Why Is Curser Is Off The Road?

[spark363]

I have a Magellan Meridian and was wondering why, when I am traveling with it on the road, the curser shows me about 100 feet off the road? Is this normal? I'm wondering if there is a calibration between the unit receiver and the software that I missed. I have only had this for a little while, I'm not too familiar with all the features(I'm learning as i go) I did find one cache and the unit showed me right on it when I found it. So it seemed to work well then.

Edited November 30, 2003 by spark363

[+GOT GPS?]

It's the maps, usually is.

[spark363]

Whoa..I just read the topic line...I must have hiccuped or something there. Don't mind me. Fred.

Edited November 30, 2003 by spark363

[+DustyJacket]

Yup. It is the maps. I've been told the new Direct Route maps are better. I'll post a result when I receive mine. Remember the MapSend products have the whole USA on one CD. The good mapd like NG Topo! have 5 CDs just for the state of Missouri.

 

See this comparison I did:

http://www.dustyjacket.com/geocache/tracks.html

 

BTW - you can edit yur original post and (in the old forums) correct the topic.

Edited November 30, 2003 by DustyJacket

[+embra]

Another consideration: are you looking at a detail map or only a basemap zoomed way in? Detail maps will be more accurate; the base maps are good zoomed out (their primary use is for an overview), but will often be off if you zoom in to the closest levels.

[+EraSeek]

Yes, basemaps are often off, and add in maps (mapsource and mapsend) can often be off too (not as much as the basemaps). On Garmin you have a menu selection for 'LOCK ON ROADS'. This will keep the pointer pasted to the nearest, biggest, road as long as you are traveling along at a certain speed, and until you move away from it for a certain distance.

[spark363]

Yes. it's zoomed in.I'll look at it today out a little to see if if's closer. I'm kind of disappointed in a way. I wanted this to use for traveling with a little more accuracy.Now..is the streetpilot right on? Do they use internal maps specific to the unit, made to be accurate?

[+GOT GPS?]

Navtech maps sold under DirectRoute, City Select, City Navigator, and MetroGuide 5.0 are the best, except there are errors in some places, and that is partly because humans created the mapping.

[+Stunod]

The new DirectRoute maps are MUCH better than the older TOPO/Streets maps. There were about a dozen areas near me that were way off on the old map, but they are corrected with DirectRoute.

[+skeeter-n-lucy]

Can you load detail maps with the direct route like the Map Send???

[+Team GPSaxophone]

My GPSr doesn't have basemaps, but shows my tracklog on the screen. If I repeat the same path (a street or trail) I never quite draw the same line. That's due to the accuracy of the GPSr being only 15-25 feet on average. If your GPSr was accurate to <1 foot you probably would never notice it.

[+Stunod]

Can you load detail maps with the direct route like the Map Send???

The DirectRoute maps are detail maps.

[spark363]

From the first day I loaded the Mapsend Map program I was taken back by how dated the software itself was. I was used to using MS Streets and the early versions of that had it all over Mapsend. This is a crude attempt at a map program. It looks as if it were from the 80s. The only thing it has is the GPS interface. Shame on Magellan. (Thales) Magellan ought to offer registered users updates to the map. There isn't a quarter of the state parks in CT listed on the maps. Even the ones listed are located in different spots than they really are. I'm not buying another map software from them unless I can use it first. It's too expensive to me to pay for another poor substitute of a map program. I won't be duped again.

[+DustyJacket]

I just received DirectRoute.

I did a track today, and compared how they fit to the Mapsend Topo map, National Geographc TOPO!, ExpertGPS/terraserver aerial photos, and now Mapsend DirectRoute.

 

See this UPDATE comparison I did:

http://www.dustyjacket.com/geocache/tracks.html

[+Alan2]

Very nice study, dustyjacket. I believe besides the accuracy of the maps and the GPS at any given time is the conversion factor that occurs in the Datum. Different programs convert the Datum differently so the end result places the cordinates in a slightly different position regardless of the accuracy of the map. It's obvious that Terreserver did a nice job of conversion and of course their picture is "accurate"

 

Did you have NG Topo set for NAD83/WGS84 or NAD27?

 

Tks

 

Alan

[+DustyJacket]

WGS84

[+DustyJacket]

I think one aspect is that the MapSend maps are created on-the-fly.

NG Topo maps are images.

Aerial photos are images.

 

Creating maps on the fly not only takes a while, but may have variences.

[Grimmy]

Yes. it's zoomed in.I'll look at it today out a little to see if if's closer. I'm kind of disappointed in a way. I wanted this to use for traveling with a little more accuracy.Now..is the streetpilot right on? Do they use internal maps specific to the unit, made to be accurate?

Where is the unit mounted? Where is the antenna? Were you carrying the unit with you when you located the Cashe?

 

The roof of the vehicle really throws off the accuracy if your using the antenna on the GPSr. It cuts off at least half the potential satalites it can use I bet the unit was out from under the roof when you located the Cashe.

 

After getting a mag mount GPS antenna and throwing it up on the roof I rarely see the curser off the road. Without that antenna my GPSV acts the same as you describe. Even with WAAS off it stays put at 300ft range with the external antenna. The suction cup antennas up on the window help but still not as good as geetting the antenna where it can have clear line of site 360degrees.

[+Alan2]

It's mainly the maps. Even if the GPS is on the money to a millimeter. Here's a test I did.

 

I have Garmin's Mapsource in 3 versions. Metroguide, Road and Recreation and Topo and NG Topo. On my computer I create a waypoint in the middle of an intersection using let's say Metroguide. When I switch to Topo, the waypoint is no longer in the intersection but let's say 80 feet off to the northwest. When I switch to Roads and Recreation, the waypoint is off to the east let's say by 60 feet. When I post the coordinates to NG Topo it's off in another direction. This will change depending on what street I do this and in what city. If you have 2 or more maps, try it yourself.

 

The coordinates never changed. It's the maps that change proving that ALL maps are wrong to some degree. Mapmakers have been trying to get it right since mapmaking started. They're getting closer by combining satellite pictures with map drawings, but they still have a way to go.

 

Regarding the cursor arrow, I prefer them being slightly off the road. It makes it easier to see while driving.

 

Alan