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years of traditional optical tooling practice. Safety, which
is of high social and economic importance, has also been
improved. In one and a half years of implementation
there has yet to be an on the job injury. And finally the
integration of Data Management software (SAS) with the
final coordinate outputs of measurements from the shop
floor will enabled the shipyard to utilize data for SPC
analysis that in the past has been neglected due to the
high costs of manual input. This is a very economical
effort because the data output is a standard ascii
delimited text file it is easily imported and shared
between softwares. It is very satisfying to see mea-
surement data be used for multiple purposes. Not only is
data used for production service; but for process control
and capability determination then monitoring as in-
dicators of quality levels in the quest for continuous
improvement.
2. VISION METROLOGY AND CAD
2.1 Structural Design
Traditional uses of CAD in shipbuilding is typically
focused on extracting data in .dxf format from design
plate and/or shape files to create drawings for
visualization and dimensioning purposes.. Once these
drawings are created and distributed to the various
shipyard manufacturing areas they are used for many
purposes from planning through ship's completion and
delivery. During a ship's life cycle many construction
measurements are taken and constantly being compared
to paper copies of these design drawings manually ...
one at a time. However; for BIW personnel, much more is
being done. Due to the versatility of the digital
measurement software in its handling of data outputs as
delimited ascii text, CAD software (AUTOCAD, etc..)
being used extensively as a graphical interface to import
actual measurements directly into a drawing. Customized
programming routines easily orient, layer, and even color
code points in seconds that are routinely shared across
networking platforms. There is an unprecedented link
evolving between the many shipyard disciplines.
Increased three dimensional mea-surement capabilities
has resulted in Structural Design, Accuracy Control, and
Manufacturing, areas requesting more Surveyor mea-
surements be performed and analyzed.
2.2 Measurement Enhancement
In addition to improving the interpretation and
visualization of actual ships data CAD is used more and
more to enhance the measurement process itself. The
benefits are realized in planning stages where these very
same design drawings are used by the Surveyors for
initial target placement. Customized programs enable the
operator to affix alpha-numeric tags appropriately
sequenced and located for the extraction of XYZ
coordinates. serving three basic purposes. The first is to
instill a systematic approach to labeling and targeting
each application. The ensuing consistency minimizes
wasted time and effort. Secondly the extracted design
data can be imported into the measurement software to
increase automation of image measurement. By knowing
the approximate coordinates of each target the software
265
can automatically drive to each point prior to bundle
adjustment calculations. This reduces time setting up the
initial image measurement and assists in target
recognition in places where obstructions are of concern.
Thirdly the extracted design XYZ coordinates form the
basis for comparisons to the as-built conditions. For
similar products or repetitive in-process checks this forms
the basis for SPC techniques to be developed and
applied for process control and capability monitoring .
2.3 Shop Floor Results
The bottom line to the shop floor mechanic is that they
are receiving three dimensional data in less than half the
time of past measurements. They now have the ability to
view pictures, graphs, and drawings of products as well
as processes. The effectiveness of enhanced visual-
ization techniques and communication of results cannot
be over emphasized. For many three dimensional
measurement systems the job begins with a request for
data and ends with the delivery of a measurement file
from the Surveyor to the shop floor mechanic. Today this
is only a small portion of the process. Measurement
results now are left on-line for access by almost any one.
Depending on ones point of view some would say this
cooperation and growth is a small scale example of
Concurrent Engineering at its finestThe support received
for improved measurement capabilities (upper
managements commitment to implementation of Digital
Photogrammetry) is one of many initiatives at BIW aimed
at supporting and sustaining a truly empowered, high
per-formance work organization.
2.4 Summary
The future promises to be exciting for BIW as this overall
effort becomes refined and focused. More applications
will be found while new equipment and technologies are
developed then brought on-line. For this paper; though,
we will stay with the present and go on to discuss
individual applications depicting the benefits of DCRP in
shipbuilding. Examples of data visualization and analysis
techniques (CAD & SAS) employed within the
measurement process will be provided. The first
application, Unit Erection, will be covered in depth to
build a basic understanding of equipment usage and
benefits. The remaining applications will offered more for
diversity; being representative samples of jobs
throughout the construction process.
3. CURRENT SHIPBUILDING APPLICATIONS
3.1 Unit Erection
With the acceptance of modularized construction in
shipbuilding a common practice is to build interfacing
steel edges with excess material on one end to be
trimmed during the erection process. Initial manufacturing
practices positioned the module in the ship’s plane, at an
approximate location on the ship, and traced the existing
ship’s shape on the erected unit so that when the excess
steel was burned off the unit should fit into its proper
place. Significant gains in productivity were realized by
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B5. Vienna 1996
