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Anonymous · #1 (**permalink**) 04-30-2004

Hi,

I'm currently developping an application using MapPoint 2004 and I want to optimize the stopplaces for a route. Unfortunaltely it takes already 5 minutes to optimize 5 stops!? Is there anyway to speed up this process? Maybe a parameter to only take highways?

Further i'm trying to implement some geofencing. I want to check if a given location is within a random drawn shape (polyline or circle for example) Is there any way of doing this? A cirkel is not so diffucult but a free hand drawn image seems almost impossible.

I'm programming in C# so if you have some example's I would be very grateful.

Thanks

**Winwaed** · #2 (**permalink**) 04-30-2004

Optimising is slow because of all the different routes it tries to find. I suspect (but haven't done any explicit tests) that it takes longer if the waypoints are spread over a wide area.
One idea I had for speeding this up, was to sort them by "as the crow flies" distances between locations or zipcodes.
The problem with this is that a distance might appear close but the driving distance is much longer due to a lack of decent roads (eg. across a narrow lake or mountain range).
The classic UK example would be Ayr to the tip of the Mull of Kintyre. Takes quite a few hours because you have to go well north of Glasgow and then back down again! Alaska probably has similarly extreme examples (eg. Haines to Skagway).

For finding if a point is in a polygon: I've coded this before. I think I took my basic algorithm from Sedgwick's "Algorithms" but it is probably covered elsewhere (eg. Graphics Gems).
Basically, you create a 'ray' from your point to infinity in one direction (typically in the +X direction, constant Y). You then count the number of times this ray crosses the polygon boundary. If it is even, then you're outside the polygon. If it is odd, then you're inside it.

There are some gotchas to watch out for like a polygon corner having the same Y value as the point, or a polygon edge lying exactly on the ray. Also you're working on a sphere which complicates things a little.

Richard
PS: I could be contracted to code this up for you

thejun · #3 (**permalink**) 05-13-2004

so you can create a geofence by drawing it...
does it auto create latitude and longitude?

couldnt you do a search for a point by finding out if its outside that latitude and longitude, or would that not work for a polygon?

I do not quite understand the even and odd result.

If you had multiple geofences that overlap eachother, how would you find out all the geofences that point resides in?

**Winwaed** · #4 (**permalink**) 05-13-2004

If the polygons overlapped, you could check the point against each polygon in turn. Yes this could be slow, depending on the complexity and number of polygons. It can be greatly speeded up by comparing against the polygon's rectangular extents, and/or by sorting polygons.

re. the odd/even bit: Try it on a piece of paper. Draw a polygon. Start with a simple one like a square.
Point outside square:
- If ray misses square => 0 intersections
- If ray passes through square => 2 intersections
Point inside square:
- Ray always has one intersection

Try more complicated polygons with concave faces/etc, and you'll find an odd number of intersections occur when the point is inside the polygon.

Richard

thejun · #5 (**permalink**) 05-13-2004

so i really only need to do 1 ray check then. if it comes back with odd, then its inside, if 0 or even, its outside. That should speed up the check.

**Winwaed** · #6 (**permalink**) 05-14-2004

You need one ray check for each point that you test in each polygon.

Richard

Anonymous · #7 (**permalink**) 05-17-2004

Is it possible to get the lat/lon of a polygon that the users has drawn on the map?

**Eric Frost** · #8 (**permalink**) 05-17-2004

It is.. you can loop through the nodes. There is some code in this example: http://www.mp2kmag.com/importersub01.asp

Eric

Anonymous · #9 (**permalink**) 05-17-2004

Hu, that last artical is not what I'm searching. It's about MapInfoFiles??? Through which nodes can I loop?

BTW I'm using C#

Anonymous · #10 (**permalink**) 05-17-2004

Found it, kinda shitty way to get the locations in C# from a polyline.

Code:

foreach(MapPoint.Shape s in ActiveMap.Shapes)
			{
				if(s.Name == "")
				{
					System.Array k = (System.Array)(s.Vertices);  
					System.Collections.IEnumerator r =  k.GetEnumerator();
					for(int i = 0; i < k.Length;i++)
					{
						r.MoveNext();
						MapPoint.Location l = (MapPoint.Location)(r.Current);   
						ActiveMap.AddPushpin(l,"test");
					}
				}
			}

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Speed up optimize for routes + geofencing

Speed up optimize for routes + geofencing

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Speed up optimize for routes + geofencing

Speed up optimize for routes + geofencing

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