Gpsr For A Mapmaker?

[+aerospacecase]

I received the following in an email. Since I don't consider myself an expert in this area, I thought I would post this on the forums and give the whole GPSr community a chance to respond.

 

"The following P.S. is from a guy I've been talking

to. He is a map maker and makes maps similar to Tom Harrisons maps.I

told him I would ask around the Geocaching circle and your the only one I

have confidence in for an educated response. Any thing come to

mind?.... P.S. I am in the market for a GPS that offers mapping

capabilities. I am considering doing another map of

this area and would like to incorporate GPS into the

mapping process. I'm looking for a unit that can

track distance and trail configuration and then allows

me to download back into my MAC at home to show the

exact trail scope. I'd be going on trips of up to 10

days so memory and battery strength are important

factors as well. Any suggestions?"

[peter]

As usual no one unit is best at everything asked for so some compromise is required.

 

Lowrance would be best at keeping large numbers of trackpoints and storing them on the SD memory card but unfortunately their models don't keep track of altitude data (or timestamps) in the tracklog so I think they're ruled out on that score alone.

 

Magellan models also let you store tracklogs to the SD card and include altitude and time data. But only their eXplorist 600 includes a pressure-sensor based altimeter and that model has issues on long trips with the lithium battery (the Platinum only uses pressure data for the barometer). Also the eXplorist 600 does not integrate pressure-based and GPS altitude data to give the best of both.

 

The best altitude data is available from the Garmin models that have a pressure sensor (the Vista, VistaC, 76S, 60cs, 76cs). These use the GPS altitude data averaged over an extended period (time constant of about 30 minutes) to automatically recalibrate the pressure-sensor. This compensates for weather-related changes in pressure and gives significantly better altitude data than other GPS models without the need to manually recalibrate. The newer of these (VistaC, 60cs, 76cs) have excellent battery life and run on a pair of AA cells (regular or rechargeable). Unfortunately they don't have memory expansion, but the active tracklog of 10,000 points should be enough for at least a week long trip and should be able to handle the 10 days if the track usage is watched and the resolution adjusted as needed.

Since the data needs to go to a Mac I wouldn't pick the VistaC which only outputs in Garmin's own protocol and the USB port has some compatibility issues with Macs. The 60cs and 76cs also support NMEA protocol over RS-232 and there are Mac programs that handle that (an RS-232 to USB adapter is also required).

[stevesisti]

I received the following in an email. Since I don't consider myself an expert in this area, I thought I would post this on the forums and give the whole GPSr community a chance to respond.

 

"The following P.S. is from a guy I've been talking

to. He is a map maker and makes maps similar to Tom Harrisons maps.I

told him I would ask around the Geocaching circle and your the only one I

have confidence in for an educated response. Any thing come to

mind?.... P.S. I am in the market for a GPS that offers mapping

capabilities. I am considering doing another map of

this area and would like to incorporate GPS into the

mapping process. I'm looking for a unit that can

track distance and trail configuration and then allows

me to download back into my MAC at home to show the

exact trail scope. I'd be going on trips of up to 10

days so memory and battery strength are important

factors as well. Any suggestions?"

My only comment would be to make sure you have a provision for an external antenna, especially if your going to incorporate the data into a map. All units see improved accuracy with an external antenna, specifically under trail conditions where he will most likely be.

 

My 60cs shows variations from track to track of well over 60 ft under tree cover, an external antenna improves this dramatically.

[+GOT GPS?]

GPS for a Mapmaker:

 

I would think the Explorist XL that is coming out, would be the good choice for that.

[+NinjaMonkey]

I can recommend some Mac software. The best would probably be MacGPS Pro. It is only $39 and well worth it. Check macgpspro.com for details.

 

An external antenna is almost a must. I purchased a Gilsson for my Garmin 60CS for only about $20 and it works amazingly well.

[+Renegade Knight]

For map making the tracklog is king.

 

The more points and detail your tracklog can give you the more accurate it is and the better information you will have for maps.

 

Beyond the tracklog I don't know how else you would use a GPS for a mapmaking process.

 

I've read comparisons of tracklocks (and posted them before though I don't recall where) and one software company flat out says Garmin is the best overall for their Tracklogs. Magellans especially the older models have crappy track logs. It's possible the newer explorists have fixed some of the issues that kept track logs from showing where you have been. If I do find the link for the company, they had graphics showing the tracklog comparisons.

 

Edit: I agree with the reccomendation for an external antanea. Better info in, better info out for any GPS.

Edited September 14, 2005 by Renegade Knight