Superimposition is used for giving a total view of already
measured elements.
The measurement of cylinders and circles is done with
special adjustment modules. Thus it is possible to measu-
re boundary lines (instead of homologous points) for the
calculation of an object (Straub 1996). By using an inte-
grated "merge"-function, it is possible to fit several parts
of the axis of pipes. This is an important feature for the
CAD-construction.
Further functions are for example the determination of
points of intersections or cutting angles.
When recording the plant geometry it is possible to sup-
plement object attributes. These are appended to the
geometric elements also called "tags" and can be imme-
diately used in a plant design system.
A distinct structuring of a plant is done by subdividing the
measured objects in elements that belong together. Up to
63 layers can be defined in the system to arrange these
measurements. This feature is similiar to a common CAD-
system, like Bentley's MicroStation, which is nearly an
"industry"-standard as the basis of plant design systems.
By using these layer techniques the operator is able to
fade in or out the parts of the plant he needs to see. Thus
a general object view is given, independent from the
mass of measured objects.
To transfer 3D-data and attributes into the CAD-system
an intelligent DXF-interface is integrated into PHAUST.
This interface guarantees that the complete available
information is integrated in the CAD system without any
data loss. All elements will retain their characteristics, so
a line will remain a line, a cylinder a cylinder. Further
constructions are not nessecary (Fig. 4).
Figure 4 : General view of objects measured in PHAUST
5. CAD-CONSTRUCTION
After the mass evaluation with the photogrammetric work-
station the aim of the CAD-process is to complete the
photogrammetric model. Manual measurements on the
one hand, and obtaining object information from existing
2D-plans on the other hand are the basis for the contruc-
tion of missing elements.
Generally this concerns the construction of circular lines,
large vessels or other complex objects e.g. pumps. In this
228
context it is sometimes nessecary to generalize the model
to the main structures (edges and knotes). Further Steps
in a possible work-flow are characterized by
assignment of materials
camera drive
object animation
building of virtual realities by VRML
The first aim of photogrammetric as-built documentation
is to get a high quality 3D-object model of a plant. A se-
cond one can be formulated by reducing the part of CAD-
construction up to a maximum of 20-3096 of the whole
project costs. Modelling with PHAUST "plant"-module
meets these requirements (Fig. 5 and 6).
Figure 5 : General view of the plant after CAD-
construction
Figure 6 : Details (after rendering)
Table 2 gives an overview of all process steps and ne-
cessary times.
A useful effect concerning CAD-construction is the inte-
gration of libraries with standard structural parts used in
plant design systems. Those elements might be for ex-
ample gate valves, stopcocks, etc. These structural parts
are used to be inserted via 3D-points (measured in
PHAUST) into the 3D-plant model.
Another possibility is to generate of macro-programs,
which work this job automatically. The overall aim of the-
se modules ¢
costs while ct
At present PI
and further pl
Tab. 2 : Ovel
Methods anc
se-range phe
ve to hand-n
today. With
dustrial plant
metrically ex
The presente
of a plant i
however, to |
the measurir
are hardly ac
Hilgers, G.
Diplomarbeit
published.
Kruth, P. 19
tenmodell &
Kraftwerk sy
Rollei fotote
RolleiMetric
Germany.
Straub, B. 1
Einbeziehun
Hannover, C
Woytowicz,
Sches Ausw
In : Photogi
vermessung
Germany.
