topic Re: WebMercator to Geographic and back gives a different point in ArcGIS JavaScript Maps SDK Questions

WebMercator to Geographic and back gives a different point

AmarG1 — Thu, 03 Dec 2020 22:32:51 GMT

Hi,

Using WebMercatorUtils to convert a point from webmercator to geographic and then back to webmercator doesn't give the original value back. Any ideas why?

point1: {x: -27763769.230105422, y: -6212655.210572942}

webMercatorUtils.webMercatorToGeographic() on point1 returns point2

point2: {x: 110.5938175582902, y: -48.63203914410154}

webMercatorUtils.geographicToWebMercator() on point2 returns point3

point3: {x: 12311247.455472855, y: -6212655.210572806}

I was hoping point1 and point3 to be same but that doesn't seem to be the case.

Thanks!

Re: WebMercator to Geographic and back gives a different point

DanPatterson — Thu, 03 Dec 2020 22:43:29 GMT

same datum for the geographic? There are many GCS's

Re: WebMercator to Geographic and back gives a different point

AmarG1 — Fri, 04 Dec 2020 16:08:16 GMT

Hi Dan,

I tried this instead:

point1 = {"spatialReference":{"wkid":3857},"x":-27763769.230105422,"y":-6212655.210572942}

let point2 = webMercatorUtils.project(point1, { wkid: 4326 });

point2 : {"spatialReference":{"wkid":4326},"x":110.5938175582902,"y":-48.63203914410154}

let point3 = webMercatorUtils.project(point2, { wkid: 3857 });

point3: {"spatialReference":{"latestWkid":3857,"wkid":102100},"x":12311247.455472855,"y":-6212655.210572806}

Does that address datum?

Thanks!

Re: WebMercator to Geographic and back gives a different point

DanPatterson — Fri, 04 Dec 2020 16:54:39 GMT

That isn't due to a datum difference assuming your long/lat values are correct

You can confirm using an online calculator

Re: WebMercator to Geographic and back gives a different point

AmarG1 — Fri, 04 Dec 2020 20:44:17 GMT

I'm getting the same response from https://tool-online.com/en/coordinate-converter.php#

-Thanks

Re: WebMercator to Geographic and back gives a different point

DanPatterson — Fri, 04 Dec 2020 22:21:50 GMT

here are the images for various combinations from there.

so assuming this is correct... and you have checked your inputs