th Order
tortions,
se linear
uadratic
e (Hein,
ution of
triangle
ormed.
5 of 2nd
ol points
tribution
shape of
2 4. Topological Relations of Plans
For the flexibility of handling transformation functions for
object partial planes f, it is provided , that a subdivision
along the places or lines of unsteadiness is possible.
From the view-point of topological relation R it is often
necessary to subdivide façades in detailed parts f. This
results in a hierarchical structure G(f), in which a priori a
classification of transformation functions can be handed
down. Between the planes f,, f, anf f, exists the relation
R (strict partial order), if
fq cfo A fo c fa for all 4, fo,fa € F
(r R fo ^ f R fa) > f4 Rf (5)
t Rfa2 f2 f, forallfi,fae F
is given.
3. REALIZATION
3.1Principle of the Procedure
Inthe foreground ofthe system design stands a high user
interaction for experimentel working by the creation of
orthplans. The development of the orthophotosystem
has the following principles:
. Interactive displaying of multi images in an industrial
window environment.
. Using interactive manipulation for the orthophoto
production.
. Interactivetesting oftransformation and resampling.
. Fast mode for creation of orthophotos in low-
resolution.
. Batch-mode for generation of orthophotos in high-
resolution.
. Inputof external 3D-models (i.e. DXF from AutoCad)
into the system.
. Combination: orthophoto with geometric-data.
. Using of all built-in image processing tools after
generating orthophotos.
° Standard image file formats for outputs
(i.o. TIFF, VFF, EPSF).
2. m n ntrol Point Handlin
The object geometry (control) for a digital rectification is
done by analytical stereo-measurements on a Planicomp
P3 combined by a CAD-system (AutoCAD), where a
plane structure is defined by layers. Default attributes
such as types of transformation can be assigned to the
planes. The subarea hierarchy with the topological relation
Ris found out of the CAD-layer structure and transfered
to the orthophoto system.
Conceptively all methods can serve for the geometric
data (measurements at the object, triangulated points
etc.), which are necessary for single image rectification.
Geometrical informations, such as the subdivision of the
fagade struture in limited subareas andthe control points,
are derived from a 3D-object model.
The position of control points and the area limits of any
plane can be transformed back from the 3D-model to the
image plane, if the interior and exterior orientation are
known (Fig. 3.2.1). For control points of images, which
are not contributing to the model, corrections may be
necessary.
The free choice of projection planes garantees the
handling of image mosaics and allows the computation
of control point positions and of the limits of planes,
Puy) = fc Y. 2).
3D-Object-Model (World-Coordinates)
Inverse
Projection
Projection
=
—B>| Image plane 1 Ho
—
©
—»| Image plane 2 |-o—B>| Projection
plane
—Pp»| Image planen — ©°
Rectif
Fig. 3.2.1 3D-Object-Model
3.3. Imagehandling and Multiwindowing
For the working with digital images in an interactively
window based user system a pyramid was constructed
(Fig. 3.3.1). It represents a multiresolution structure of
the originalimage (Ackermann, 1991; Rosenfeld, 1984).
This concept allows to display the hole image of a lower
resolution in an overview-window. In this window it is
possible to select any region by zooming parts in a