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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B4, 2012
XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia
Figure 4. Top view of completed roads
We have developed a data updating method for roads using
as-built drawing CAD data (see the diagram below). The
corresponding part is cut out from the road database of the
spatial data infrastructure and provided to the construction
contractor. The contractor modifies the data with the changes
made by the construction and submits the modified electronic
data. The road database can be updated simply by incorporating
the submitted data into it.
If this can be achieved, road databases can be updated while
maintaining quality.
OGIS data
Cutout and provision of the
construction arez
Belivery of elec-
ironic document
Figure 5. Partial updating cycle of road data
4.2 Partial updating of building data
Changes in building data are occur for three primary reasons:
new construction, loss and alteration. In the event of loss, a
building can simply be deleted from the registration database.
However, accurate shapes and locations are needed to add new
construction and make alterations.
One of the earliest-stage documents indicating these changes is
a written application for building certification. This application
is submitted to the municipality when a building is to be built
in a city planning area. The submission of the application is
required by law. By using the vicinity map and drawing
attached to the application, data on individual buildings can be
updated every time changes are made. These documents,
however, do not have geodetic coordinates. Updating the data
involves three stages: finding a ballpark location from the
address provided on the application; identifying the location of
the building from its relative position to the surrounding roads
and neighbors on the vicinity map; and then drawing the shape
from the dimensions provided on the attached drawing. In order
to update data while maintaining location accuracy, this method
is desirable as it provides such information as distances from
roads and the position on the premises.
In reality, digitization of this data is not required by law, so
29
documents have to be rasterized and digitized. Even a suburban
municipality has several thousand buildings to update each year.
The updating method above is impractical from the standpoint
of working efficiency.
In Japan, most municipalities have a house ledger to assess
fixed assets. The house ledgers often do not show roads or
other planimetric features but only the shapes and attributes of
buildings. House ledgers are updated every year by fixed asset
departments and therefore they provide very up-to-date
information on houses. It would be ideal for the house ledgers
to be integrated with the building database contained in spatial
data infrastructure. But in reality, this is rarely the case because
of the protection of personal data and due to many other
problems.
To avoid these problems, we have developed an updating
method using data of the house ledger excluding the attributes,
i.e., only shapes.
Figure 6. House ledger
When a house ledger is used, unlike the as-built drawing or the
written application for building certification, changes over time
need to be identified. The most efficient way to identify them is
to label each shape with its age and identify changes from their
ages. However, few municipalities include time information for
each shape in the ledger. Furthermore, it is difficult to share
such information because of issues with the protection of
personal data. In our study, we decided to use the shapes in
house ledgers over two years to identify changes over time.
Following is the updating method we have developed.
(1) Identify changes over time using house ledgers for two
years.
(2) Identify the area to update in the old data.
(3) Conduct visual examination.
(4) Update data.
Applying this method provides very up-to-date data that is
better than the data provided with a conventional updating
frequency of once ever several years and is constantly
available.
5. VERIFICATION
5.1 Updating of road data
We conducted a field study on Mie Prefecture to verify the
problems and effects of the updating methods we developed. As
different road management entities are very likely to create
their as-built drawings in different ways, we obtained the data
from the national government, prefecture and municipalities
and verified location accuracy and other quality to see whether
they could be used for updating.
