The DigitalGlobeImagery is very blurry when zoomed in.
TBC Help content is providing the following information regards to Toggle Background Map:
To see or change the sources of map data that are shown behind your model:
Warning: Some map data sets are more current than others. Independently confirm that the background map is current enough for your geographic reference needs. Cached maps are removed from your local program files periodically to accommodate newer updated maps.
Retrieving data ...