DATUMS

**Pathfinder Office and ArcView - Can we all get along!**

**Background**: Datum's and projections are tough! GIS folks who use
Trimble GPS equipment have at least a "soup-to-nuts" approach when
integrating their data into ArcView. I hope to show some tricks on how
to get your Trimble Pathfinder Office equipment to coincide with our NPS
ArcView world. For new Pathfinder users, this may be one of the first
times you come directly up against choosing the datum for importing to
ArcView.

First of all, Pathfinder Office software is very powerful. The datum and
coordinate system embedded in the software are very robust. With
robustness, comes complexity. As with all GPS systems, the greatest
error in the budget comes from the User!. In both export and Import
modes, you will need to select a Datum to export or import your data.
The Datum transform engines are equivalent to full-blown ARCINFO - the
trick is selecting the correct datum. In this discussion, we are
assuming your GPS field data will eventually end up in the NPS ArcView
world.

EXPORTING GPS DATA FROM PATHFINDER OFFICE FOR DISPLAY/USE IN ARCVIEW:

You should select Latitude/Longitude and NADCON (Alaska) for all your
shapefile exports. This way the best datum transform occurs on your
field collected data (NADCON) which is equivalent to ArcINFO NAD27
transform. See Figure 1.

Figure 1.

![](media/image1.jpeg){width="3.3625in" height="3.4506944444444443in"}

\*\*\*\*This is data you may one day give to the GIS team for eventual
incorporation into the park dataset\*. Please include the export
textfile\*\*\*\*\*\*\*\*\*

Another document entitled "PFExportAV.doc" provides detailed setup
information for your shapefile export needs.

EXPORTING DATA FROM ARCVIEW INTO PATHFINDER OFFICE FOR FIELD NAVIGATION

With SA turned off, users are finding CA code equipment powerful
navigation tools! PLGR users have known that NAD27Alaska Datum is the
datum of choice when navigating to ArcView generated waypoints. Trimble
users can navigate to ArcView generated waypoints or shapefiles now!
Geo3 users can update this information as well.

There are several ways to generate data from ArcView for Trimble
waypoint files (WPT). In any of the cases, you must first set the MAP
view in Pathfinder Office to the coordinate system equivalent to the NPS
ArcView world. Which is...quiz question.... NAD27, Latitude Longitude.
So, under Options/coordinate system, select Lat/Long, NADCON (Alaska)
See Figure 2.

Figure 2.

![](media/image2.jpeg){width="3.286111111111111in"
height="3.6006944444444446in"}.

-   For one or two points, you can simply use the Return cursor
    coordinates tool in Arcview ![](media/image3.jpeg){width="0.325in"
    height="0.275in"} and copy/paste the coordinates into the Waypoint
    Edit box (File/waypoint/new/create). Here is a gotcha, you must
    enter a N at the end of latitude and a W at end of Longitude for the
    waypoint to be valid! If your entering Decimal Degree LAT/LONG data,
    You must include the (-) negative sign in front of the number (e.g.:
    54.667676 and -149.l56565).

![](media/image4.jpeg){width="2.4479166666666665in"
height="2.048611111111111in"}

-   For multiple waypoints, you could generate a point shapefile in
    ArcView, then populate the points with the XY coordinates (under
    AlaskaPak/Add XY Attributes). Export the tabular data and manipulate
    into a format for import into Pathfinder Office waypoint format.
    Search on ASCII and then ASCII import under Pathfinders Help for
    format specifications.

-   Once your waypoint file is saved the last thing you need to do in
    Pathfinder Office is send the data to your handheld. Under Data
    Transfer, select \"Send\" and select Waypoint as Data Type. Be sure
    to name your individual waypoints appropriately (up to 10
    characters) like trailhead1 or bear3. This way, in your datalogger,
    you can more effectively navigate to multiple objects in the map
    window!

Most important in navigation, is sticking to the datum from which the
data came from! In Trimble GPS equipment, the datalogger you hold in
your hand will auto transform any inputted data on the fly! You can
import a LATLONG NAD27 Alaska waypoint and navigate to that waypoint in
UTM!!!!! As a result, this on the fly transformation does impart small
rounding errors that may or may not be significant. Recall, however,
that the accuracy of data pulled from ArcView and a DRG is
[+]{.underline} 38meters! Now, your navigating to a point with a
[+]{.underline} 38 meter error on a handheld GPS with an accuracy of
[+]{.underline} 10 meters! Will the GPS get you to your point? Yes! -
but within the original 40meter bubble of error. Will the GPS allow
navigation to a needle in a haystack? No.

It\'s up to you to use the GPS as effectively as possible. Hope this
helps.

NOW FOR SOME OFFSHOOT PATHFINDER TRICKS THAT GO A LONG WAY:

-   In all your export functions, save that little export text file that
    is automatically generated with each export. This is great metadata
    file which includes many configuration parameters. Drag this file
    around with the shapefiles for handoff to your GIS coordinator
    -he/she will love you for this!

```{=html}
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```
-   You have no control on naming a shapefile- yuck! You can control
    where a shapefile is exported by creating a subfolder on the fly in
    the output folder box (see trick1.jpg). This way, managing is easier
    when conducting multiple exports. Then, in ArcView, using the
    shapefile manager under File/Manage Data Sources pull down menu, you
    can rename your shapefiles.

Trick1.jpg

![](media/image5.jpeg){width="3.376388888888889in"
height="3.490972222222222in"}

-   Create an Export Setup that defines various configuration parameters
    for any of your export functions. Trick2.jpg shows how my \"DD
    shapefile\" setup automatically defines Lat/long and NADCON(alaska).
    To define a new setup, first choose a sample export setup (eg.
    Sample Arcview Shapefile Setup), then Press New Setup tab. Rename
    the setup like \"DD NADCON Shapefile\" and then step through all the
    configuration tab for that setup. See Trick2.jpg

![](media/image6.jpeg){width="3.0458333333333334in" height="3.1in"}

Trick2.jpg