OpenStreetMap accuracy

[+NYPaddleCacher]

I am going to be in Costa Rica for a week for business, vacation, and hopefully some geocaching. I've downloaded some basemaps from a routable garmin maps site that cover Costa Rica that I can use on my Garmin. The maps use OpenStreetMap and plan on loading them on my GPSMAP 76Cx before I leave. I'm curious however, how accurate these maps are. I've used a pocket query of costa rica (only 110 caches in the country) and from reading the descriptions about the location of some of the caches the maps appear to be pretty good. They certainly provide much better detail on roads than Google maps (Mapquest maps seem to be much better than Google as well) where I've discovered several roads on the OSM maps that don't show up at all on the Google maps. The Google satellite maps are even worse, as much of the area is low resolution and many parts of the country are obscured by cloud cover.

[+webscouter.]

Never used them in Costa Rica but I did use them in England, Italy, Greece, Bahrain, Japan and South Korea this year. Roads have been really good but sometimes street names are different and the POI are very lacking. For navigation they work great.

[+NYPaddleCacher]

Never used them in Costa Rica but I did use them in England, Italy, Greece, Bahrain, Japan and South Korea this year. Roads have been really good but sometimes street names are different and the POI are very lacking. For navigation they work great.

 

Thanks. I'm mostly interested in using them for navigation since I'll be renting a car and driving from San Jose to a small town on the Atlantic side of the country, then to the Arenal area (sort of in the middle/northwest) to pick up my family (they're taking a shuttle from San Jose while I have business at a small university) the next day, then the following day driving from Fortuna/Arenal to Manuel Antonio on the pacific coast. Some people have recommended getting a GPS with the car rental but as far as I can tell the free OSM routable maps should serve the same purpose. The Costa Rica maps do seem to have quite a few POIs and I've created a PQ with all the geocaches in the country and downloaded a bunch of waymarks as well.

 

The only other thing I can't really tell about the maps is how often they're updated. My trip isn't until near the end of February and don't know if I should bother downloading a net set up maps just prior to the trip.

[+Bear and Ragged]

The only other thing I can't really tell about the maps is how often they're updated. My trip isn't until near the end of February and don't know if I should bother downloading a net set up maps just prior to the trip.

OSM are being added to all the time.

Leave it as late as you can to get the most recent/up to date maps.

[Motorcycle_Mama]

Moving to the GPS and Technology forum.

[+splashy]

You might install a map of your current location on your gps to get used to these maps.

[+HHL]

[…]I'm curious however, how accurate these maps are. […]

 

Moin NYPaddleCacher,

you might have a look inside GSAK’s split screen views (they use OSM maps as well).

Or just compare maps online there:

http://tools.geofabrik.de/mc/?mt0=googlemap&mt1=mapnik&lon=-76.37373&lat=42.58342&zoom=14

 

HTH

Hans

[+NYPaddleCacher]

You might install a map of your current location on your gps to get used to these maps.

 

Not a bad idea. I installed the maps for Costa Rica a couple of days ago played with them a bit. There seemed to be something odd with the zoom levels but current location is also no where near Costa Rica. I usually just use the Garmin Topo maps when I'm in the US and haven't tried routeable maps at all with my GPSr.

[+ecanderson]

I pulled up OSM maps for parts of a variety of Baltic countries for a cruise in August. Fantastic bit of work, even indicating many paths in parks (which given the odd elevations and connections, was really helpful with only a short time to score a cache). I found the OSM community in Europe to be almost OCD when it comes to detail in their map submissions.

 

Being cheap, and needing full maps for the Caribbean islands south of Puerto Rico and on down to S. America for only a day per island, I loaded up a set of OSM for them before going on vacation. For those maps, I found some peculiar things that I hadn't expected after my good European experience. In particular - on Aruba, I noted a number of roads that we traversed were almost but not quite complete on the map. We'd be cruising down what appeared to be a dead-end road that the map said would stop short of a main highway by 0.2 mile or so, only to find that it really did connect as one would have expected. It was as though someone were submitting a track they'd made of the road and were losing the last segment or something.

 

How it will be in Costa Rica is something I can't answer. I can only say that the quality in a given area is strictly a function of the effort that the local community is putting into the project.

 

One suggestion based upon my experience -- go ahead and load up Costa Rica and look to see if there are "stranded" road segments in the map of the sort I was seeing in Aruba. If you see a bunch of those, you're going to have to make some assumptions when navigating.

[+splashy]

Being on a cruise gives you a map on the Today shipspaper and when leaving the ship you always find local maps, these maps with the OSM should be enough for the day on shore.

Edited January 4, 2011 by splashy

[+ecanderson]

Being on a cruise gives you a map on the Today shipspaper and when leaving the ship you always find local maps, these maps with the OSM should be enough for the day on shore.

The maps in the ship's daily give you only a huge overview of the country/area (no street detail at all) and detailed maps only of the immediate port area (for stopping by their "partner" shops, of course). Maps proffered by the locals as you depart the ship are also usually very shopping oriented, providing only information close-in to the port. I find that many caches are not near the port, and the OSM is often my only source for navigation.

 

OK - cache addict - I actually select any ship sponsored shore excursions based upon the detailed "stop" information in the shorex brochure, comparing the sites they describe to potential cache sites. There again, we're often out in the boonies of the island/country we're in, and again, having the OSM maps handy makes the necessary wandering away from the group quicker and easier to recover from when the cache is bagged.

 

Again, I can't say enough good things about the effort the OSM community has made in Europe. In Germany, one might even argue that there's too MUCH detail!

[+splashy]

The overview maps together with the OSM should be ok

The island maps usually have the major road on them.

[+Woodstramp]

ecanderson said:

 

".... I found some peculiar things that I hadn't expected after my good European experience. In particular - on Aruba, I noted a number of roads that we traversed were almost but not quite complete on the map. We'd be cruising down what appeared to be a dead-end road that the map said would stop short of a main highway by 0.2 mile or so, only to find that it really did connect as one would have expected. It was as though someone were submitting a track they'd made of the road and were losing the last segment or something."

 

That may explain some wierd routing troubles I had a while back when trying the local (Alabama) OSM maps on a 60csx. About half the time the OSM maps provided really good autoroutes on that unit. Often better than my Nuvi with CN. But, sometimes the GPS would crank out some really strange (overly long) route plans. One test route from my hometown to my father-in-laws in particular....normally a 5 mile route. The OSM/60csx combo would route a 20 mile loop averting a highway bridge over the river. It was like there were hidden obstacles and the 60 was doing a detour. This happened a good bit, even in places where there was no obvious breaks in the OSM roads.

[nhfours]

That may explain some wierd routing troubles I had a while back when trying the local (Alabama) OSM maps on a 60csx. About half the time the OSM maps provided really good autoroutes on that unit. Often better than my Nuvi with CN. But, sometimes the GPS would crank out some really strange (overly long) route plans. One test route from my hometown to my father-in-laws in particular....normally a 5 mile route. The OSM/60csx combo would route a 20 mile loop averting a highway bridge over the river. It was like there were hidden obstacles and the 60 was doing a detour. This happened a good bit, even in places where there was no obvious breaks in the OSM roads.

Almost exactly my experience in New Hampshire (and on a trip to Boston). Since I contribute (in a small way) to the mapmaking I posted a query on their forum: Strange (buggy) routing with routable map. It seems that the web site, YourNavigation.org, which uses OSM data, routes correctly, while my MapSource, whether on my computer or on my GPSr, gives weird routes.

 

Since my original post I have observed several other cases of what seems like avoidence of a specific segment of a highway. Looking at the OSM data (I can edit it) does not seem to reveal anything.

 

Is anyone getting consistently good routes from OSM in the US? OSM is far more advanced in Europe than on these shores.

[seldom_sn]

ecanderson said:

 

".... I found some peculiar things that I hadn't expected after my good European experience. In particular - on Aruba, I noted a number of roads that we traversed were almost but not quite complete on the map. We'd be cruising down what appeared to be a dead-end road that the map said would stop short of a main highway by 0.2 mile or so, only to find that it really did connect as one would have expected. It was as though someone were submitting a track they'd made of the road and were losing the last segment or something."

 

That may explain some wierd routing troubles I had a while back when trying the local (Alabama) OSM maps on a 60csx. About half the time the OSM maps provided really good autoroutes on that unit. Often better than my Nuvi with CN. But, sometimes the GPS would crank out some really strange (overly long) route plans. One test route from my hometown to my father-in-laws in particular....normally a 5 mile route. The OSM/60csx combo would route a 20 mile loop averting a highway bridge over the river. It was like there were hidden obstacles and the 60 was doing a detour. This happened a good bit, even in places where there was no obvious breaks in the OSM roads.

 

There was probably a gap or unconnected node somewhere on the route. The US maps are generated from Census Bureau Tiger shapefiles, and unless someone has edited them thoroughly, this sort of error gets through. The only way to test for it is rigorous use of route continuity tools in the map author's editor and the US has lots of roads to check. Woodstramp should join OSM, find the errors in his area, and update the map. Then the next time he updates his map will route better.

 

One other thing, where are you getting your maps? There are a number of OSM sites out there. This is probably the best: http://garmin.openstreetmap.nl

Edited May 8, 2011 by seldom_sn

[+ecanderson]

One other thing, where are you getting your maps? There are a number of OSM sites out there. This is probably the best: http://garmin.openstreetmap.nl

Why would it make a difference which server you use to get the maps? I've never found any difference between the servers (apart from the fact that one is often faster than the other to produce the results).

[+Woodstramp]

 

One other thing, where are you getting your maps? There are a number of OSM sites out there. This is probably the best: http://garmin.openstreetmap.nl

 

That is the site where I'd originally tried the OSM maps. I only downloaded them to see how well my (then newly purchased) 60csx would route. I was pleased with the 60's performance and dumped the OSM stuff and got City Navigator.

 

I'd join the forum there, but seeing how I now longer have that certain mapset for ID (to alert the author). I could give coordinates for the problem area I mentioned if that would help. The map would not allow routes over this bridge on the Coosa River in central Alabama. N 33 31.309' W 86 13.563'

Edited May 9, 2011 by Woodstramp

[seldom_sn]

One other thing, where are you getting your maps? There are a number of OSM sites out there. This is probably the best: http://garmin.openstreetmap.nl

Why would it make a difference which server you use to get the maps? I've never found any difference between the servers (apart from the fact that one is often faster than the other to produce the results).

 

I'm not familiar with all the servers, but I know some don't provide complete map installers. It's reasonable to assume that they may be using different (less reliable) versions of the compiler or different scripts.

[seldom_sn]

 

One other thing, where are you getting your maps? There are a number of OSM sites out there. This is probably the best: http://garmin.openstreetmap.nl

 

That is the site where I'd originally tried the OSM maps. I only downloaded them to see how well my (then newly purchased) 60csx would route. I was pleased with the 60's performance and dumped the OSM stuff and got City Navigator.

 

I'd join the forum there, but seeing how I now longer have that certain mapset for ID (to alert the author). I could give coordinates for the problem area I mentioned if that would help. The map would not allow routes over this bridge on the Coosa River in central Alabama. N 33 31.309' W 86 13.563'

 

OSM gives lat/lon in decimal degrees, not degrees and minutes, but I assume you are talking about the bridge where SR24 crosses the Coosa river. If so, there were two nodes where Noah Drive and an unnamed road connected to SR34 that were probably too close for a Garmin to route over (distance is about 6 feet). I spread them maybe 12' apart. Try it out in a week or two after the guys with the compiler have updated their data.