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google-mapspolygonpolyline

Why does the width of a polyline buffered with JSTS vary with latitude?

I have one simple question. I wanted to draw a google.maps.Polygon around google.maps.Polyline. I implemented it by mixing solutions mentioned in How to draw a polygon around a polyline in JavaScript? . My question is about the wideness of the buffer. If u look at the example in https://coderwall.com/p/zb_zdw/buffered-polyline you can see that the buffer is wider when the polyline is horizontal. When the line is vertical buffer is smaller. Why is that? Is that correct? Example from my program: https://ibb.co/i2m2BF

Solution

  • The width of the polygon is set in degrees. From the code:

    var distance = 10 / 111.12, // Roughly 10km)

    The length of a degree of longitude varies with latitude.