Mapping automation using GPS, GIS, and programming
Present Compilation Process
New technologies are also improving the field data collection. Global Positioning System (GPS)
pilot projects have shown that it is possible to bring digital highway positional data back from the
field and enter it directly onto the map design file.
The GPS highway alignment data has been used for the collection and verification of the county
highway improvement packages. The Field Inventory Team is able to bring back to the Mapping
Team the exact alignments of the new county roads and is also able to verify the positional location
of new features not contained on any aerial imagery. This new GPS unit can also be used to verify
positional accuracy of the existing mapping now maintained by the SHA.
SPOT Satellite Imagery was purchased in the effort to obtain current, accurate and affordable
compilation o~ data “col~ection”w& perfo”rtriid in a’manu”al fakhion. It was “p6ssible to create map~
aerial photography. An added bonus to the increased accuracy was that they were referenced to the
digital map base eliminating the need to use projectors or cameras to change scales.
From the first day the Mapping Team received the SPOT data they began using it. It has become a
valuable information source for correcting roadway alignments for the local road systems. The new
county road improvements are also easily digitized from this information.
Now when the road improvements are reported they are still field-verified by the SHA’S Data
Collection Team. The Data Collection Team updates the official road inventory if the report is
correct. If the improvement is new construction (or new location), the road alignment is now
GPS collected. The field information is then taken back to the office where the inventory data is
still entered into the master data base and GPS collected line work is post processed. After this
process, all the new data is sent to the Highway Mapping Team and the corrected GPS data is
referenced over a grid map. Other sources of information may still be referenced, such as tax
maps, subdivision maps, survey data, access permits, aerial photography and newly added SPOT
Satellite Imagery. All of the new information is then placed on a correction copy of the map and
then heads-up digitized into the correct grid map file.
The team has selected the Trimble Aspen Pro System which is capable of dynamic data collection.
This equipment and software has been successfully implemented to collect alignment data and
inventory data at near highway speeds, and to be compatible with the Intergraph equipment and
software the SHA now utilizes. The Aspen Pro System provides everything needed for efficient
collection and processing of GPS/Inventory data. It will display our map as the background map on
the notebook computer so our field staff can easily navigate to the data collection sites, and collect
data directly using the grid map as the base. This will save time eliminating transcribing from the
paper forms and diagrams. The Aspen Pro System is Microsoft Windows compliant.
Proposed Compilation Process
The proposed compilation process has two main objectives. First to update the map base within a
timely fashion and to compile the majority of the data digitally. The two objectives are closely
related. The major work efforts for the map base update are the visual scanning of aerial
photographs for new features and adding the county improvements to the map base. Other feature
data collection which can be automated now include adding new political boundaries (annexations),
park or other delineated boundaries, and locating new roadway alignments from the construction
plans (state system).
A MicroStation MDL program HWYTOOL was developed by CADDScan Engineering, Inc. to
provide a user friendly environment that is fully integrated in MicroStation for the purpose of
importing and updating GPS data into Statewide Grid Map files. The program is developed for
three major objectives. The first is to import GPS data into MicroStation .dgn files. Second is to
assist querying and reviewing attribute data associated with road line work, and the third, to
automatically update the Statewide Grid Map files.
When the program imports the GPS data into MicroStation, this process will result in a time saving
later in the map updating process. The collected GPS alignment data is converted into graphic
elements and the attribute data is populated into a database table. An association between the
database and the graphics element is established. All the graphics are automatically placed onto
appropriate levels and their color, line style and weight are changed according to the existing file
setting scheme. This greatly reduces the manual editing required for map updates. In addition, all
the attribute data collected in the field are linked to the graphics. Querying, reviewing, and editing
the data become easy through a dialog box. The stored attribute data can also be easily placed as
labels on the roads on, or exported to text reports.
The GPS data is still overlaid against existing Grid Maps, aerial photography and SPOT satellite
images to insure quality. After the verification is finished, the grid map updating module can
automatically update the map file into appropriate Grid Map sheets. There are more than one
hundred map sheets that cover the State of Maryland. First, the program “cookie-cuts” the road
alignment data along the grid map boundaries, then finds the map sheets they belong to, and
updates them. This eliminates all edge matching problems.
The Highway Information Services Division is now investigating Electronic Road Inventory to
automate downloading GPS data into our databases. This would eventually save more time with
the maps and database updates collected and performed in the same process.
Conclusions
Several new technologies will improve the map base update cycle. A few years ago the cycle was
three (3) years for maps, mainly due to the manual methods of mapping. With the completion of
the digital grid maps, the maps can be updated faster than the data can be collected. At the present
time the update cycle has been reduced to 18 months. It is hoped that within the next few years the
cycle can be reduced to less than one (1) year.
