These programs embody several tech(cid:173)
`niques to resolve the measurement ambiguities. Al(cid:173)
`though we have had some encouraging results, a full
`report on the ultrasonic head position sensor is not yet
`possible.
`
`The perspective transformation
`
`Generating a perspective image of three dimensional
`information is relatively easy. Let us suppose that the
`information is represented in a coordinate system based
`on the observer's eye as shown in Figure 6. If the two-
`dimensional scope coordinates, Xs and Ya, are thought
`of as extending from — 1 to + 1, simple geometric reason(cid:173)
`ing will show that the position at which a particular
`point should be displayed on the screen is related to its
`position in three-dimensional space by the simple rela(cid:173)
`tions:
`
`Xs = — cotan-
`z'
`2
`
`v'
`a
`Y„ — — cotan-
`z'
`2
`If an orthogonal projection is desired, it can be obtained
`by making the value of z' constant. Because the per(cid:173)
`spective (or orthogonal) projection of a straight line in
`three-dimensional space is a straight line, division by
`the z' coordinate need be performed oply for the end-
`points of the line. The two-dimensional analog lihe-
`
`FIGURE 6—The x' y', z' coordinates system based on the
`observer's eye position
`
`Niantic's Exhibit No. 1012
`Page 005
`
`

`

`762
`
`Fall Joint Computer Conference, 1968
`
`generating equipment can fill in the center portion of a
`three-dimensional line by drawing a two-dimensional
`line. The digital perspective generator computes values
`only for the endpoint coordinates of a line.
`The three-dimensional information to be presented
`by the three-dimensional display is stored in the com(cid:173)
`puter in a fixed three-dimensional coordinate system.
`Because this coordinate system is based on the room
`around the user, we have chosen to call it the "room"
`coordinate system. The drawing data in the room coor(cid:173)
`dinate system is represented in homogeneous coordi(cid:173)
`nates. This means that each three-dimensional point
`or end of a three-dimensional line is stored as four* se(cid:173)
`parate numbers. The first three correspond to
`the
`ordinary X Y and Z coordinates of three-dimensional
`space. The fourth coordinate, usually called W, is a scale
`factor which tells how big a value of X Y or Z represents
`a unit distance. Far distant material may thus easily
`be represented by making the scale factor, W, small.
`Infinitely distant points are represented by setting the
`scale factor, W, to zero, in which case the first three co(cid:173)
`ordinates represent only the direction to the point.
`Nearby points are usually represented by setting the
`scale factor, W, to its largest possible value, in which
`case the other three coordinates are just the familiar
`fixed-point representations of X Y and Z.
`
`The matrix multiplier
`
`We have designed and built a digital matrix multi(cid:173)
`plier to convert information dynamically from the fixed
`"room" coordinate system to the moving "eye" coordi(cid:173)
`nate system. The matrix multiplier stores a four-by-four
`matrix of 18 bit fixed-point numbers. Because the draw
`ing data are represented in homogeneous coordinates,
`the single four-by-four matrix multiplication provides
`for both translation and rotation.2 The matrix multi(cid:173)
`plier accepts the four 18 bit numbers which represent an
`endpoint, treating them as a four-component vector
`which it multiplies by the four-by-four matrix. The
`result is a four-component vector, each component of
`which is truncated to 20 bits. The matrix multiplier de(cid:173)
`livers this 80 bit answer to the clipping divider in ap(cid:173)
`proximately 5 microseconds. It
`therefore performs
`about three million scalar multiplications per second.
`The matrix multiplier uses a separate multiplier
`module for each column. Each module contains an ac(cid:173)
`cumulator, a partial product register, storage for the
`four matrix elements in that column, and the multipli(cid:173)
`cation logic. The entries of a row of the matrix serve
`simultaneously as four separate multiplicands. An in(cid:173)
`dividual component of the incoming vector serves as
`the common multiplier. The four multiplications for a
`
`single row are thus performed simultaneously. For
`additional speed, the bits of the multiplier are examined
`four at a time rather than individually to control multi(cid:173)
`ple-input adding arrays.
`
`The clipping or windowing task
`
`The job of the clipping divider is to accept three-
`dimensional information in the eye coordinate system
`and convert it to appropriate two-dimensional end-
`points for display. If both ends of the line are visible,
`the clipping divider needs merely to perform four divi(cid:173)
`sions, one for each two-dimensional coordinate of each
`end of the line. Enough equipment has been provided in
`the clipping divider to perform these four divisions
`simultaneously.
`If the endpoints of a line are not within the observer's
`field of view, the clipping divider must decide whether
`any portion of the line ig within the field of view. If so,
`it must compute appropriate endpoints for that portion
`as illustrated in Figure 7. Lines outside the field of view
`or behind the user must be eliminated. Operation of the
`clipping divider is described in a separate paper4 in this
`issue.
`Like the matrix multiplier, the clipping divider is an
`independently-timed digital device which provides for
`its own input and output synchronization. It has an in(cid:173)
`put and an output flag which provide for orderly flow of
`information through the clipping divider. If a line lies
`entirely outside the field of view, the clipping divider
`will accept a new input without ever raising its output
`flag. Thus only the visible portions of lines that are all
`or partly visible get through the clipping divider.
`
`SCOPE COORDINATES
`
`EYE COORDINATES
`
`Ys= -J-VSy+VCy
`
`FIGURE 7—Clipping and perspective projection
`in three dimensions
`
`Niantic's Exhibit No. 1012
`Page 006
`
`

`

`A Head-Mounted Three Dimensional Display
`A
`
`763 "H-
`
`FIGURE 8—A computer-displayed perspective view of the
`cyclo-hexane molecule
`
`Results
`
`I did some preliminary three-dimensional display ex(cid:173)
`periments during late 1966 and early 1967 at the MIT
`Lincoln Laboratory. We had a relatively crude optical
`system which presented information to only one of the
`observer's eyes. The ultransonic head position sensor
`operated well enough to measure head position for & few
`minutes before cumulative errors were objectionable.
`The coordinate transformations and perspective com(cid:173)
`putations were performed by software in the TX-2. The
`clipping operation was not provided: if any portion of a
`line was off the screen, the entire line disappeared.
`Even with this relatively crude system, the three
`dimensional illusion was real. Users naturally moved to
`positions appropriate for the particular views they
`desired. For instance, the "size" of a displayed cube
`could be measured by noting how far the observer must
`move to line himself up with the left face or the right
`face of the cube.
`Two peculiar and as yet unexplained phenomena oc(cid:173)
`curred in the preliminary experiment. First, because the
`displayed information consisted of transparent "wire(cid:173)
`frame" images, ambiguous interpretations were still
`possible. In one picture a small cube was placed above a
`larger one giving the appearance of a chimney on a
`house. From viewpoints below the roof where the
`"chimney" was seen from inside, some concentration
`was required to remember that the chimney was in fact
`further away than the building. Experience with physi(cid:173)
`cal objects insisted that if it was to be seen, the chimney
`must be in front.
`A second peculiar phenomenon occurred during the
`display of the bond structure of cyclo-hexane as shown
`in Figure 8. Observers not familiar with the rippling
`hexagonal shape of this molecule misinterpreted its
`shape. Because their view of the object was limited to
`certain directions, they could not get the top view of the
`molecule, the view in which the hexagonal shape is most
`clearly presented. Observers familiar with molecular
`shapes, however, recognizedthe object as cyclo-hexane.
`In more recent experiments with the improved optical
`system and vastly improved computation capability,
`two kinds of objects have been displayed. In one test, a
`"room" surrounding the user is displayed. The room is
`shown in Figure 9 as it would look from outside. The
`room has four walls marked N, S, E, and W, a ceiling
`marked C and a floor marked F. An observer fairly
`quickly accommodates to the idea of being inside the
`displayed room and can view whatever portion of the
`room h6 wishes by turning his head. In another test a
`small cube was displayed in the center of the user's
`operating area. The user can examine it from whatever
`side he desires.
`
`FIGURE 9—A computer-displayed perspective view of the
`"room" as seen from outside
`
`The biggest surprise we have had to date is the favor(cid:173)
`able response of users to good stereo. The two-tube opti(cid:173)
`cal system presents independent images to each eye. A
`mechanical adjustment is available to accommodate to
`the different pupil separations of different users. Soft(cid:173)
`ware adjustmeots in our test programs also permit us to
`adjust the virtual eye separation used for the stereo
`computations. With these two adjustments it is quite
`easy to get very good stereo presentations. Observers
`capable of stereo vision uniformly remark on the realism
`of the resulting images.
`
`Niantic's Exhibit No. 1012
`Page 007
`
`

`

`764
`
`Fall Joint Computer Conference, 1968
`
`ACKNOWLEDGMENT
`
`When I started work on the head-mounted display I
`had no idea how much effort would be involved. The
`project would have died many times but for the spirit
`of the many people who have become involved. The
`ultrasonic head-position sensor was designed and built
`at the MIT Lincoln Laboratory by Charles Seitz and
`Stylianos Pezaris and is available for our continued use
`through the cooperation of Lincoln Group 23. Seitz, as a
`Harvard employee, later designed the matrix multi(cid:173)
`plier. Robert Sproull, a most exceptionally capable
`Harvard Senior, simulated, designed most of, built
`parts of, and debugged the clipping divider. Two gradu(cid:173)
`ate students, Ted Lee and Dan Cohen have been an es(cid:173)
`sential part of the project throughout. Our many argu(cid:173)
`ments about perspective presentation, clipping, hid(cid:173)
`den-line algorithms, and other subject? form one of the
`most exciting educational experiences I have had. Ted
`Lee's programs to display curved surfaces in stereo have
`been the basis for many experiments. Cohen's programs
`to exercise the entire system form the basis of the dem(cid:173)
`onstrations we can make. I would also like to thank
`Quintin Foster who supervised construction and debug(cid:173)
`ging of the equipment. And finally, Stewart Ogden, so
`called "project engineer," actually chief administrator,
`who defended us all from the pressures of paperwork so
`that something could be accomplished.
`
`REFERENCES
`
`1 BF G R E EN JR
`Figure coherence in the kinetic depth effect
`Journal of Experimental Psychology Vol 62 No 3 272-282 1961
`2 LG ROBERTS
`Machine perception of three-dimensional solids
`M IT Lincoln Laboratory Technical Report No 315 May 22
`1963
`3 LG ROBERTS
`Homogeneous matrix representation and manipulation
`
`of N-
`
`(Thesis)
`
`computer-drawn
`
`dimensional constructs
`The Computer Display Review Adams Associates May 1965
`4 RF SPROULL IE SUTHERLAND
`A clipping divider
`Proceedings of the Fall Joint Computer Conference 1968
`this issue
`5 D COHEN
`A program for drawing bodies with the hidden lines removed
`A term-project for course 6.539 M IT Fall 1965
`6 H T H A Y N ES
`A computer method for perspective drawing
`Master's Thesis Texas A&M University Aug 1966
`7 P L O U T R EL
`A solution
`to the hidden-line problem for
`polyhedra
`New York University Technical Report 400-167
`Bronx New York September 1967
`8 A A P P EL
`The notion of quantitative invisibility and the machine rendering
`of solids
`Proceedings of 22nd National Conference ACM
`ACM Publication p 67 Thompson Book Company Washington
`DC 1967
`9 Mathematical Spplications Group Inc (MAGI)
`3-D simulated graphics
`Datamation February 1968
`10 J E WARNOCK
`A hidden line algorithm for halftone picture representation
`University of Utah Technical Report 4-5 May 1968
`11 Equipment installed at the Manned Space Craft Center at
`Houston Texas. The project is under the direction of the
`General Electric Company Electronics Laboratory under
`NASA Contract No NAS 9-3916
`12 LG ROBERTS
`The Lincoln wand
`M IT Lincoln Laboratory Report June 1966
`13 A C TRAUB
`Stereoscopic display using rapid varifocal mirror oscillations
`Applied Optics Vol 6 number 6 June 1967
`14 P VLAHOS
`The three-dimensional display: Its cues and techniques
`Journal of the Society for Information Display Vol 2 Number
`6 Nov/Dec 1965
`15 R LAND IE S U T H E R L A ND
`Real time color stereo computer displays
`To be published in Applied Optics
`
`Niantic's Exhibit No. 1012
`Page 008
`
`