topic Re: SRID for WS84 Web mercator aux sphere? in Data Management Questions

SRID for WS84 Web mercator aux sphere?

JamiePortolese — Mon, 13 Feb 2017 13:52:45 GMT

Hi,

I've received some ESRI biz data in CSV format and I'm trying to create a SQL Server spatial layer with it before I query it down to more manageable datasets. The CSV file contains lat long coordinates that are in WGS 84 Web Mercator Auxilary Sphere. I want to import the data into sql and create a geometry field with the coordinates but can't seem to find any reference to the SRID I would use to convert the lat long to geometry.

I eventually want the data to land in SRID 4326 . Do I even need to reproject it? What SRID should I use to bring it into SQL Server geometry?

thanks in advance

Jamie

Re: SRID for WS84 Web mercator aux sphere?

AdamZiegler1 — Mon, 13 Feb 2017 14:31:01 GMT

Hi Jamie - WGS 84 Web Mercator Auxilary Sphere SRID is 3857. Since 4326 is geographic and 3857 is projected a reprojection would be necessary.

-Adam Z

Re: SRID for WS84 Web mercator aux sphere?

NeilAyres — Mon, 13 Feb 2017 14:40:53 GMT

The above info from aziegler is spot on.

But are you sure your input csv is actually Web Merc coords. Sounds very unusual.

What do those numbers look like?

And extra unwanted info, both 3857 and 4326 (GCS_WGS_1984) are WGS84 based, a projection is necessary but no transformation is needed.

Re: SRID for WS84 Web mercator aux sphere?

NeilAyres — Mon, 13 Feb 2017 14:42:56 GMT

If the coordinates are Lat/Long, again, what do those numbers look like??

"lat long coordinates that are in WGS 84 Web Mercator "

If they are Lat/Long, then they are not Web Merc but are already GCS_WGS84 (4326)

Re: SRID for WS84 Web mercator aux sphere?

JamiePortolese — Mon, 13 Feb 2017 18:06:52 GMT

Using that as the SRID to create a geometry field, when I add the table to arcmap, it places the points in meters and not decimal degrees like I would expect. Perhaps I'm not understanding things. If I'm given lat long values are the values specific to the web Mercator auxiliary sphere projection or should they be imported as geographic? I'm having a hell of a time trying to line things up with my other data that's already in Geographic wgs84 SRID 4326.

Re: SRID for WS84 Web mercator aux sphere?

JamiePortolese — Mon, 13 Feb 2017 18:09:21 GMT

The coordinates are (for example) -97 longitude, 26 latitude (they are from Texas). I think this points to my misunderstanding of Lat Long coordinates in general. I normally work in projected coordinate systems and only recently started doing a lot with lat long values.

Re: SRID for WS84 Web mercator aux sphere?

AdamZiegler1 — Mon, 13 Feb 2017 18:14:01 GMT

Hi Jamie - I think GSCUser85‌ was hitting this right earlier. Those are geographic coordinates. It would appear that your data is already in WGS 84, i.e. SRID 4326.

-Adam Z