Untitled Document

ArcPad

Hey look, this is what will eventually be the how-to for using ArcPad with a GPS. Currently it is in a massively rought-draft configuration.

For use in ArcPad 6.0, raster files must be accompanied with a projection file (.prj) of the appropriate projection. This can be created by assigning a projection to the file under ArcInfo/View/Map (let me know if you figure how to do this because I haven’t) or by copying and pasting a generic projection file from the folder of them in the ESRI directory, and assigning the entire “map” that projection under ArcPad.

Places the .prj file CAN be:
Storage card/my documents

Places it CAN’T be:
Storage card/coordinate_systems

FYI there is a more extensive selection of generic projection files in the ArcGIS program directory (eg. C:\arcgis\arcexe81\Coordinate Systems) than in the ArcPad program directory (C:\ESRI\ArcPad 5.0.1\Coordinate Systems). Why? I don’t know.

They also require a world file, in the “.bpw, .jgw, .tfg, ect….” naming format.

FYI this format is based on the using the first and third letters of the three letter extension plus a “w”. Thus JPG becomes JGW.

FYFI world files are composed of two Cartesian points in text format. The first is an X,Y pointing to a single pixel in the raster image (usually 0,0) and the second is a geographic coordinate to be assigned to that pixel, in whatever projection has been indicated in the separate coordinate file/projection file. Or is it the other way around? The geographic locations of all the other pixels are extrapolated from this point and the projection.

Files to be viewed must be in what folder?

Once there is a projection file assigned to the map or the individual file, the “GPS tools” button on the toolbar will become enabled, and you will be able to display the GPS location cursor on your map.

To record GPS data you must first crate a new shapefile in ArcPad of the appropriate type (i.e. line, point etc… it will ask when you choose “create shape file” from the file button on the toolbar”) You can then use the GPS edit button to begin recording GPS location data.

CHECKLIST FOR PREPARING MULTIPLE FILES FOR USE IN ARCPAD

Does not yet exist. Sorry.

Logged stuff so far:

Changed baud rate on ArcPad to match that on ProXR receiver (ecudaor one? Other way around – matched receiver to arcpad - ? both to 9600?)

Changed (parity?) on receiver to match that which ArcPad has* to be set to, ie. Even.

*according to email from ESRI support.

This appeared to clear up the communication problems.

Subsequently wrestled with projection (.prj) files. Having trouble producing a .prj file to go along with the registered bitmap of campus map in order to confirm accuracy of received position.

Discovered possible work around – associating a projection with the “project” manually rather than having one exclusively for the the .bmp. Problems remaining:

10-Jan-02 Once location has been received, can no longer see map layer, even when attempting to zoom to extent. Am I REAALLLY far off with the location, or is it not displaying the image?

Possible solutions: check that projection information syncs up 100% between receiver/image/assigned projection

According to GPS info window on ArcPad, all satellites are receiving at high error levels (displaying red bars). All statistics regarding DOP etc. are not displaying at all. This is true even though the program is recording positions and apparently generating a tracklog (check this!). These positions seem accurate relative to each other, but since the image apparently doesn’t display, I can’t verify their absolute accuracy.

Possible solution: check the tracklog.

18-Mar-02 Successfully (?) placed georectified campus map on machine, activated in arcpad using generic .prj file copied from acrgis catalogue. Received gps locations and displayed tracklog, however all gps locations appear ~10-20m to the W of location on map. Still no satellites displayed in skyplot and SNR numbers all still show in low reds.

Assessment: create a shape file with lines and use it to test logging against a known-good shapefile of the campus (doq?) in arcgis.

Relevant Forum Messages

Subject ArcPad 6.0 Release
Author Potri adian
Date Nov 05, 2001
Message When is the release of ArcPad 6.0 expected?
We need to plan our work accordingly.
Kindly reply.
Potriadian

Subject Re: ArcPad 6.0 Release
Author Shane Clarke
Date Nov 05, 2001
Message The release has been delayed. We are now looking at a release early next year, probably February.

Subject Setting Projections
Author Tim Marriott
Date Nov 03, 2001
Message I've read the posts about setting the datum for the GPS receiver to match the datum on the geodata and I still have some questions.

1) My shapefiles and MrSid images are State Plane 1983 - Illinois East. Do the shapefiles need to have a *.prj file with them? (When I open my Layers control in ArcPad and select the Projection icon, the screen shows SP 1983-IL East)

2) How can I tell which datum to choose in the GPS setup? My iPaq only has enough room to show the first 6-8 characters of the datum names and there are many that look alike.

My GPS receiver works and I've got the PocketPC communicating with the receiver. If I can get these projections lined out I think I'll have the job licked.

Thanks,
Tim

• top print reply
Subject Re: Setting Projections
Author Shane Clarke
Date Nov 05, 2001
Message 1. Your shapefiles do not need a .prj file if a projection has already been defined for your ArcPad project - as it appears to have. However, I recommend that all shapefiles have associated .prj files.

2. This is a little tricky, and something we have improved in ArcPad 6.0. The easiest method is to select a datum and then use the associated Info button to view the details of the selected datum.

Subject AP6 recognize L1/L2??
Author Darris Friend
Date Apr 08, 2002
Message Our organization is ready to move to dual freq GPS. AP5 works great with our single freq GPS reciever and our own base station.

Does AP6 work with RTK and take advantage of dual freq GPS units? We prefer to avoid post processing the RTK.

Thanks

• top print reply Subject Re: AP6 recognize L1/L2??
Author Tim Price
Date Apr 08, 2002
Message Hi,
Yes, ArcPad can take advantage of dual frequency and RTK GPS units. These units output NMEA (or TSIP) coordinates that have been calculated by the receivers using the information available to them. No post processing is required using this method.
Cheers,
Tim.

Subject Saving GPS Data as a Shapefile
Author Craig Greenwald
Date May 10, 2001
Message When you collect GPS data in ArcPad, you are collecting this
data directly into a shapefile. So, the first step is to choose the
shapefile. This can be an existing shapefile to which you want to add
GPS data, or a new shapefile that you create in ArcPad (using the New
Layer tool).

Once you choose the shapefile, add it as a layer in ArcPad (using the
Add Layer tool) and make it editable (by checking the pencil checkbox
in the Layer dialog)
If you create the new layer (shapefile) in ArcPad, this step is done
for you.

Now, activate your GPS and click the appropriate Capture by GPS tool
(Point, Line or Polygon).

Capture the desired data. Once you are finished, transfer the
shapefiles to your PC and open them in ArcView.

Please note that only Ashtech, Magellan and Trimble GPS receivers are
supported for data capture in the U.S. at ArcPad 5.0.1. This
restriction will be removed in ArcPad 6.0, due out this July.

Hugh,

Wanted to follow up on ArcPad document you're working on. It can live
here (on the pc its the X: drive):

/proj/www/labresources/documentation

I'd like to start a cstars fieldwork users guide binder from the
various documents we'll end up writing, all of which will live in the
above location.