Create Polygon from Points

Permanently deleted user

02 Maj 2019 19:52

We have a create point activity, what would be the that equivalent to create a polygon. I have a bunch of points that I would like to turn into a polygon. Any help appreciated.

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  Tom Neer

  02 Maj 2019 19:56

  It's similar, but a little more involved. Since you can create a point. To create a line you just need two or more points. Creating a polygon is a series four or more points where the first and last point are identical.

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  Tom Neer

  02 Maj 2019 19:58

  require([ "esri/geometry/Polygon", ... ], function(Polygon, ... ) { var polygonJson = {"rings":[[[-122.63,45.52],[-122.57,45.53],[-122.52,45.50],[-122.49,45.48], [-122.64,45.49],[-122.63,45.52],[-122.63,45.52]]],"spatialReference":{"wkid":4326 }}; var polygon = new Polygon(polygonJson); ... });

   

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  Tom Neer

  02 Maj 2019 20:00

  Probably better example:

  var singleRingPolygon = new Polygon([[50, 0], [150, 20], [150, -20], [50,0]]);

   

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  Permanently deleted user

  02 Maj 2019 20:28

  Hi Tom, appreciate the help. How would i integrate the above into workflow? Would I use the create value activity?

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  Tom Neer

  02 Maj 2019 20:36

  I guess it would depend on how I received the points. The simplest would be to create the multi-dimension array, the above example, and make sure that the beginning and ending value were identical. Then create the Polygon using the new Polyg([your md array])

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  Ken Lyon

  06 Maj 2019 22:30

  Hi Aaron.

   

  I think you could use Create Value followed by Get Geometry From JSON.

   

  So, for example, if we used the 2D Polygon example from Esri's Geometry objects page, we would set the Expression input of the Create Value activity to be:

  = { "rings" : [[[-97.06138,32.837],[-97.06133,32.836],[-97.06124,32.834],[-97.06127,32.832], [-97.06138,32.837]],[[-97.06326,32.759],[-97.06298,32.755],[-97.06153,32.749], [-97.06326,32.759]]], "spatialReference" : {"wkid" : 4326} }

  Then, we would set the the JSON input of the Get Geometry From JSON activity to be:

  =$value1.result

  (assuming the default id of Create Value is used)

   

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  Permanently deleted user

  08 Maj 2019 13:26

  Hi Ken,

   

  what I ended up doing was using create value to create an array, then created a point, converted to json, used the add item activity to add them to the array

   

  Next step to create the polygon was to use the create value activity with this expression

  ='{"rings": [['+$pointcollection.result+']],"spatialReference": {"wkid":4326}}'

  then get geometry, then create polyon feature

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