Geospatial technologies integration / management
Database design and implementation
The majority of GIS applications were using proprietary Relational Database Management
Systems (RDBMS) and as we know 70'XOto 80% of the cost when implementing a GIS goes to
collecting cleaning and storing the data. The maintenance of this main asset needs to be through
a technology that can manage different formats of data reliably, and with a low aging ratio to
avoid maintenance expenses in upgrades and application changes. Databases of leading RDBMS
vendors now are providing extended data support to store complex data types such as images,
videos, CAD drawings and spatial information together with the corporate character data. They
are known as object-relational databases or universal servers.
At the same time GIS vendors are providing spatial middleware solutions to use RDBMS to store
their spatial data and allow traditional corporate users to perform geographic queries. In this
moment we can say that both are partial and incipient solutions. The one coming from the
RDBMS side and the other from the GIS vendor. For the short term, and if the company has
already a big investment in GIS applications, the solution is the one that offers the GIS vendor by
going through the middleware. In the long term the solution will be the one offered by the
database vendors to manage the data. The GIS software will mainly be used to perform spatial
analysis and GIS functions.
One interesting suggestion is to save the graphics information in tabular format. For example
pipeline alignment information can be saved in tabular format and the graphics can be generated
from there. Actual updates can be done directly in the database and any map using that
alignment can be regenerated from there. As an additional advantage, this tabular information
can be more easily integrated with corporate users using traditional tabular type of tools.
Communications
GIS applications can be local, remote, mobile, or a combination of them. Transmission capacity
has been improving. Optical fiber's bandwidth supports data rates in the gigabit range.
Multimode optical fibers can support transmission rates to 100M bps over distances of one mile
without a need for repeaters. In GIS applications considering that graphics and raster data such
as photos are involved, meaning large transmission data needs, it brings to our attention the fact
that the speed of communications is a major concern for remote and mobile applications.
For local applications, where the servers are in the same building, and where general
transmission rates for the end users are in the range of 10M bps the response time is acceptable.
For remote applications normally connected using T1 lines with 64K bits of capacity, difference
in transmission rates is substantial. The design of the application has to take into consideration
this limitation and save or distribute those graphic files or themes more used in the remote
locations to the servers located therein order to minimize transmission times.
If we need to enable mobile workforces to access important and often confidential information,
in addition to the transmission rate concern for wireless applications we need to incorporate
security capabilities in the design. This wireless solution will normally reside in the corporate
intranet with efficient data compression algorithms and the data streams secured behind
firewalls. The transmission rates in this case goes down to 33.6 kbps or 19.2 kbps.
Actually at the current speeds, e-mail or messaging type of applications works ok. For graphics
applications this solution will be very slow. One possible way to overcome this difficulty will be
by having the graphics residing in the laptop, and receiving only the tabular data and minimal
graphics information from headquarters.
Conclusion
To be able to manage these different technologies that are used by GIS, we need to have an
understanding of what are the advantages, and the technical and economical limitations of their
use. Each technology has a set of factors or variables that will impact their use when used in
conjunction with GIS. These concepts that I have emphasized along the paper will help us in
making a better decision in their use.
A combination of theory and practice is necessary to grasp the concepts. A recommendation to
acquire practical experience without jeopardizing any project, is to implement small pieces of
new technology in each project, or by doing small pilots to test the technology.
