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Topic: Speed zone data in easily converted format (Read 872 times) previous topic - next topic

J.C. Woltz

would GIS or other databases be available?

CrossRoads

Garmin sells databases with the information you are looking for.  I just paid $99 I think for lifetime updates for my Garmin Nuvi 205.
You can buy the same database and pick out the info you need including speed limit by road section (I've the displayed speed limit change as the sign on the side of the road goes by.
Its like a 16MB compressed file you download, then it uncompresses for loading into the Nuvi.
I don't know if anyone maintains that as publicly available data.
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

robtillaart

Not checked if it contains speed limit info but wortha look or two - http://www.openstreetmap.org/ - They use color info to differentiate between road-types - that's a first order speed indication imho, so it should get you started. As it is an open project I think you can use their database, check the license to be sure.

Then you could overlay the roadmaps with squares (triangles, circles?) with the same speedlimit.  So you need a table to map squareID to longitude/latitude points and speedlimit:

{SquareID, x1,y1,x2,y2, speed}*

You need to sort this table on both {x1, y1} and use binary search ;


Succes,
Rob
Rob Tillaart

Nederlandse sectie - http://arduino.cc/forum/index.php/board,77.0.html -
(Please do not PM for private consultancy)

robtillaart

@CrossRoads,

can you read the data when it is uncompressed? I expect the data is encrypted /cloaked somehow so finding the speedlimits needs additional work but I expect that reverse engineering is probably not allowed.
Rob Tillaart

Nederlandse sectie - http://arduino.cc/forum/index.php/board,77.0.html -
(Please do not PM for private consultancy)

CrossRoads

I never tried looking at it.
It appears to be a file called npGarmin.dll.
Opening with Notepadd++ doesn't do much for me:

That's why I suggest you talk to Garmin see if they will sell you a database of what you want.
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

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