BGSU Digital Mapping
Website
Bowling Green State
University has been using digital mapping in its summer field course since the
summer of 1999. In addition, several on-campus courses use various components
of our system as do faculty in their research. The system integrates GPS
and GIS to produce accurate maps in a digital format.
System
Components
Digital Mapping
in the Summer Field Course Curriculum
The projects are organized
to progressively introduce students to digital mapping. The first two
mapping projects are done using traditional methods of mapping on topo and air
photo basemaps. GPS is introduced in a one-day project where students
map a surveyed triangular course using pace and compass, GPS single reading,
GPS averaged reading, and differentially-corrected GPS. Students plot
the location of the three stations as determined by each method on a single
basemap to see the advantages and limitations of using GPS for positional information.
The afternoon is spent mapping a single contact with a series of GPS waypoints,
downloading the data, and plotting them on a topo basemap. The next three mapping projects have
the students mapping on DOQ and/or DRG basemaps on Pocket PC computers using
ArcPad. In addition to drawing contacts, students collect structural data
and make field notes on the handheld. A stereonet program on the handheld
allows them to subset their structural data and plot them in the field.
Each night, they download their day's work to ArcView running on a laptop.
After editing the contacts and compiling them with the previous day's work,
they then upload the compiled map back to the handheld for the next day's field
work. At the end of the project, the students print out and turn-in the
finished map.
Example of a Digital Mapping
Exercise - The Sugarloaf Mapping Project
The two files below are those used
in the first full digital mapping project. The Sugarloaf area is located along the
Arkansas River south of Buena Vista, Colorado. The geology consists of
Precambrian plutonic and metamorphic rocks, Cenozoic volcanics, and Quaternary
deposits. The files can be downloaded and installed on a Pocket PC computer
running ArcPad to show how you might set up a project. All the forms for
data collection were designed in the ESRI application builder, but can also
be done using simple scripts available on the ESRI website. The forms used in
this project can be used in any project once the projection files have been
changed to coincide with the base maps being used.
- Instructions - Unzip the Sugarloaf folder on your desktop and copy it to
the Pocket PC, preferably to an external memory storage device like an SD
chip. If you don't already have the ESRI fonts installed, copy the esri_7.ttf
file to the Windows\Fonts folder on your handheld. The PDF file gives
detailed instructions on setting up the files and using the system.
Considerations in adopting
a digital mapping system
1. Hardware
- Pocket PC computer - Just about any Pocket PC computer running the Windows
Mobile 2003 operating system can be used for digital mapping. We
have been using Compaq (now hp
iPAQ's), but I imagine any other brand (e.g., Dell
Axim) would work fine. Some things to keep in mind when looking
for a handheld include:
- Screen size - 3.8" diagonal is really the minimum.
The 3.5" screen that is common on many units today limits how much
you can see. The 4" screens on the higher-end iPAQ's (e.g.,
hx4700)
would be the best choice, but they are pricey.
- Screen brightness - The iPAQ's are known for their bright, daylight
visible screens. The newer, lower cost models (e.g., h2210)
don't have as bright a screen as the more expensive models (e.g., h5150).
- Memory - the system memory (RAM) is not as much an issue as the storage
memory. Most handhelds have 64 Mb of RAM which is plenty to run the programs. You need a device
with external storage capability such as one with a slot for an SD
chip or CF chip. 256 Mb of storage is fine, but with today's
low prices, get 512 Mb.
- Battery life - Our iPAQ's with the expansion
battery pack have no trouble making it through a full day of fieldwork
assuming you turn off the unit when traveling from one station to another.
Without the expansion pack, you need a handheld with removeable, rechargeable
batteries. Get a few extra batteries and you should be fine.
- Ruggedized case - We have had very good luck with the hp
ruggedized case. The case is not waterproof, but will keep your
unit dry in a shower. If you use a CF card GPS receiver, it can
be inserted through a port in the top of the case. The download/charger
cable plugs into the unit through a port in the bottom of the case.
You write/draw on a flexible membrane in the front of the case that sits
behind a flip-up door. I have seen these tumble down outcrops with no ill effects to the handheld inside.
- GPS receiver - we have used the TeleType
CF card receiver with generally good results. It is a bit finicky
sometimes in getting a fix and tends to get unseated from the CF card slot.
We are moving to bluetooth receivers
which give more flexibility. They run off their own battery (rechargeable)
so there is no additional draw on the handheld battery. We have tested
the Delorme Blue Logger and TeleType
16-channel bluetooth receiver with good results. These two receivers
work better in tough conditions (e.g., canopy, harsh topography) and get hot
and cold fixes faster than the CF card receiver. They also eliminate CF card receiver sticking out of the ruggedized case.
- PocketPC system or tablet PC system for digital mapping? - The other system
being used for digital mapping is a ruggedized tablet PC. Check out
the Univ. Michigan's GeoPad website for a
thorough description of this system. The advantage is that you have
a real computer with a large (10") screen to work on. You can map
directly in ArcGIS and skip the ArcPad intermediate stage. You can also
see your map draped over a DEM in 3D using ArcScene. The disadvantage
is cost. You will spend $3-4k for this system vs. $700 for a PocketPC
system.
- Configuring a system - Before you invest in the hardware, assemble all the
components and try them out together, outside in the bright sunlight.
This is even more important when buying multiple units for a class.
2. Software
- Mobile GIS - There's really no choice here. It's ESRI's
ArcPad. The program is simple, robust, and stable. Forms can
be easily created to enter just about any data you can imagine
(see sample files in the Sugarloaf project).
- Desktop GIS - If you use ArcPad, you are pretty much limited to ESRI's products
ArcView
or ArcGIS.
We have tried both and are holding with ArcView for now.
- ArcView - The advantage is that it is relatively simple to use with
the field data generated in ArcPad. Students with no prior GIS experience
can pick up the basics in a one-hour lesson. With detailed instructions
at their side, they can then do everything they need to. The disadvantage
is that they are not building a true GIS with their field data.
The contacts are just lines and no polygons are created. The finished
map, when printed, has no colors for formations. Students must then
hand color the map.
- ArcGIS - The advantage is that students can create polygons for each
formation with whatever attributes you would like. The finished
map is a professional product with full colors. This is the way
maps are produced at most state and federal surveys. Another advantage
is that maps can be drapped over a DEM to show more clearly the relationship
between the geology and topography. The disadvantage is the significant
learning curve once topology (e.g., building polygons) is part of the
job. Our one experience shows that students need much more training
in GIS before they feel comfortable with ArcGIS. The rewards are greater, but so is the time investment.
3. Other sources of information for
digital field mapping
Acknowledgements
This material is based upon work supported by the National Science Foundation under Grant DUE-0126785
to J. Frizado, C. Onasch, and K. Panter.
Disclaimer
Any opinions, findings, and conclusions or recommendations expressed in this material are those of
the author(s) and do not necessarily reflect the views of the National Science Foundation.
