No announcement yet.

Re: Limb Position Measurement

This topic is closed.
  • Filter
  • Time
  • Show
Clear All
new posts

  • Re: Limb Position Measurement


    The following ms. is in press. It pretty much

    >am still working on them. I would greatly appreciate more information
    >with respect to the basic design, cost, weight for the patient,
    >power requirements and electronic and software interfacing of Polhemus
    >and Ascension electromagnetic devives.
    >Where would I find publications on this subject? Thanks for your

    Let me know if you have more specific questions after giving this
    a go through.

    | David Dean, Ph.D., Assistant Professor *********************** |
    | Dept.s Anatomy, Orthodontics, & Biomed Eng. * FAX: (216) 368-3204 * |
    | Bolton-Brush Study, 3080 Bolton Dental Bldg * alternate: 368-8669 * |
    | Case Western Reserve University *********************** |
    | 10900 Euclid Avenue E-mail: |
    | Cleveland, OH 44106-4905 USA Voice: (216) 368-1975 |

    In Press (LA Marcus, ed.): Advances in Morphometrics. NYC:Plenum

    3D Data Capture and Visualization
    David Dean
    Departments of Anatomy, Orthodontics, and Biomedical Engineering
    Case Western Reserve University
    10900 Euclid Avenue
    Cleveland, OH 44106-4905 U.S.A.

    "The next great surge in morphometrics will involve the superb
    new technology of `high-speed workstations."
    Bookstein (1991)

    The hallmark of the New Morphometrics is the use of landmark
    coordinate data. Current computer-based digitization,
    visualization, and analysis applications in morphometrics are
    heavily geared toward 2D (two dimensional) data sets. While some
    organisms are flatter than others, all are three dimensional. We
    are accustomed to conflating these 3D (three dimensional)
    organisms to 2D despite the compromises involved. If coordinates
    are collected from pictorial representations (e.g., photographs,
    x-rays, frame-grabbers, etc.) it is important to attempt to
    register each organism in the same position before image/data
    capture. This is especially true for oblique views. The lateral
    view of bilaterally symmetric organisms is a very popular means
    to represent 3D organisms in 2D. This approach ignores minor, but
    interesting, bilateral asymmetries - a popular topic of
    investigation now. Problems of data capture object registration
    or asymmetry, generally, do not affect the collection of data
    sets in 3D.
    Organisms live in the fourth dimension. It is the task of
    morphometrics to adequately describe 3D organismal variation.
    This variation is due to various 4D processes: ontogeny,
    phylogeny, pathology, injury, or sexual differentiation. Most, if
    not all, 2D morphometric algorithms are easily extended to 3D.
    Until recently three dimensional data capture devices and data
    visualization software have not been readily available. This
    paper discusses the recent profusion of such devices and
    Is it always desirable to undertake three dimensional
    morphometric analyses? There is no single answer to this
    question. Each morphometrician must perform their own
    cost/benefit analysis. As a lure Bookstein (1991) notes that in
    contrast to two-dimensional biological form, three-dimensional
    form may suggest a richness of local and regional geometric
    descriptors that often matches our intuitive sense of how
    biological forms are usefully compared. Thus, while many
    measurements can be made on two dimensional views of or cuts
    through an organism, only the three dimensional surfaces give
    evidence of topology and texture. When possible these important
    biological shape descriptors ought not be ignored.
    The focus of this chapter are tools that assist in the
    analysis of macroscopic biological surfaces and volumes, (e.g.,
    bones, skin, organ systems) that are readily visualized. When not
    visible from the surface often radiological techniques can be
    applied to visualize structures in vivo. It should be mentioned
    that there are a host of problems unique to remote three
    dimensional visualization, especially those related to
    thresholding and isosurface construction, that are not discussed
    here (Fruhauf, 1991; Magnusson et al., 1991).
    Data collection hardware and 3D image reconstruction
    software (i.e., from slice data) for morphometrics needs to have
    a high degree of precision, at least within the acceptable limits
    of direct data capture means such as calipers. There are lots of
    homemade devices (e.g., Corti et al., this volume) that we will
    not discuss here that obtain this level of accuracy. All of these
    devices are used to collect data directly from the surface of the
    study object. When the data are collected indirectly, i.e. by
    scanning, one must have a 3D visualization environment that
    allows quick and precise collection of landmark, surface, and/or
    volumetric data; of course, creating your own visualization
    environment requires a great deal of expertise.
    There are primarily two industrial applications driving the
    development of both direct and remote 3D digitizing devices and
    visualization environments: rapid prototyping and virtual reality
    modeling. Tools developed for rapid prototyping and virtual
    reality visualization have already been put to use in preparing
    fossil reconstructions (Kalvin et al., 1992). Medical imaging
    applications have also been the motivation for many new
    developments in 3D visualization (Coatrieux et al., 1990).
    The following is an annotated listing of 3D data capture and
    visualization hardware and software. I have first hand experience
    with many of the devices and applications discussed below.
    Independent review of each device or package was requested, but
    if not available, summaries were based on product literature:
    caveat emptor. Sections I and II discuss hand operated data
    capture devices and remote laser-light and stereomicroscopic
    surface imaging, respectively. Section III covers a broad range
    of visualization software packages that have morphometric
    applicability. Section IV finishes up with a review of currently
    available rapid prototyping devices also referred to as CAMs
    (Computer-Aided-Manufacturing) or 3D printers.

    Data Capture Devices I: Hand digitization

    These devices are most useful for capturing landmark-point
    and line-tracing coordinate data. However, as compared to the
    scanning devices discussed in Section II, they are not as useful
    for precise capture of surface patches. Radiological slice data
    (e.g., CT and MR) or histological means are the best way to
    gather information on the complete volume. Several of the hand-
    held devices involve a source of electromagnetic radiation which
    creates a field through which a hand-held stylus (sensor) moves.
    The tip of the stylus is tracked as it is applied to an object of
    interest. The location of significant surface features are
    recorded to disk at the operator's instruction.
    These devices are in high demand in human kinematic studies,
    virtual reality applications, or industrial robotic applications,
    activities where three dimensional positional tracking is a
    requirement. Several of these devices are designed to be
    lightweight and portable. Most offer devoted software interfaces
    or can be easily adapted to control/data-recording software run
    from a laptop computer. Several of these devices offer interfaces
    to common CAD programs so that the data can be visualized as it
    is collected. Many of these interfaces allow the user to change
    the point of view, and zoom in and out of the data set. Most
    often the stylus tip controls the point of view, but in some
    interfaces the data lie within a tumbling cube, i.e. you chose
    one of the six faces as a view.
    Multiple viewing options are critical when collecting large
    numbers of points and or line tracings. Visualization becomes
    more and more difficult as the data come to overlie each other.
    When collecting large amounts of data the visual check on
    positional accuracy allows mistakes to be corrected immediately
    rather than discovered at an inopportune time.
    In most cases it is necessary to rigidly secure the object
    being digitized. If more than one view of an object is to be
    digitized (e.g. the part of the object that was anchored in the
    initial digitizing session), it is very helpful to take multiple
    landmarks redundantly between the two session. A Procrustes fit
    can then be done between the landmarks that show no error (i.e.
    throw away landmarks with noise) to match up all the landmark
    data from each view of the object. Several of the various hand-
    held digitizers that produce 3D coordinate data are reported
    below. Unlike laser light or other scanning digitizers, hand-held
    stylus devices have the option for dual use for 2D digitization
    of images.

    Electromagnetic Devices

    1.1 DigiTracker ($3395)
    Visual Circuits
    3309 83rd Avenue North
    Brooklyn Park, MN 55443
    tel (612) 560-6205
    fax (612) 659-6629

    As of this writing the device has not yet been released. An OEM
    version of the Ascension Flock of Birds, it is reported to be a
    work-alike of the Polhemus 3DRAW. Like the Flock of Birds it's
    accuracy rating is a magnitude lower, 0.1" RMS. It may have
    greater utility for biometric applications than an unaltered
    Flock of Birds device, which Visual Circuits retails for $2575,
    because of its well-designed stylus. It is supplied with a
    powerful digitizing software environment, BitBlitzer. A number of
    mainstream Draw, Video, and CAD software export filters are
    supplied with BitBlitzer.

    1.2 Flock of Birds ($2695)
    Ascension Technology Corp.
    P.O. Box 527
    Burlington, VT 05402
    tel (802) 860-6440
    fax (802) 860-6439

    An early split-off from the Polhemus group. The same technology
    has been adapted to tracking multiple electromagnetic 6D (xyz
    coordinates and normals) sensors ("a flock") within the magnetic
    field emitted by a single stationary source. Popular device for
    biomechanical studies of joint movement. Translational accuracy
    rated to 0.1" RMS. Above price is for single sensor device.

    Figure 1. Polhemus 3DRAW: an magnetic source underneath the
    digitizing platform is detected by coils in the stylus. The three
    dimensional position of the stylus tip is reported through a
    serial port to, most probably, a portable computer. An entire
    system, including portable computer, can be assembled that weighs
    less than 20Kg.

    1.3 3DRAW ($6500)
    One Hercules Drive, P.O. Box 560
    Colchester, VT 05446
    tel (800) 357-4777/(802) 655-3159
    fax (801) 655-1439

    This fourth generation device has been used by several
    investigators to study non-human primate and human crania (see
    Dean, this volume; Lele and Richtsmeier, 1992; Corner and
    Richtsmeier, 1992; Richtsmeier and Walker, 1993; Vannier and
    Conroy, 1989). Originally developed to be mounted on a fighter
    pilot helmet to track head movements (Raab et al., 1979), this
    application was soon obsoleted by laser-based sighting devices.
    It consists of a platform under which a fixed 3 axis magnetic
    source is emitted. A specimen can be fixed to the surface of this
    platform. This object is digitized with the aid of a hand-held
    The stylus is equipped with a 3 axis magnetic sensor that
    allows a small computer to determine the location of the tip in 3
    space, including xyz normal information. Because it assumes the
    magnetic field is constant, the work area should be kept
    reasonably clear of ferrous objects. None should be within a
    meter of the digitizing envelope, and other large iron objects
    such as steam heated radiators and filing cabinets should be 2-3
    meters away. Given a changing ferrous environment, the device
    should be recalibrated (it comes with calibration software)
    before each digitizing session. Unless the stylus is used very
    carefully, the normal information is not very important as part
    of the morphometric data collected. However, the viewpoint of the
    data collection interface can be tied to the stylus. This allows
    easy perusal of the data from various points of view, a crucial
    error-checking step whenever potentially overlapping coordinates
    are collected.
    Their is firmware control of the stylus data report; it can
    be set in point or continuous mode on the fly. Continuous mode is
    very useful for tracing edge features (see Dean, this volume).
    The accuracy of this device has been tested internally by
    Polhemus using widely accepted methods (Krieg et al., 1992) and
    has shown accuracy of 0.01" RMS (Root-Mean-Square), or 0.254 mm.
    While this is more than a two-fold improvement over the original
    (first generation) 3SPACE device, the generation of the device
    that has commonly been used with large non-human primate and
    human skull material, it is still below the acceptable range for
    most dental studies.
    The latest version of this device, the 3DRAW, is highly
    portable. The 3DRAW table, stylus, and data handling device all
    together weigh less than 12 pounds. There is a padded, hard-
    shell, airline check-in carrying case available.
    An interface was recently released that allows the data
    collected by this device to be sent to the CADKEYS generic CAD
    program. This flexible PC program can be readily tailored to most
    biometric applications. It is included, gratis, with the device.
    Another longstanding interface for Polhemus, Metrecom, Scientific
    Accessories (see the latter two below) devices is marketed by
    Mira Imaging (2257 South East, Suite 1A, Salt Lake City, UT
    84106, tel. 801/466-4641, fax. 801/466-4699). This interface,
    HyperspaceTM, is primarily aimed at producing a surface mesh of
    solid objects. The NATO morphometrics workshop attendees tested
    this software and found it difficult, but not impossible, to
    adapt to morphometric applications such as single point or space
    curve digitization.

    Laser Light Stylus-based Digitizers

    Figure 2. Laser light digitizer: The stylus emits a light that is
    detected by three non-collinear sensors. Using their positional
    offset the location of the stylus is determined by triangulation.
    These expensive devices have high accuracy and low artifact noise
    (figure supplied by Pixsys, Inc.).

    1.4 Flashpoint Model 3000i ($14,900)
    Pixsys, Inc.
    5680-B Central Avenue
    Boulder, CO 80301
    tel (303) 447-0248
    fax (303) 447-3905

    A device like this or the much more expensive Optotrak (section
    1.4) is likely to be optimal for many morphometric studies. These
    devices do not have the echo or humidity artefacts of acoustic
    digitizers or the artefacts due to changing magnetic fields
    common with electromagnetic digitizers. These devices are,
    technologically, the newest, thus their high cost.

    Both devices consist of one or more LEDs (Light Emitting Diodes)
    or fiber optic light emitters. These light sources are detected
    by an array of 3 light sensors mounted in a bracket so that they
    are fixed in a non-collinear position. This fixed offset is used
    to triangulate the position of the light source. The light source
    can be attached to a stylus. Data can be collected in point or
    continuous mode. There are device drivers for all the common CAD

    The rated accuracy of the current model is 0.5 mm. Over the next
    few years I expect to see rapid increases in the accuracy of this
    device coinciding with price reductions. The entire device
    weights 22.4 pounds and should be quite portable.

    1.5 Optotrak ($57,500)
    Northern Digital, Inc.
    403 Albert Street
    Waterloo, ON N2L 3V2, Canada
    tel (800) 265-2741/(519) 884-5142
    fax (519) 884-5142

    This device has basically similar components and works in the
    same fashion as the Pixsys. Its accuracy is rated at 0.1 mm in
    the x-y plane, 0.15 mm in z, when the stylus is within 2.25m of
    the sensors. Weighing approximately 90 pounds, not including a
    computer to record and visualize data, it is not easily

    Acoustic Stylus-based Digitizer
    1.6 GP-12 ES ($3200)
    Science Accessories Corporation
    2 Research Drive, P.O. Box 825
    Shelton, CT 06484
    tel (203) 925-1661
    fax (203) 929-9636

    The stylus in this device produces a clicking sound. This sound
    is differentially detected by three wall-mounted acoustic
    sensors. With the three separate readings of the click, the
    location of the source can be triangulated. The stylus should be
    at least as flexible as that of the 3DRAW or DigiTracker (I have
    not tried to use it), making complex concavities more reachable
    by this probe than, for example, those used in fixed-base, servo-
    mechanism digitizing arms (see next section). However this
    maneuverability is not without problems. Convexities may,
    however, prevent sound from reaching the acoustic sensors without
    distortion. High humidity is also known to effect the quality of
    the data. The manufacturer's customer's claim an accuracy of
    0.01", 0.254 mm., in a cubic meter digitizing envelope. There is
    a real-time driver that works with a large number of CAD programs
    including: AutoCAD, Cadkey, Mastercam. Scientific Accessories is
    also willing to develop a customized interface.

    Rigid and Servo-mechanism Arms
    1.7 Cyclone ($52,000)
    Renishaw, Inc.
    623 Cooper Court
    Schaumburg, IL 60173
    tel (708) 843-3666
    fax (708) 843-1744

    This device comes right out of the rapid prototyping industry. It
    includes a computer terminal and digitizing base. This unjointed
    arm digitizer sits in place, retreating in the Z direction as
    protrusions on the object are passed under its probe on a
    linearly moving platform. Successive cross sections are collected
    in this manner to build up an isosurface of the object. It moves
    slowly and gently enough during its slow traverse that there
    should be little chance for damage of specimens (stiff casts
    would be at less risk than friable originals). However, complex
    convexities are ignored. A similar device, the Retroscan
    ($20,000) uses a drill bit to mill a model of a digitized object
    from solid plastic blocks.

    1.8 Diagraph 202 ($1472)
    Seritex Inc.
    450 Barell Avenue
    Carlstadt, NJ 07072
    tel (201) 939-4606
    fax (201) 939-3468

    The Diagraph, designed by Swiss manufacturer GPM, is used to
    directly digitize objects (e.g., a bone) held rigidly in place.
    One end of its rigid arm points at surface features while the
    opposite end of the arm puts a pen on paper. The paper sits on a
    horizontal plane of tracing (or graph) paper set at a particular
    z-height. The Diagraph is useful for the collection of serial
    sections for 3D reconstruction.

    1.9 Faro Arm ($14,400)
    125 Technology Park
    Lake Mary, FL 32746
    tel (800) 736-6063/(407) 333-9911
    fax (407) 333-4181

    Morphometricians have attempted to use digitizing arms for at
    least the past 30 years. It has not been a successful in most
    craniofacial applications because the objects of study have been
    too topologically complex. Both of these devices have four
    joints, giving them a great deal of flexibility. Even so it might
    be difficult capturing some points in the orbits, temporal fossa,
    posterior choanae, the palette and parts of the basicranium.
    Tracing lines on bony tori or elsewhere on the skull is likely to
    range between difficult and impossible. The accuracy of the
    Bronze Series 6 is 0.012 inches, 0.3 mm, within a 6 foot
    spherical diameter.

    Faro manufactures a more expensive line of digitizing arms, the
    Surgicom series. These are used in human surgical planning,
    execution, and follow-up. A complete neurosurgical package,
    including visualization software, has recently been approved for
    use by the FDA is marketed by ISG Technologies (6509 Airport
    Road, Mississauga, ON L4V 1S7, Canada, tel. 905/672-2100, fax.
    905/672-2307). The digitizing arm is primarily used as a virtual-
    reality tool in designing a surgical plan, digitizing landmarks
    to set up a reference frame on the patient that matches that in
    the surgical plan, and as a position tracker for surgical
    instruments. Advances in the use of this and other technologies
    for frameless stereotactic surgery (Zinreich et al., 1993;
    Sandeman et al., 1992) will likely be furthered by the
    incorporation of newer morphometric techniques.

    Figure 3. Romer Model 2000: This highly portable device provides
    high accuracy well within the range required for dental studies.
    Because of their limited mobility, digitizing arms may not be
    useful for complex surfaces. The hard-shell airline check-in case
    on the right holds a portable computer, printer, and the
    digitizing arm.

    1.10 Romer Model 2000 ($105,000)
    Romer Supratech, Inc.
    5145 Avenida Encinas
    Carlsbad, CA 92008
    tel (619) 438-7802
    fax (619) 431-7940

    This model is the smallest of a line of 4 arms with digitizing
    envelopes of between 6.5' and 9.8' in diameter. These arms have
    rotary joints making them more maneuverable than the Faro arm.
    These devices are also designed to be portable. The Model 2000
    weighs 17 pounds. The small base includes a table clamp and an
    i/o processing unit with a serial port. It can thus be easily
    adapted to use with a portable computer. The accuracy rating is
    0.00125" RMS or 0.032 mm as tested by the NIST (National
    Institute of Standards and Technology).

    Data Capture Devices II: Remote Digitization
    In this section we will not discuss multisurface, slice-based
    approaches such as CT or MR-scanning. The two types of digitizers
    discussed here, laser light and optical, are primarily used to
    digitize one surface, the external surface. Optical systems
    calibrate the X and Y values from the power of magnifcation and
    the Z can be determined by the focus level.

    Laser light digitization has a reasonable possibility of
    providing data that can be used to construct highly accurate
    surface representations of the original object, i.e., an
    isosurface. Point resolution is a function of the width of the
    light source beam. Scan accuracy is determined not only by beam
    width, but also camera sensitivity, surface shininess, and the
    system's ability to screen out artefactual reflections. In most
    cases users will benefit from importing the data into a
    visualization package and digitizing the required 3D landmarks
    and/or lines there.

    Multiple Point Source Laser Light Scanning

    2.1 Digibot II ($49,000)
    2800 Longhorn Boulevard, Suite 102
    Austin, TX 78758
    tel (512) 832-6544
    fax (512) 832-1163

    The Digibot II uses a four-axis laser light scanner which checks
    sequential points on the surface. This allows some correction for
    artifacts. The four axis array also obviates focusing problems
    that other systems may have.

    2.2 Hirez Model 3030 ($46,400)
    Cyberware Laboratory, Inc.
    2110 Del Monte Avenue
    Monteray, CA 93940
    tel (408) 675-1440
    fax (408) 675-1494

    This device consists of a moving source of laser light that is
    detected by a video camera at a known angle of offset. Like all
    of this first group of laser light digitizers, the Cyberware
    scanners use multiple laser light sources. This allows the device
    to cover more surface area in less time. An entire human face can
    be scanned in less than 10 seconds. This is regularly done for a
    number of different morphometric applications (Cutting et al.,
    1988; Wohlers, 1992). However, because of the diffuse light
    source artifacts, especially of complex surfaces, tend to corrupt
    the data. The recommendation of scanning a surface from different
    orientations and co-registering the scans can lead to compounded
    artifacts. Assuming no artifacts, landmark accuracy is
    approximately 0.02 inches, 0.5 mm.

    One version of this device also captures color information from
    the surface which can be used to render a more realistic
    isosurface. One version of this device weighs less than 50

    2.3 Hyscan ($n.a.)
    Hymarc Ltd. (Ottawa, Canada)
    G.A. Davis Associates, Inc.
    P.O. Box 36240
    19959 Vernier Avenue, Suite 2B
    Harper Woods, MI 48225
    tel (313) 886-4101
    fax (313) 886-1107

    A multiple point laser device with very high accuracy, +/-
    0.001", and relatively slow data acquisition on large objects.
    The Hyscan accumulates data at the rate of 10,000 points per

    2.4 Optica ($50,000)
    3D Technology, Inc.
    12 Cambridge Drive
    Trumbull, CT 06611-4764
    tel (203) 371-8500
    fax (203) 371-6300

    Using a technology developed in England, but reminiscent of the
    Cyberware scanner, this vendor claims 0.0008", 0.02mm accuracy
    (Vinarub and Kapoor, 1992).

    2.5 Rapid Profile Sensor ($40,000)
    Laser Design, Inc.
    9401 James Avenue South, Suite 162
    Minneapolis, MN 55431
    tel (612) 884-9648
    fax (612) 884-9653

    This device is scheduled to be available shortly. The developers
    of this device claim digitizing speeds comparable with the
    Cyberware scanner with greatly improved accuracy. A whole body
    version of this scanner is scheduled to ship at $145,000.
    Single Point Source Laser Light Scanning

    2.6 CyberScan ($30,000)
    CyberOptics Corp.
    2505 Kennedy Street NE
    Minneapolis, MN 55413
    tel (612) 331-5702
    fax (612) 331-3826

    Sharnoa Corp.
    45901 5 Mile Road
    Plymouth, MI 48170
    tel (313) 925-1661
    fax (313) 454-7198

    This single source laser sits at a pre-set "stand-off" distance
    from the surface to be digitized. It has a high accuracy, 0.001"
    (0.0254 mm.), but can fail on surfaces with convexities that
    block the path of the scan head. These devices would take several
    hours to scan an entire human face. Sharnoa uses the same scan
    head and provides integration with CNC machine milling tools for
    rapid prototyping.

    2.7 Laser Triangulation Probe LTP 60 ($28,700 scan head, $200,000 complete devic
    Carl Zeiss, Inc.
    One Zeiss Drive
    Thomwood, NY 10594
    tel (914) 747-1800/681-7849
    fax (914) 681-7454

    Perhaps the most accurate digitizing head on the market, the
    accuracy of this device is rated at 2.0 microns, 0.0008". The
    probe collects 100 coordinates per second when positioned 115 mm
    away from the object of interest. An observation beam tracks the
    surface to maintain this standoff distance. The device is
    supplied with a visualization environment, Holos-UX, which allows
    the user to define and locate coordinates of landmarks and
    surface patches on the digitized object.

    2.8 Lasar and TriCam ($50,000 and $11,000, respectively)
    Perceptron, Inc.
    23855 Research Drive
    Farmington Hills, MI 48335
    tel (810) 478-7710
    fax (810) 478-7059

    Single laser point devices that use radar focusing. The
    digitizing envelope of the Lasar is commonly a cube of 2-3 meters
    with an accuracy of 0.1 mm. The TriCam is more accurate in its
    smaller digitizing envelope. The TriCam weighs a portable 20

    2.9 MessTechnik OMS 400/250 ($40,000 scan head, $193,000 complete device)
    Wegu Inc.
    Building II
    Orchard Ridge Corporate Park
    Fields Lane
    Brewster, NY 10509
    tel (914) 277-5753
    fax (914) 277-5830

    A close second to the Zeiss device, the accuracy of this device
    is rated to 2.2 microns, 0.000098". The rate of data capture is
    5000 points per second. The full device uses a video source and
    tactile probe to insure it is following the surface carefully.
    The standoff distance from the object is a function of lens
    magnification, from 15 to 75 mm.

    2.10 OP5 ($30,000)
    Renishaw, Inc.
    623 Cooper Court
    Schaumburg, IL 60173
    tel (708) 843-3666
    fax (708) 843-1744

    This laser scanning probe has a rated accuracy of 0.0001". The
    probe rotates about a single axis up to 120 degrees, but must be
    within 14mm of the scanned surface. It collects 200 points per

    2.11 Surveyor ($70,000)
    Laser Design, Inc.
    9401 James Avenue South, Suite 162
    Minneapolis, MN 55431
    tel (612) 884-9648
    fax (612) 884-9653

    The developers of this device claim digitizing speeds comparable
    with the Cyberware scanner and accuracy improvements of at least
    a magnitude, i.e., 0.05 mm. This device would be optimal for
    studies requiring "dental" precision levels and rapid data

    2.12 CadEyes ($80,000)
    Medar Company
    38700 Grand River
    Farmington Hills, MI 48335
    tel (810) 477-3900
    fax (810) 477-8897

    As with all moire photography, light is passed through a screen
    grating. The resulting topographic pattern can be used for 3D
    digitization. Medar claims 0.0001", 0.00254 mm, accuracy in the Z
    dimension with this device.

    2.13 Mini-Moire ($39,000)
    Electro-Optical Information Systems
    528 Euclid Street
    Santa Monica, CA 90402
    tel (310) 451-8566
    fax (310) 393-2453

    Electro-Optical Information Systems device works on the same
    principle as the CadEyes scanner. It claims about the same
    accuracy level, however it is much more portable.

    Convergent Photogrammetry

    2.14 Photomodeler ($895)
    Eos Systems, Inc.
    2040 West 12th Avenue
    Vancouver, BC V6J 2G2 CANADA
    tel (604) 732-6658
    fax (604) 732-4716

    This software uses standard photographs or 35mm slides to produce
    a precise 3D model (AutoCAD 3D *.DXF file) of any object. The
    documentation shows you how to calibrate your camera s focal
    length, image aspect ratio, image position, and lens distortion
    for this application. There are a few more planning few steps to
    take so that all views will be complementary.

    Macroscopic Stereomicroscopes
    2.15 Reflex Microscope ($35,000)
    Reflex Measurements Limited
    Hadley House
    Water Lane
    Butleigh, Somerset BA6 8SP, England
    tel/fax (44-458) 50332

    This device has been used with great success on small biological
    specimens (MacLarnon, 1989). An accuracy of 0.002 mm is claimed
    for the 110 x 110 x 50 mm digitizing envelope.

    2.16 Tool-Makers and Digital Contracers Microscopes ($35-45,000)
    M-R-O Industrial Supplies, Inc.
    440 South Main Street
    Manville, NJ 08835
    tel (201) 368-0525/(800) 345-4135
    fax (908) 707-1266

    The Tool-Makers device has a 100 x 100 x 50 mm digitizing
    envelope with a claimed accuracy of .02 mm. The Digital
    Contracers Microscope has a 100 x 100 x 25 mm digitizing envelope
    with a claimed accuracy of .02 mm. These are standard optical
    digitizing devices designed for the tool and die industry but
    also readily adaptable to sub-macroscopic morphometrics,
    especially on micro-organisms and teeth.

    2.17 Video Comparator DVC110 ($8900)
    3900 West Segerstrom Avenue
    Santa Ana, CA 92704
    tel (714) 545-0401
    fax (714) 641-0946

    More like the Reflex in having a potentially larger digitizing
    envelope: 2 x 2 x 4 . The manufacturer rates its accuracy at
    0.0002 , 0.05 mm; a level of accuracy acceptable for mammalian
    dental studies.

    III Visualization Software

    NATO conference attendees tested the shareware visualization
    environment created by Dennis Slice (this volume) DSDigit that
    runs under MS-DOS. It provides a view of a data "cube" from
    various sides and can be used to calculate distances between
    landmarks. Jeffrey Walker (SUNY-Stony Brook) demonstrated his
    Morphosys package for the Mac. It provides sophisticated
    morphometric image analysis tools.

    The visualization environments discussed below have been
    developed for different primary audiences but all have some
    application useful to morphometrics. Many of these packages offer
    a 3D "pick" tool to collect landmark and line tracing coordinates
    from isosurface models. Many of these packages provide image
    enhancement tools such as isosurface shading and lighting options
    to help the user better identify the morphology to be digitized.


    3.1 Khoros 2.0 (shareware)
    (Multiple UNIX platforms, NeXT, PC-XWindows, Macintosh-XWindows)
    Usenet: comp.soft-sys.khoros.
    FTP: Khoros may be downloaded from the following FTP Locations
    (read $KHOROS_FTP/release/install.ftp first):
    USA /pub/khoros
    USA /pub/window-sys/khoros
    CANADA /pub/khoros
    GERMANY ftp.rrz.Uni-Koeln.DE /graph/khoros
    GERMANY /local/khoros
    ITALY /pub/khoros
    JAPAN /pub/khoros
    UK /pub/cgu/khoros
    UK /pub/uunet/window-sys/khoros

    A powerful visualization environment written at the University of
    New Mexico. There are several tools for adjusting isosurface
    thresholds using image gradient information.

    3.2 NIH Image 1.54 (shareware)
    ftp site:
    Source Site:
    Source Path: \pub\image
    Source Name: nih-image-154-fpu.hqx

    A plug-in (Plug-in Digitizer), written by Cyrus Daboo of
    Cambridge University, now allows NIH Image to grab images using
    the frame grabber built into the AV Macs or from any other
    Quicktime compatible digitizer with a 'vdig' component. NIH image
    has tools for measuring areas, distances and angles, and for
    counting things. The digitizer patch is available as a binhexed,
    self-extracting archive by anonymous FTP from,
    in the /pub/nih-image/plug-ins directory. The archive also
    includes a report on the AV digitizer that points out some its
    flaws, such as automatic gain control that can't be disabled. It
    also includes Apple's AV Digitizer Options extension that allows
    the user to switch the AV digitizer into grayscale mode, which
    greatly improves the quality of images captured using grayscale

    3.3 QSH (shareware)
    (multiple Unix workstations)
    Dr. Marilyn Noz
    Department of Radiology
    New York University School of Medicine
    550 First Avenue
    New York, NY 10016-6402

    Radiological image handling software with a wide range of
    previsualization tools, including: pixel editing, thresholding,
    and in-slice measurements. After the object of interest has been
    isolated, a simple image stack (*.qsh file) and header file
    (*.qhd file) can be built.

    3.4 SGI Explorer (gratis software with standard workstation purchase)
    Silicon Graphics Incorporated
    2011 North Shoreline Boulevard
    Mountain View, CA 94039
    tel (415) 390-1960/(800) 800-4744
    fax (415) 390-6153

    Free visualization tool that comes with an SGI workstation.
    Piggybacking on the power of SGI's GL (Graphics Language), it
    provides several tools to display and explore 3D data.

    3.5 Viewit (freeware)
    (Multiple UNIX platforms, Macintosh)
    National Center for Supercomputing Applications
    Computing Applications Building
    605 E. Springfield Avenue
    Champaign, IL 61820

    Viewit has a minimal user interface. It can be used to produce
    volumetric images from slice data. It is known to require a lot
    of RAM. There are also visualization tools. The Viewit electronic
    newsletter is available from Clint Potter
    is the primary author and contact at:

    Commercial Packages

    3.6 Alice ($1495, $1046.50 academic price)
    (Windows, Windows NT, Macintosh, PowerPC)
    Hayden Image Processing Group
    1919 14th Street, Suite 405
    Boulder, CO 80302
    tel (303) 449-3433
    fax (303) 449-3772

    Originally released under the nomen: DIPStation. A
    medical imaging toolkit with help for segmentation,
    volumetric image rendering, measurements from slices
    and volumes, and data analysis. The segmentation
    tools in Alice are stronger than many more expensive

    3.7 Analyze 6.2 ($16000)
    (Multiple UNIX platforms, Macintosh)
    Mayo Medical Ventures
    200 First St. SW
    Rochester, MN 55905
    tel (507) 284-8452
    fax (507) 284-5410

    Analyze offers a large set of slice data processing tools and 3D
    image-building algorithms (Robb and Hanson, 1991). Analyze
    provides import/export facility for a large number of
    radiological, medical imaging, and histological data formats.
    Linear measurements, landmarks, and line tracings may be captured
    from the resulting isosurface models.

    3.8 AVS ($6500)
    (Multiple Unix platforms, Macintosh, Windows NT, Windows)
    Advanced Visual Systems, Inc.
    300 Fifth Avenue
    Waltham, MA 02154
    tel (617) 890-4300
    fax (617) 890-8287

    This visualization environment comes with a large number of
    image-handling primitives that assist in 2D and 3D image
    analysis. These primitives support several hardware-based
    graphics languages such as SGI GL, Xlib, GDI, XGL, and PEX,
    speeding redraw of the user s private interface.

    3.9 Data Explorer ($5900)
    (Multiple UNIX platforms)
    IBM Data Explorer Group
    Product Marketing, Department 590
    8 Skyline Drive
    Hawthorne, NY 10532
    tel (914) 784-5089
    fax (914) 784-5082

    Image manipulation software with applications similar to
    3DViewnix. Isosurface building algorithm Alligator (Kalvin, 1991)
    which derives its flexibility from the "Winged Edge" data
    structure (Kalvin et al., 1991). Recently powerful data reduction
    software, "Superfaces", was added to this package. The package
    also includes powerful data capture pick tool and image handling
    primitives (Rogowitz and Treinish, 1993). These image handling
    primitives greatly speed the creation of tools for image

    3.10 IDL ($3750, $1500 to educational institutions)
    (Windows, Macintosh, Multiple UNIX platforms)
    Research Systems Inc.
    2995 Wilderness Place, Suite 203
    Boulder, CO 80301
    tel 303-786-9900
    fax 303-786-9909

    Interactive Data Language provides tools for image data
    reduction, visualization, segmentation, measurement collection,
    and analysis. Instead of canned image processing tools, there is
    a high level, user-friendly, image processing language, IDL.

    3.11 Image Volumes ($4500)
    Minnesota Datametrics Corp.
    1000 Ingerson Road
    St. Paul, MN 55126-8146
    tel (612) 482-7938
    fax (612) 490-9717

    A package to assist collection of measurements from volumetric
    images which includes large image processing toolkit. Provides
    facile collection of linear distances, surface areas, and
    volumes. Also includes native tools for superimposition by
    landmarks, bounding boxes, or other transformations.

    3.12 MacStereology ($750)
    Ranfurly Microsystems
    16 Derwent Avenue
    Haddington, Oxford OX3 0AP England
    FTP demo copy:

    This program includes tools to make measurements directly from
    images or to produce 3-D reconstructions from stacks of images.
    MacStereology can also accept data from digitizing tablets or
    *.PICT files. The user can set magnification. Measurement tools
    include area, perimeter and center of gravity. Requires only 1
    megabyte of RAM.

    3.13 Mocha ($1495)
    Jandel Scientific
    2591 Kerner Boulevard
    San Rafael, CA 94901
    tel (800) 874-1888/(415) 453-6700
    fax (415) 453-7769

    Primarily aimed at a histological and microbiological audience,
    this package provides a large number of general image processing
    and data capture tools. Analysis proceeds primarily on x-y slices
    of 3D subjects, but 3D reports can be generated.

    3.14 Surfacer 3.1 ($4000)
    (Multiple UNIX platforms, Windows)
    Imageware, Inc.
    313 North First Street
    Ann Arbor, MI 48103
    tel (313) 994-7300
    fax (313) 994-7303

    Surfacer imports data from a wide variety of standard formats. In
    addition to data rendering and digitization it offers a large
    complement of CAD reverse engineering tools.

    3.15 3DViewnix ($1000)
    (Multiple UNIX platforms)
    Medical Imaging Processing Group
    Radiology Associates
    University of Pennsylvania
    Brockley Hall, 4th Floor
    428 Service Drive
    Philadelphia, PA 19104
    tel (215) 662-6780
    fax (215) 898-9145

    A large number of image manipulation and data capture tools
    (Udupa et al., 1993), primarily for radiological slice data
    (e.g., MR and CT) but adaptable to other 3D data sets.
    Isosurfaces are built from topological information encoded by a
    highly adaptable data structure known as the Shell (Udupa and
    Odhner, 1993).

    3.16 VoxBlast ($2500)
    (Multiple UNIX platforms, Macintosh, PowerMac, Windows)
    VayTek, Inc.
    P.O. Box 732
    305 West Lowe
    Fairfield, IA 52556
    tel (515) 472-2227
    fax (515) 472-8131

    VoxBlast produces isosurfaces from a wide variety of slice data.
    There are tools to take measurements from these isosurfaces and
    to calculate volumes.

    3.17 VoxelView ($10,000, academic price $5000, $1295 Macintosh version )
    (Irix and Macintosh)
    Vital Images
    505 N. Fourth St., Fairfield, Iowa 52556
    tel (515) 472-7726
    fax (515) 472-1661

    Produces 3D isosurface models from a variety of data sources. One
    of the few visualization environments (other than SGI Explorer)
    that takes advantage of SGI"s IRIX GL (Graphics Language) and
    thus the hardwired graphics engines found in SGI workstations.
    This native hardware support speeds up image rendering. Reduced
    redraw times mean faster digitization from multiple views as well
    as if you are changing visualization parameters (e.g. threshold,
    contrast, number of light sources, etc.).

    IV Rapid Prototyping Devices
    Generating an average landmark configuration, especially if the
    landmark density is high enough to warrant an isosurface model,
    is a major part of the New Morphometrics. Similarly the form of
    an average form or morphotype is best viewed as a real model.
    These three dimensional printers are still very expensive but
    have dropped enough in price to make requests for single copy
    output affordable. This copy can then be used as a positive in
    mold production if copies are needed.

    4.1 FDM 1000 ($50,000)
    Stratasys, Inc.
    14950 Martin Drive
    Eden Prairie, MN 55344
    tel (612) 937-3000
    fax (612) 937-0070

    You select a Z axis within your 3D data set. The data are then
    divided into Z slices of 0.050" thickness. An extruder begins at
    the center of each Z slice and spins concentric circles emitting
    a 0.050 thick filament of plastic at just over the melting
    temperature. The plastic left wherever there was data in the
    original data set instantly cools. The extruder finishes that Z
    slide and bumps up 0.050" to the next Z slice. If an overhang is
    expected in the data a bridge is built that can be removed later.
    The models produces are almost seamless. It can interface with
    most of the aforementioned data visualization environments.

    4.2 Helisys ($95,000)
    Helisys, Inc.
    Building M10
    2750 Oregon Court
    Torrance, CA 90503
    tel (310) 782-1949
    fax (310) 782-8280

    The volumetric data is converted to Z slices along the preferred
    Z axis. Each slice is cut into a sheet of paper. The sheets of
    paper are then laminated together. The models have hard-wood
    resilience and are virtually seamless. Unlike laser sintering
    devices there is no warping in the plastic model already produced
    due to heat in the part that is being formed. It can interface
    with most of the aforementioned data visualization environments.

    4.3 QuickCast ($195,000)
    3D Systems
    26081 Avenue Hall
    Valencia, CA 91355
    tel (805) 295-5600
    fax (805) 257-1200

    A standard sterolithographic device (Jacobs, 1993) which uses a
    laser to etch the desired surfaces in an epoxy resin block. This
    technique is referred to as laser sintering. Built in a series of
    Z slices, slice thickness can be as low as 0.005". It can
    interface with most of the aforementioned data visualization

    4.4 SLS Sinterstation ($350,000)
    DTM Corp.
    1611 Headway Circle, Building 2
    Austin, TX 78754
    tel (512) 339-2922
    fax (512) 339-0634

    This is a standard laser sintering device. DTM claims to have
    made more careful study of the materials used by other laser
    sintering vendors, especially for biomedical applications. It has
    been used to produce skeletal casts. It can interface with most
    of the aforementioned data visualization environments.

    4.5 Solider ($490,000)
    Cubital America Inc.
    1307F Allen Drive
    Troy, MI 48083
    tel (810) 585-7880
    fax (810) 585-7884

    A standard stereolithography device developed in Israel. It can
    interface with most of the aforementioned data visualization

    4.6 Z-mode ($800 per model + model costs)
    3D Medical Imaging Services
    1241 Garden Street
    San Luis Obispo, CA 93401
    tel (805) 542-9281
    fax (805) 542-9168

    Using proprietary volumetric rendering software and the Cubital
    3D printing technology from ISG (see Metrecom Arm description
    above). This company accepts a wide range of 3D CT and MR data
    for the production of 3D models. These models are typically used
    in surgical planning or prosthesis development. The Z plane
    resolution of these models is claimed to be 0.002".


    Most morphometric activities discussed at the NATO conference
    derived their data from the external surfaces of organisms, the
    leading 3D data capture technologies are laser light based.
    Laser-based digitizers are currently the most expensive devices,
    therefore advances in less expensive electromagnetic devices such
    as the Polhemus 3DRAW may be the near term answer for landmark
    and space curve digitization. The Laser Designs device looks to
    be a breakthrough in combining speed and accuracy in a single
    point source laser light digitizer. Three dimensional
    visualization software is now readily available from a variety
    sources. High quality three dimensional printers should start
    making their way into the mainstream shortly.

    Acknowledgment: Thanks to Leslie Marcus and Marco Corti for their
    kind invitation to present this paper at the NATO ASI Workshop.
    Thanks to Jim Rohlf, Alan Kalvin (IBM TJ Watson), Chip Maguire
    (Columbia Univ.), and John Russ (Univ. North Carolina) for
    careful comments on the manuscript. Much of the visualization
    information was obtained from "med.volviz.faq.94-08.2/3" and
    "med-volviz-faq-94-10" produced by Matti Haveri (

    Literature Cited

    Bookstein, FL (1991) Morphometric Tools for Landmark Data:
    Geometry and Biology. Cambridge: Cambridge University Press.
    Coatrieux JL, Barillot C. A survey of 3D display techniques to
    render medical data. In: Hohne KH, Fuchs H, Pizer SM, eds.
    3D imaging in medicine. Berlin: Springer-Verlag, 1990; 175-
    195.)Corner BD, Lele S, and Richtsmeier JT (1992)
    Measurement error of three-dimensional landmark data. Quant.
    Anthropol. 3:347-359.
    Corner B and Richtsmeier JT (1992) Cranial growth in the Squirrel
    monkey (Saimuri sciureus): A quantitative analysis using
    three dimensional coordinate data. Am. J. Phys. Anthropol.
    Corti et al. this volume??
    Cutting CB, McCarthy JG, and Karron DB (1988) Three-dimensional
    input of body surface data using a laser light scanner.
    Annals of Plastic Surgery 21:38-45.
    Fruhauf M (1991) Volume visualization on workstations: image
    quality and efficiency of different techniques. Comput. &
    Graphics 15:101-107.
    Jacobs, P (1993) Stereolithography: From art to part. Cutting
    Tool Engineering 45:1-3.
    Kalvin AD (1991) Segmentation and surface-based modeling of
    objects in three-dimensional biomedical images. Ph.D.
    thesis:New York University.
    Kalvin AD, Cutting CB, Haddad B, and Noz M (1991) Constructing
    topologically connected surfaces for the comprehensive
    analysis of 3D medical structures. SPIE 1445:247-258.
    Kalvin AD, Dean D, Hublin J-J, and Braun M (1992) Visualization
    in Anthropology: Reconstruction of Human Fossils from
    Multiple Pieces. In (AE Kaufman and GM Nielson, eds.):
    Proceedings of IEEE Visualization '92, pp. 404-410.
    Krieg JC, Jones HR, Rodgers AG, and Schneider MR (1992) A 4
    millisecond, low latency, 120 Hz, electromagnetic tracker
    for virtual reality applications. Internal Application Note,
    Lele S and Richtsmeier JT (1992) On comparing biological shapes:
    Detection of influential landmarks. Am. J. Phys. Anthropol.
    MacLarnon AM (1989) Applications of the Reflex instruments in
    quantitative morphology. Folia Primatol. 53:33-49.
    Magnusson M, Lenz R, and Danielsson PE (1991) Evaluation of
    methods for shaded surface display of CT volumes. Comput.
    Med. Imaging Graph. 15:247-256.
    Raab FH, Blod EB, Steiner TO, and Jones HR (1979) Magnetic
    position and orientation tracking system. IEEE Trans.
    Aerospace and Elec. Sys. 15:709-718.
    Richtsmeier JT and Walker A (1993) A morphometric study of facial
    growth. In (A Walker and R Leakey, eds.): The Nariokotome
    Homo erectus skeleton. Cambridge: Harvard University Press,
    pp. 391-410.
    Robb AR and Hanson DP (1991) A software system for interactive
    and quantitative visualization of multidimensional
    biomedical images. Austral. Phys. and Eng. Sci. in Med.
    Rogowitz BE and Treinish LA (1993) An architecture for rule-based
    visualization. IEEE Visualization 93:236-234.
    Sandeman DR, Patel N, Chandler C, Nelson RJ, Coakham HB, and
    Griffith HB (1992) Advances in image directed neurosurgery:
    Preliminary experience with the ISG Viewing Wand compared
    with the Leksell G frame. Clin. MRI 2:91-92.
    Udupa JK and Odhner D (1993) Shell rendering. IEEE Comp. Graphics
    and Applic. 27:58-67.
    Udupa JK, Goncalves KI, Narendula D, Odhner D, Samarasekera S,
    and Sharma S (1993) 3DVIEWNIX: An open, transportable
    software system for the visualization and analysis of
    multidimensional, multimodality, multiparametric images.
    SPIE 1897:47-58.
    Vannier MW and Conroy GC (1989) Imaging workstations for
    computer-aided primatology: Promises and pitfalls. Folia
    Primatol. 53:7-21.
    Vinarub EI and Kapoor N (1992) 3D digitizing hidden surface using
    borescopic sensor technology. Proc. App. Machine Vision
    Conf. 92: MS92 160:1-11.
    Wohlers TT (1992) 3D Digitizers. Computer Graphics World 2:73-77.
    Zinreich JS, Tebo SA, Long DM, Brem H, Mattox DE, Loury ME,
    Vander Kolk CA, Koch WM, Kennedy DW, and Bryan RN (1993)
    Frameless stereotaxic integration of CT imaging data:
    Accuracy and initial applications. Radiology 188:735-742.