Thread: need info mappoint/gps/vb6 developement

Originally Posted by CorollaVerso'04

i have created an app. in vb6 with mappoint control for car navigation
i read the com port on which the gps antenne sets its data.
the user can type in a destionation location and the gps location is used as start location. if show the first element of the directions collection to the user (driver). after 2 seconds i do a complete recalc whereby is set the start location to the new gps location. again i show the first element of the directions collection to the user.

this can't be the right way to go (cause for e.g. what if 2 or more directions are needed within the 2 seconds refresh rate i use)

but i can't figure out how to go if i keep the start location fixed.
Q: how to go on with the gps location and the directions. what direction element has to be shown?
Q: what if the driver is lostand far off-track? how do the 'fixed' set of directions help in any way?

Can anyone point me out how the program flow goes?
Do i have to recalc over and over?
How do i know of an refresh/recalc is needed during runtime?
Don't need exact coding bus samples are always welcome.

Greetings
and a merry x-mas from holland

You should only need to recalculate if you've gone off track, then it recalculates from where you are!

MapPoint for Navigation? I said it many times, don't bother!

uhmmm.... wrong forum to post?

I think the issue is how to detect if you've gone off track? I assume this is done by getting a location object for your current position and comparing the details of that location with the items in the directions collection. I'm not sure how to do this specifically but haven't studied the problem at length either. If recalculation is fast enough, perhaps you can just compare the top items from the original directions collection with your newly computed route. If they differ then either you've gone off route or you've already completed the first instruction.

Originally Posted by mpattonm

uhmmm.... wrong forum to post?

really

@CorollaVerso'04

but I agree with rando ... once you select a destination you would calculate all the directions required to get to that destination from your start point. The only time you would need to calculate is when you go off track in which case you would need to recalculate a new set of directions to the destination.

Your 2 seconds refresh should be fine, a possible work around would be to identify the average speed and if there happens to be 2 (or more, though unlikely) directions within that time period just display them next to one another.

Originally Posted by OdysseyPC

really

It was moved after his comment.

@frodo: did i post in the wrong forum???

Mappoint can be used for real-time navigation very effectively, however, it does have some major limitations that have to be overcome if you want to compete with something like destinator that was built just for real-time nav. Specifically theres the issues that you have already run into like how do you get directions and know which part of the route the GPS is on so you can show that direction. This can be easily accomplished by using the DistanceTo method from your current location to the Direction object your currently on, starting at 1 and incrementing everytime you say get within .1 miles of it until you reach the destination. For automatic route recalculation, the only way that I have found to do it well is to do visual analysis of the map for the route. If the current GPS location is far away from any part of the blue or green highlighted route, it must mean you have gone off course so you must recalculate. I use the copy method to get the bitmap data to do this and post process it alot to get it to a form I use for analysis.

Once you get these features working your still going to have to jump through a lot more hoops to get the SDK to do what you want. The most pressing of which, I think, is autorotation, which can be done, but is very CPU intensive since your rotating bitmap data not vector data and I've only been able to do it well by using Direct3D and taking advantage of 3D hardware which can yeild frame rates well in access of 100 fps while rotating versus maybe 15 fps you'll get otherwise. Another problem is recalculating routes on a highway or other limited access road since any starting location that starts on a highway will be automatically moved to the nearest non-limited access road, it means any route you calculate or recalculate while driving on a highway won't start where it should. The maps in mappoint are also not very good for use in the car since they are low contrast so I have found recoloring the roads is a must. All these limitations can be overcome, however, you will have to step outside of the SDK to do all of this and probably outside of VB to a lower level language. I used C++ for everything.

Thanks a lot for your reaction. This was the kind of input I was looking for.
A few questions on your reaction came up:
1. has Destinator got european maps (Belgium / Netherlands / Luxemburg / Germany)?
2. Autorotation is something I don't bother much, I search trough the second direction element for words like: left,right(etc),bear,first(etc),roundabout and show a picture I have drawn for that.
3. @"recalculating routes on a highway.." what is meant by: "(non-)limited access roads". It might sound dumb but i havent got much of a clue...and english isn't my native language at all. Is it "Limited" like limited for distinct user groups say like bicycles etc.?
Thanks!

Originally Posted by CorollaVerso'04

3. @"recalculating routes on a highway.." what is meant by: "(non-)limited access roads". It might sound dumb but i havent got much of a clue...and english isn't my native language at all. Is it "Limited" like limited for distinct user groups say like bicycles etc.?
Thanks!

In this case, a highway = limited access road. Limited access means specialized on-ramps and exits, no crossroads except as a briged overpass or underpass and no traffic lights. Think Autobahn.