Etrex Vista

[+Phil the phone man]

My new Etrex Vista C shows the tracks off the streets of the Mapsourse maps. It shows the tracks 107 ft south and 47 ft west of the streets. I tried recalibrating the compass to no avail. Got any ideas??

[+royta]

It could very well be the software itself. Near my house, there is a section of freeway and old highway (before freeway was built) that run parallel. The old highway starts out on one side of the freeway, crosses under the freeway, makes a long sweeping arc, and crosses back under the freeeway about 1 1/2 miles down the road. US Topo gets the two roads backwards. It is right here.

 

 

Temescal Canyon Road and I-15

Edited January 5, 2005 by royta

[Curious George]

My new Etrex Vista C shows the tracks off the streets of the Mapsourse maps.  It shows the tracks 107 ft south and 47 ft west of the streets.  I tried recalibrating the compass to no avail. Got any ideas??

What was your EPE at the time?

[Neo_Geo]

If you're using WorldMap, Topo, Roads & Recreation, MetroGuide 4 (or earlier), then it's a limitation of the accuracy of the maps themselves.

 

Note below - the waypoint in City Select 5 is right on Conwell Drive. Then compare the same waypoint in Roads & Recreation 3.03.

Also note other differences like distance from Conwell Dr. to Brentleigh Ct.

 

Edited January 5, 2005 by Neo_Geo

[+Sputnik 57]

Boy, that's a big discrepancy. Are you using the right datum?

[+Couparangus]

What version of Mapsource are you using, Phil?

[Neo_Geo]

Boy, that's a big discrepancy.  Are you using the right datum?

It appears to be 311 feet! All I did was change the product selection from City Select to R&R. No other changes were made.

Edited January 5, 2005 by Neo_Geo

[+Alan2]

All maps are inaccurate.

Edited January 5, 2005 by Alan2

[Neo_Geo]

All maps are inaccurate.

Yeah, but some are more accurate than others. I've found the NavTech data in MetroGuide USA 5 and North America City Select 5 to be VERY accurate!

 

With Roads & Rec, I was finding discrepancies like that everywhere I went. I've long given up on trying to find any such problems with NavTech data

[+Sputnik 57]

Boy, that's a big discrepancy.  Are you using the right datum?

It appears to be 311 feet! All I did was change the product selection from City Select to R&R. No other changes were made.

Actually, my datum question was directed to The Phone Guy. NG's map to map comparison is pretty compelling.

 

My GPSr occasionally shows me off the freeway, but they are moving so many freeways around Houston these days, it would be hard for any software vendor to keep up.

[+Phil the phone man]

My old Etrex Legend with Roads & Recreation ver 3.0 were right on the money (except for road moves, etc.). My new Etrex Vista C with the same Roads & Recreation ver 3.0 are off by 100 feet or more no matter what. Can I change anything to get them to line up? I am a boater and I am embarrased to show anyone we are boating on land following the river. I am using The map datum WGS 84 on both.

pbryan@sigecom.net

[+Prime Suspect]

Boy, that's a big discrepancy. Are you using the right datum?

The datum shouldn't make any difference. The coordinates didn't come from an outside source. They were taken by the GPS itself. These are tracklogs, right?

 

Uploadable maps don't store every twist and bend in a road, especially on limited access highways. For car navigation, it's pointless and uses up a lot of memory. Any place two road intersect should be pretty close to being correct. But otherwise, it's not uncommon for it to deviate a good bit.

[peter]

My old Etrex Legend with Roads & Recreation ver 3.0 were right on the money (except for road moves, etc.). My new Etrex Vista C with the same Roads & Recreation ver 3.0 are off by 100 feet or more no matter what.

Was this a side-by-side comparison? If so, did the lat/long readings of the two units agree when they were showing different positions on the map?

 

Roads&Rec maps come from an older TIGER database created by the Census Bureau to have enough accuracy for their poll takers to find and tabulate addresses, but 100+ foot errors are very common. I'm frankly much more surprised to hear that you didn't see errors with your old Legend than that you do with the new one.

 

Upgrading to CitySelect-NA v6 would give you much more accurate street maps as well as supporting more of the features available on your LegendC - address searches, auto-routing, business searches, etc.

[+Alan2]

All maps are inaccurate.

Yeah, but some are more accurate than others. I've found the NavTech data in MetroGuide USA 5 and North America City Select 5 to be VERY accurate!

 

With Roads & Rec, I was finding discrepancies like that everywhere I went. I've long given up on trying to find any such problems with NavTech data

I'm curious how far they are different - one from the other. But I don't have either of these. COuld you create a waypoint at a street interesection on one program and then switch to the other program and measure the distance to the interesection from the waypoint? Try that in a couple of different cities for comparison. what footage are you coming up with?

 

When I tried this using my Garmin Topo vs Metro vs R+R I would find differences up to 120 feet.

Edited January 6, 2005 by Alan2

[BlackBeard Pirate]

I've been trying Mapsource 3.02 with R&R maps version 2.01 on my Vista and its usually accurate, but they are outdated and inaccurate in places.

 

What do you all think about Mapopolis maps? I haven't had a chance to try these maps out with my gps because I'm still waiting for a usb to pda cable, but these maps look really awesome!!!

 

Where do these maps come from? I'm thinking that most companies get their maps from one of only two or three sources. Who makes the most accurate maps?

[peter]

Where do these maps come from? I'm thinking that most companies get their maps from one of only two or three sources. Who makes the most accurate maps?

PDA Buyer's Guide says: "Mapopolis offers three different types of the maps. In addition to the Platinum maps we’ve tested here, there are also the Basic and Enhanced map packages. The map data source for the basic and enhanced maps is the US Census Bureau's TIGER '00 database. The map data source for the platinum maps is licensed from Navigation Technologies [ed: now called NavTeq]"

 

NavTeq is the source for many of the current street maps used in standalone GPS receivers, being used in Magellan's DirectRoute and new 3DTopo and in Garmin's MetroGuide, City Select, and City Navigator products. It's also used in most of the dedicated in-car navigation systems.

[BlackBeard Pirate]

Thanks peter... I'm waitin for a cable to connect my etrex yellow to my pocketpc with mapopolis.... I think im gonna REALLY like mapopolis! especially for the $!

[Neo_Geo]

I'm curious how far they are different - one from the other.  But I don't have either of these.  COuld you create a waypoint at a street interesection on one program and then switch to the other program and measure the distance to the interesection from the waypoint?  Try that in a couple of different cities for comparison.  what footage are you coming up with?

 

Yellow = City Select 5

Gray = Roads & Recreation 3.03

 

Chesterfield, Virginia (A suburb of Richmond)

1. N37 22.702 W77 30.544

2. N37 22.728 W77 30.512

3. N37 22.782 W77 30.384

4. N37 22.666 W77 30.497

5. N37 22.671 W77 30.387

 

 

================================================

 

Cary, Illinois (A suburb of Chicago)

1. N42 12.038 W88 15.474

2. N42 12.056 W88 15.270

3. N42 11.968 W88 15.165

4. N42 11.912 W88 15.075

5. N42 11.809 W88 15.247

 

Edited January 7, 2005 by Neo_Geo