|
Upon returning
from the field, each member of the data collection
team needs to download the data from their GPS
and load it into the relation database management
system. This may be a direct download to the database,
or it may involve more steps. For the purpose
of this protocol set, we will use more steps to
ensure data quality.
This is more likely to be necessary if you are
using members of a community who have not had
much training in emergency procedures or GPS units.
To begin with, download the raw waypoint and track
data from GPS to a text file. Next, label this
file with the date of data collection (in reverse
format), the letter “r” (indicating
raw data), underscore, and first waypoint name
(i.e. “060416r_ 0101011). By including the
first waypoint in the file name you will be identifying
the GPS (possibly the user) and the area surveyed.
Next, import the file into a spreadsheet. This
will allow for easy and efficient data checking
and editing if necessary, essential for quality
control. Each user should be responsible for checking
their own data for accuracy. If necessary, this
should be done with a member of the GIS team.
Next, import the “clean” data (waypoints
and tracks) into the database. All of the waypoints
can go into a single table. The waypoint naming
convention ensures that each waypoint can effectively
be used as a primary key value. Additionally,
the naming convention allows for extracting information
related to a single GPS or survey area. The database
administrator (DBA) may want to import track data
into tables designed for each GPS. This would
be the easiest and most effective way to distinguish
one set of GPS tracks from another. |
| Data Management |
The RDBMS
will need to have a set of reference tables and
transaction tables. The example set listed below
uses the Unalaska Trail Mapping Project (UTraMP)
model. The UTraMP model is particularly useful
in that it is the easiest to understand and modify
for single attribute acquisition, like stream
surveys or search and rescue operations. |
| UTraMP Reference
Tables: |
GPS reference
table (tbl_GPSId)
• cGPS_ID (GPS receiver Id number in the
database)
• cGPS_Make (Manufacturer)
• cGPS_Model (Model of GPS)
• cGPS_SN (Serial number)
• cGPS_Owner (Owner or operator)
• cGPS_Name (Written on the case of the
GPS, i.e. “CRC-1,” in this case it
meant the first GPS unit for that organization.
Others were labeled CRC-2, CRC-3, etc.)
Trails reference table (tbl_TrailInfo) •
cTrail_ID (Trail ID number in the database)
• cTrail_Name (Name)
• nTrail_Length (the trail length in linear
distance)
• nTrail_Time (the amount of time it takes
to go out and come back)
• cTrail_Difficulty (on a scale of 1 ~ 3)
Trail Attribute table (tbl_WayPtsId)
• cTrail_AttributeID (This was the primary
key value for the table and the waypoint key value
for the naming protocol)
• cTrail_AtributeDescription (This was the
description of the ID value, i.e.: 1 = Start of
trail; C = Cabin. Note that the Attribute ID was
a mnemonic to the description. |
| UTraMP Transaction
Tables: |
GPS Waypoints
table (tbl_WyPts)
• cType (this field is information generated
by the GPS unit to indicate whether the data is
a waypoint or track point)
• cWypt_Name (a user defined field, in this
case, this is where the attribute information
for the specific location is stored)
• Figure 2, Data flow from the GPS unit
to the RDBMS
• nLat (Latitude, generated by the GPS receiver)
• nLon (Longitude, generated by the GPS
receiver)
• dtTime (Time and date, generated by the
GPS receiver)
GPS Tracks table (tbl_Trax)
• cType (this field is information generated
by the GPS unit to indicate whether the data is
a waypoint or track point)
• nLat (Latitude, generated by the GPS receiver)
• nLon (Longitude, generated by the GPS
receiver)
• nAlt (Based on the GPS datum, generated
by the GPS receiver) |
 |
| Data Manipulation |
Data manipulation
is done through the use of queries: either by
combining tables or queries of related data and/
or running calculations on them. In this database,
the common data manipulation is parsing the Waypoint
Name field (cWyPt_Id) and “joining”
or linking the newly created parsed fields with
the primary key fields of the associated attribute
table.
Figure 3, is an illustration of the data flow
for the Selandang Ayu Data Model for oil spills.
The illustration is simplified from the actual
RDBMS. In the actual RDBMS all data tables become
queries before any relation is applied. This is
done as a precaution to protect the integrity
of the original data. |
 |
| Data Analysis |
At this
point, the geospatial data is ready for visualization
in a GIS. Now the management team can see what
areas have been surveyed, who surveyed them and
what was found. Most likely, you will have had
to acquire or create our own base maps. You will
have had to ensure that all of the maps and data
are in the same projection with the same datum
and you will have had to create symbology for
the different attributes of your data.
At this point, you are also ready to perform advanced
analysis on your data. From here you can buffer
points and lines; and use other tools that will
allow you to clip, merge and intersect your GPS
data with other map features. Also, if this were
a disaster, you could use advanced statistical
calculations on the collected data in order to
evaluate the nature and spread of a given contaminate.
If this were a SAR operation, a view shed analysis
could be performed from the elevation of the hiker
and a maximum area of observation could be obtained.
A coastal resource assessment protocol has been
investigated using this protocol. As of this time
it is still in development. It was originally
a modified version of the Oil Spill model, but
going through a list of items and plugging them
into a GPS was overly tedious and time consuming.
Possibly, a better model, soon to be tested, involves
limiting the number of items of concern to subsistence
species or indicator species or both. In this
case the data field would identify either a Boolean
value of either presence or no presence, or presence
and quantity. |
| Summary |
The elimination
of Selective Availability and the incorporation
of WAAS and
DGPS have greatly increased the accuracy and precision
of the consumer-grade GPS. This new, high precision
tool has the potential to greater xpand
the resources of communities to respond to challenging
situations that require immediate geospatial information.
Additionally, having this information and the
knowledge that comes with it, as an emergency
unfolds, can empower a community to make better
decisions with the hope of a better outcome. |
| Acknowledgements |
The author
would like to thank Wendy Svarny-Hawthorne and
the shareholders of the Ounalashka Corporation
for their support in the UTraMP project, without
them this protocol concept and method could not
have been so rigorously field tested. Further
thanks go out to University of Alaska Fairbanks
professors, Anupma Prakash and Michael Sfraga,
both of whom gave their time and support to write
up this project. Anupma was kind enough to read
and comment on several drafts. Finally, Tom Heinrich
from the Geographic Information Network of Alaska
encouraged this project and helped clean up several
working drafts of this document. His kindness
and talents are greatly appreciated. |
| |
 |
Robert Mikol
GI Network of Alaska, University of Alaska,
Fairbanks
rmikol@gi.alaska.edu |
|
| |
| <<...Back |
| November 2006 |
| |
|
|
|