I received a 22GB Raster .tpk image with a WGS 1984 Web Mercator (aux sphere) projected coordinate system, how can I change this to NAD 83?

[EmilyAiken]

I am using ArcPro to match this image raster projection with the NAD 83 State Plane California iv projection of my vector data to create a basemap. Have already tried "Project Raster" tool and it never processed a newly projected raster... 

[DavidPike]

That sounds like a nightmare.  It would probably involve Export Tile Cache to Exploded format, then reprojecting all of the rasters.  The next step would be recreating the tile cache or tile pack with a tiling scheme file set to NAD83 Cali.

You might be able to add the tile pack to a mosaic dataset, force a reprojection and then generate a set of overviews

Just ideas, there may be a simple way, I'm not sure.

[EmilyAiken]

Thanks David, I set the map environment to the NAD 83 CA coordinate syst, and the line vector data seems to be "lining up" nicely over the hi res imagery, however some of the polygons are slightly off. I am hoping there is a way I can just go ahead and use this tpk with it's original projection to create my basemap.

Otherwise, I do have the original single image files from the drone flight (one set of RGB and one set of CIR), but orthorectifying these is a bit out of my wheelhouse... 

[DavidPike]

Agreed, I would only look at doing so if I had no other option and it was worth the effort.  As to projecting on-the-fly - there may be a better transformation which you can specify, but US coordinate systems are out of my wheelhouse!

Apply a coordinate system transformation:

To apply a transformation, right-click the map or scene in the Contents pane and click Properties. On the Map Properties dialog box, click the Transformation tab.