International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol XXXV, Part B2. Istanbul 2004
3.2 Revision strategy
The TOP10DK concept is based on outsourcing. However, all
planning, certain control procedures and the final database
updates are done in-house. The companies that are to carry out
the photography, the image scanning and the revision process
are selected from separate tenders. Normally, 5 - 10 bids are
received within cach category.
The heavy part is the revision of the geometry. The area in
question per year is approximately 10.000 km? which is
subdivided into 6 — 10 stages. 3 — 4 photogrammetric
companies share the total revision task.
The companies are provided with all necessary material from
KMS including a copy of the existing database and software
developed for the in-house control phase (Kamper, 2004). The
idea behind is, that the data producers can run a number of the
automatic control procedures themselves checking for topology,
network consistency etc.
The revision is based on incremental updates, i.e. only changes
are registered and received at KMS as +/- data. New objects are
measured photogrammetrically and objects that no longer exist
are deleted. Changes in geometry of existing objects are dealt
with in two different ways. Small objects with significant
changes are erased and replaced by a new registration (object
+/- data). For bigger objects, only changes are registered and
added or subtracted from the existing object (incremental +/-
data). (Hoejholt et al., 1999)
All object points have attached registration information about
instrument, image numbers, ground control point numbers etc.
In order to reduce the amount of written material, to avoid
misunderstandings and to speed up the revision process a
couple of Internet services have been introduced. All geodetic
control points, corresponding sketches and co-ordinate lists are
available through an Internet service. This year all ground
control from the original aerotriangulation is also available
through the Internet providing scanned images showing the
positions of tie points from the aerotriangulation. The
corresponding detailed and hand drawn sketches have been
scanned as well and appear in the service together with co-
ordinate lists (Figure 3).
An important revision trend is observed during the last few
years. [t is known as administrative revision where the
information is received as temporary data from partners in the
private or public sectors. An example is information on new or
changed roads where the database is updated 3 times per year
with preliminary information. The information is then
confirmed by the 5 years revision cycle.
It is believed that this kind of information will become more
and more important as the demands on topicality increase. An
update strategy, where the information is received from an
increasing number of partners and subcontractors with an
increasing frequency.
4. COMMON OBJECT TYPES
Traditionally, topographical and large-scale mapping have been
produced separately. This tradition has been inherited as
regards the geo-spatial databases.
However, there is an increasing awareness about the fact that
the some objects are recorded several times simultaneously but
for different purposes or different customers. Important
infrastructure objects are registered several times according to
different specifications and stored in different databases.
Realizing this, the idea was born to define "common object
types" (COT), i.e. object that are found in both topographical
and large-scale databases. A specification for these objects is
being prepared considering both the establishing and the
revision processes. Examples of entities defined as COT are
buildings, transport- and hydrographical networks, coastlines
and administrative units.
In practice, COT are found in both databases while the
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