topic Re: ESRI imagery word 2D not projecting on the fly in Coordinate Reference Systems Questions

ESRI imagery world 2D not projecting on the fly

Oliver_Burdekin — Thu, 17 Nov 2016 10:48:37 GMT

I have traced the outline of an area in Google Earth. Having saved the KMZ I've converted it to a shapefile and then reprojected the shapefile to Arc 1950 UTM 35s (using transformation 8). My data frame is in Arc 1950 UTM 35s. In the dataframe properties I have set a transformation to WGS84 (using transformation 8).

When I add the basemap "World Imagery" (which comes in Web Mercator Auxillary Sphere projection) everything is fine. See below:

However, if I choose the "ESRI Imagery World 2D" basemap (which comes in WGS84 projection) the shapefile and the basemap no longer line up. See below:

Why is this?

**Update**

As a further test I have started a new MXD. I've brought in the ESRI 2D basemap which has set the dataframe CRS to EPSG 4326 (WGS84).

I've then created a new shapefile in WGS84 and traced around the same feature:

I've converted this new shapefile to a KMZ and this is what it looks like in Google Earth:

Again the offset is ~70m.

Re: ESRI imagery word 2D not projecting on the fly

JayantaPoddar — Thu, 17 Nov 2016 11:28:02 GMT

Make sure you are using the appropriate Geographic Transformation method.

Refer <ArcGIS Install Directory>\Documentation\geographic_transformations.pdf

Re: ESRI imagery word 2D not projecting on the fly

Oliver_Burdekin — Thu, 17 Nov 2016 12:10:15 GMT

Yes, the AOI is in Zambia. I've also double checked my existing shp (in Arc1950 UTM 35S) by projecting back to WGS 84 UTM 35S (using transformation 😎 and then downloading Sentinel 2 satellite data for the area. The sentinel 2 data comes in WGS 84 UTM 35S and so I started a new map, added the sentinel data then added the reprojected (WGS83 UTM 35s) shapefile. This all lines up. See below:

And the ESRI Imagery World 2D again (with the same data overlaid):

Re: ESRI imagery word 2D not projecting on the fly

NeilAyres — Thu, 17 Nov 2016 12:50:59 GMT

What's the distance of that offset?

Have you just compared the 2 image datasets? Perhaps the referencing on one is a bit off.

Re: ESRI imagery word 2D not projecting on the fly

Oliver_Burdekin — Thu, 17 Nov 2016 12:55:28 GMT

The distance of the offset is approximately 70m. The two image files (being the Sentinel data and the ESRI 2D imagery) are also offset by the same distance. Bringing in the "World imagery" basemap to this mxd again it aligns with everything apart from the ESRI 2D basemap. You can see below (transparency applied to World Imagery basemap with ESRI 2D below):

Re: ESRI imagery word 2D not projecting on the fly

NeilAyres — Thu, 17 Nov 2016 13:14:33 GMT

Been looking at the basemap data.

I have Imagery, Imagery with labels, NatGeo, OSM etc.

But I can't find one called ESRI Imagery World 2D.

Where is this coming from?

Re: ESRI imagery word 2D not projecting on the fly

Oliver_Burdekin — Thu, 17 Nov 2016 13:22:30 GMT

I've connected through arc catalog and the arcgis online server as I find basemaps draw more quickly using this method:

Re: ESRI imagery word 2D not projecting on the fly

JayantaPoddar — Thu, 17 Nov 2016 13:35:26 GMT

Add ArcGIS Server Connection for using the services (user)

http://server.arcgisonline.com/arcgis/rest/services

Re: ESRI imagery word 2D not projecting on the fly

NeilAyres — Thu, 17 Nov 2016 16:49:13 GMT

Well done that.

And if you look at them together, perhaps using the effects / swipe tool, you can see that there is an approx 70m offset between World 2d and the standard imagery (which is much better anyway). I was looking at some data in northern Zam around the benguelu swamps.

Why are you focusing on this 2d layer anyway? Data is data, somethings are better than others.

Re: ESRI imagery word 2D not projecting on the fly

Oliver_Burdekin — Thu, 17 Nov 2016 16:58:40 GMT

When data is data and it is not behaving I like to know why. And I think I've found out why. It would appear the ESRI 2D in that area is using the Arc50 to WGS84 transformation 7. Whereas all other comparable data I've looked at uses transformation 8.

Re: ESRI imagery word 2D not projecting on the fly

NeilAyres — Thu, 17 Nov 2016 19:45:59 GMT

Well, there you go. Someone messed up. Transformation 7 is for DRC.

But I am curious, I am just looking at both in a new ArcMap session, so the frame is still WebMerc (WGS84 based). There is an offset.

I think that the 2d layer is just badly referenced.

Re: ESRI imagery world 2D not projecting on the fly

MargaretMaher — Fri, 24 Aug 2018 22:06:48 GMT

If you are still interested in this question, I recommend downloading the list of Geographic Transformations linked to Esri Knowledge article 000004829, which includes the published accuracy of all the transformations we support. The accuracy of each transformation has been calculated by the agency or company that published the transformation, and Esri does not verify these values. However we do include them in the list for your convenience. As an example, the transformation Arc_1950_To_WGS_1984_7 has a published accuracy of 25 meters, and was calculated by the US Defense Mapping Agency. Generally their transformations are calculated from a single point, so the accuracy is not very precise. In the EPSG Registry, WKID 1119 is listed as being deprecated.

How To: Select the correct geographic (datum) transformation when projecting between datums

Another issue as well - back in 2016 when this question was posted, Google Maps were displaying data in Mercator on a sphere. There are no geographic (datum) transformations between any sphere and a datum. Recently, Google Earth has switched to Mercator on a datum, so transformations can be applied in Esri software to give better alignment.