MapForums

Gilles Kohl submitted this update to his previous article on reverse geocoding

Read the full article: http://www.mp2kmag.com/articles.asp?ArticleID=47

For some time I've tried to find a way to find the coordinates of the staring point of route segments. I want to be able to sent these coordinates to my basic garmin GPS. I've written code that sends the points of a polyline to my GPS. But I always have to trace a route by hand because MapPoint only returns the middle of a route segment and not the start. Your article gave me hope by using the extrapolation technique I thought I would be able to find the starting points of all the route segments. This works for strait route segments, but for example on a roundabout this doesn't work anymore. There the middle of the route isn't in the middle of the start and end of the segment. While exploring this technique I came up with a completely different solution. I found out that when you select a route segment, a label with the instruction appears on the map at the start of the segment. I found out that by using the GetPixel or, better the GetBitmapBits, api calls I could analyze the map bitmap and find the location of this label and therefore the starting point of a route segment. There are many disadvantages to this technique. It is slow and the different maps are 'flashing' over the screen. Also I have to improve the technique further because it is not working 100%. But if there are others who are interested in this technique I'd be happy to share it, and maybe together we can further improve it.

Nico Bontenbal
The Netherlands

If you would like to submit it as an article, that would be the most effective way to get feedback on the technique.

Eric

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