Can you override basemap projection of Portal web map item?

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06-25-2020 09:28 AM
Arne_Gelfert
Regular Contributor

Sorry if this question's title isn't clear. I feel a bit out of my depth on this one. Got to this point via a somewhat convoluted route...

Background:

Trying to migrate old AGS map services to Portal. These maps appear to be derived from CAD drawings and features were reprojected to essentially line up with the page or window of the GIS application. So what you see in the map does not match the real world alignment of features. The originals are in MXD form and there is no rotation in data frame. The original map services apparently accepted this transformation and showed the features in the desired "format".

When I import MXD's into ArcGIS Pro (2.5), everything looks good. When I publish to Portal, everything still looks good. Map services show the feature transformed as desired. But when I create a web map from these web layers in Portal, everything apparently gets forced into the basemap's projection and all the sudden everything appears rotated back to its real world alignment.

Question:

Is there anyway to override this - to make the webmap use the map service's projection? I don't see that there is a way to remove the bsemap. The ESRI definition of webmap sorta implies use of one. There is virtually no way to do anything else through Portal interface. But I see that through Python API I can get a reference to the webmap. However, it shows that the property

'spatialReference': None,

Is there any way to use a different projection from basemap?

Ultimately, I'd like to build an app in Web Appbuilder with these layers, so maybe I could configure this over the mapOptions in congif.json and the spatialReference there? I haven't looked at that yet.

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DerekLaw
Esri Esteemed Contributor

Hi Arne,

> But when I create a web map from these web layers in Portal, everything apparently gets forced into the basemap's projection and all the sudden everything appears rotated back to its real world alignment. ... Is there anyway to override this - to make the webmap use the map service's projection?

What you're asking to do specifically: "make the webmap use the map service's projection" is not possible, but there is a workaround to address the projection issue.

FYI: a web map always uses the basemap to define its spatial reference and projection. So if you want to use a custom projection, you need to define your own "basemap" map service. You can create your own map service in the desired projection, then publish to Portal for ArcGIS. Then use it as part of a group with custom basemaps that you can set in the Portal Map Viewer.

Customize basemaps—Portal for ArcGIS (10.8) | Documentation for ArcGIS Enterprise 

However, this means you have to provide the data for your own basemap and you can't use the esri provided basemaps.

Hope this helps,

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3 Replies
DerekLaw
Esri Esteemed Contributor

Hi Arne,

> But when I create a web map from these web layers in Portal, everything apparently gets forced into the basemap's projection and all the sudden everything appears rotated back to its real world alignment. ... Is there anyway to override this - to make the webmap use the map service's projection?

What you're asking to do specifically: "make the webmap use the map service's projection" is not possible, but there is a workaround to address the projection issue.

FYI: a web map always uses the basemap to define its spatial reference and projection. So if you want to use a custom projection, you need to define your own "basemap" map service. You can create your own map service in the desired projection, then publish to Portal for ArcGIS. Then use it as part of a group with custom basemaps that you can set in the Portal Map Viewer.

Customize basemaps—Portal for ArcGIS (10.8) | Documentation for ArcGIS Enterprise 

However, this means you have to provide the data for your own basemap and you can't use the esri provided basemaps.

Hope this helps,

View solution in original post

Arne_Gelfert
Regular Contributor

Thanks, Derek... hadn't really given that any thought. Will try it now. Since I don't have much need for a basemap with this app anyway, this could be work out to my advantage. Thanks for the suggestion.

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Arne_Gelfert
Regular Contributor

Derek, finally getting back to this... your suggestion worked great. Thanks again.