Union Polygons

[Diogo Outerelo da Silva]

Hello,

I have some days trying to make a "bound" to my polyline route but i still having problem. First i tried to use the route boxer like the google example (http://gmaps-samples-v3.googlecode.com/svn/trunk/routeboxer/routeboxer-v3.html) demo gallery, but with a large route and a great precision its make the browser stop, because make so many latlongbounds. So i was searching for another solution and i found from Marcelo Montagna here (http://gis5.com/pois_along_route/gm_pois_along_route.php), but its protected to copy. Then i start make my own code... 

There is the step that i think to my code:

1 - Make a circle around each point(lat, long) - like 12 points around each the latlong

2 - Get the most external point for each 2 latlong circle and make a polygon (fecho) - total = (points - 1) poligons

3 - union the poligons to make a unique polygon and apply a color and opacity

the problem is that i can`t find a algorithm to "union" this polygons. Someone know a algorithm that i can use or a API for google maps to make it with the polygons?

I can`t make another polyline with biggest stroke weight because i need the "bound" points to search for POI`s.

Thx in advance

-- 

,
Diogo

--

[geoco...@gmail.com]

On Feb 11, 7:19 pm, Diogo Outerelo da Silva <diogoouter...@gmail.com>
wrote:

> Hello,
> I have some days trying to make a "bound" to my polyline route but i still
> having problem. First i tried to use the route boxer like the google example

> (http://gmaps-samples-v3.googlecode.com/svn/trunk/routeboxer/routeboxe...)

> demo gallery, but with a large route and a great precision its make the
> browser stop, because make so many latlongbounds. So i was searching for
> another solution and i found from Marcelo Montagna here (http://gis5.com/pois_along_route/gm_pois_along_route.php), but its protected
> to copy. Then i start make my own code...
> There is the step that i think to my code:
>
> 1 - Make a circle around each point(lat, long) - like 12 points around each
> the latlong
> 2 - Get the most external point for each 2 latlong circle and make a polygon
> (fecho) - total = (points - 1) poligons
> 3 - union the poligons to make a unique polygon and apply a color and
> opacity
>
> the problem is that i can`t find a algorithm to "union" this polygons.
> Someone know a algorithm that i can use or a API for google maps to make it
> with the polygons?

You could do a convex hull of all the vertices.

-- Larry

[Diogo Outerelo da Silva]

i use convex hull to get the external points of each polygon. the problem is to union the polygons. if i use  the convex hull in all points i will not get a right route.

The image1 of the attach is what i will get if i do the convex hull with all points. The image2 is what i am doing in the code. I need to union/merge the polygons.

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--
Atc,
Diogo

--

[Rossko]

> The image1 of the attach is what i will get if i do the convex hull with all
> points. The image2 is what i am doing in the code. I need to union/merge the
> polygons.

I see the problem, it will be quite a challenge to get a single
polygon as you want. Do you think the performance will be any better
than with routeboxer?

I think there is a method to generate a "thick polyline", by
calculating the bearing from each vertex to the next, and setting out
points at a perpendicular distance either side.

[Esa]

Bill Chadwick's demo page is a great resource for this kind of
problem.
http://www.bdcc.co.uk/Gmaps/BdccGmapBits.htm
See the bottom of the page. Distance to Polyline and Parallel
Polylines.

The syntax is for API v2 though.

[Diogo Outerelo da Silva]

Hello,

   @Rossko

        Thx for answer

        Router boxer with a precision of 500 meters and a route with 3000km in diagonal make more than 1000 bounds. 

       

   @Esa 

        Thx for answer

        I saw the example, but i needed a polygon to draw on map. With the polygon i can calcule if a latlong is in the route. 

        

After i search more i found a API called JTS, for java. This API have the convex hull algorithm, that i already had, and the union of polygons. Now i am using this API to calculate the polygon and return to draw on client( image in attach).

Thx for help guys

,

Diogo