topic Re: Buffer Geometry of a Dropdown Selection in ArcGIS JavaScript Maps SDK Questions

Buffer Geometry of a Dropdown Selection

ClintonLunn — Sat, 11 Dec 2021 09:20:58 GMT

Hello all,

I am trying to buffer a polygon of a dropdown selection. I am hoping somebody can point me where I am going wrong.

var TRSSelect = dom.byId("selectTownshipPanel");

on(TRSSelect, "input", function(e) {
  var type =  e.target.value;

  var task = new QueryTask({
    url: panelurl + "2"
  });

  var params = new Query({
    where: "trs = '" + type + "'",
    returnGeometry: true
  });
  task.execute(params)
  .then(function(response) {
    console.log(response.features["0"].geometry);
    console.log(response.features[0].geometry);
    console.log(response.features[0].geometry + " TRS response FEATURES");
    console.log(response.features["0"].geometry + " TRS response FEATURES");

    buffer = geometryEngine.geodesicBuffer(response.features["0"].geometry, 100, "feet", false);
    
    console.log(typeof buffer);
    console.log("buffer completed");
    bufferLayer.add(new Graphic({
      geometry: buffer,
      symbol: polySym
    }));
    
  });
});‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

My output for this code is:

It is able to retrieve the geometry, but will not execute the buffer (does not lot to console "buffer completed") and add to the graphic layer.

I have isolated this to the buffer because if I pass in the response.features[0].geometry, the resulting geometry can be added to my graphic layer illustrated here:

    //buffer = geometryEngine.GeodesicBuffer(response.features["0"].geometry, 100, "feet", false);
    
    console.log(typeof buffer);
    console.log("buffer completed");
    bufferLayer.add(new Graphic({
      geometry: response.features[0].geometry,
      symbol: polySym
    }));
    
  });
});‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Graphic layer is displayed now when passing in just geometry of response features:

Re: Buffer Geometry of a Dropdown Selection

JohnGrayson — Thu, 01 Mar 2018 18:41:41 GMT

...check the spelling of the geometryEngine method... geometryEngine.geodesicBuffer

Re: Buffer Geometry of a Dropdown Selection

ClintonLunn — Thu, 01 Mar 2018 18:47:01 GMT

John,

While I do feel very silly for that little typo, that did not make it work. I will update the code in my question to reflect that correction. Thank you!

Re: Buffer Geometry of a Dropdown Selection

KenBuja — Thu, 01 Mar 2018 18:54:36 GMT

What is the spatial reference of the geometry you're attempting to buffer? Is it WGS-84 or Web Mercator? If not, you'll have to use the GeometryService buffer method.

Re: Buffer Geometry of a Dropdown Selection

ClintonLunn — Thu, 01 Mar 2018 19:20:40 GMT

Ken, the spatial reference is listed as:

Spatial Reference: 102113 (3785)

This seems as though it is a deprecated form of Web Mercator?

Re: Buffer Geometry of a Dropdown Selection

KenBuja — Thu, 01 Mar 2018 19:30:06 GMT

Yes, according to this post from Melita Kennedy‌, Esri's guru on projections and spatial references. Although, according to the isWebMercator method, 102113 would return True.

Re: Buffer Geometry of a Dropdown Selection

ClintonLunn — Thu, 01 Mar 2018 19:36:22 GMT

Ken,

Forgive my ignorance, but does this deprecated spatial reference now mean that the geometryEngine will not work in this case?

In which case, I'd either have to use the GeometryService or change my layer to conform to this spatial reference requirement, correct?

Thank you,

Clinton

Re: Buffer Geometry of a Dropdown Selection

KenBuja — Thu, 01 Mar 2018 19:38:16 GMT

I don't know, unfortunately.

Is the wkid 3785 correct? That comes up as something else: Popular Visualisation CRS / Mercator: EPSG Projection -- Spatial Reference

Re: Buffer Geometry of a Dropdown Selection

ClintonLunn — Thu, 01 Mar 2018 19:41:20 GMT

Yes, that is correct. I was puzzled when I searched that wkid too.

Re: Buffer Geometry of a Dropdown Selection

MelitaKennedy — Fri, 02 Mar 2018 00:36:36 GMT

It's very old. My records show both 102113 (3785) / 102100 (3857) as being added at 9.3.0, but I think that's wrong and 102100 was added at 9.3.1. Anyway, the switch to 102100 / 3857 occurred a lot of releases ago. EPSG:3857 was added by EPSG in 2008.

Other software often can't use the Esri or EPSG definition of 102100 / 3857 because they both use a variant of the "Mercator" map projection. So a software that has the regular Mercator might use EPSG:3785 which uses a sphere-based GCS instead to force the usage of a major auxiliary sphere (radius = semimajor axis).

The functions might be failing because the input/output GCS are actually different. There is a transformation, 15973, which converts between the two GCS.

Re: Buffer Geometry of a Dropdown Selection

ClintonLunn — Tue, 13 Mar 2018 15:45:12 GMT

I wanted to post an update to this. The function was failing because of differing GCS. After changing this, all is well and I was able to buffer.