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Smoothing out multi-polygon shape

#1

Hello,

We are creating a wind swath for a tropical storm/hurricane on the map. We use the lat/lons of the wind edge, which results in a polygon for each forecast hour.

We create the map shape by using multiple polygons via

POLYGON((x y,x y, x y),(x y,x y, x y),(x y,x y, x y))

where each (x y,…) is a forecast hour’s polygon.

Hopefully, this will create a smooth looking shape. However, if the storm is moving very fast, there are gaps in the wind swath, as can be seen on the attached screen capture.

Is there a way to smooth out the resulting shape? I have tried Get Outer Ring, but if the storm turns during the forecast, the entire area between the first and last forecast hours get filled in. We need it to smooth out from hour to hour (polygon to polygon).

Any ideas?

Thanks,
Dib

polygons.png1733×963 187 KB

#2

Hi Dib,

I think we don’t have an existing API can help you generate a smoothing edge by all the polygons.

I am not sure how is the data format to describe a storm(maybe we can describe is like a ellipse), but I think if you know the shape for each hours, you can generate a new shape which contains the key vertexes for each hour. That means you draw two shapes on map anytime, one is the newest storm shape, the other is generated shape for all past hours.

If I misunderstand anything please let me know.

Regards,

Don

#3

Thanks Don. I ended up creating a polyshape from one hour and the next hour’s worth of data, then getting the OuterRing of that, and adding it as an internal feature, It’s a tiny bit more memory and processor intensive, but it helped with the smoothing, especially at the more zoomed-out levels.

#4

Hi Dib,

Very glad to hear it’s helpful.

Thanks,
Peter