Before changing the background, make
sure that photometric lighting is enabled:
Click Render tab Lights panel American Lighting Units
Click Render tab Lights panel International Lighting Units
Click View
tab Views
panel Named
Views. At the Command prompt,
enter view.
In the View Manager, click the view name
you want to change. If the view isn’t already displayed, expand
the appropriate View list, and then click a view name.
In the Properties panel, click the Background
Override field.
In the Background Override drop-down
list, select Sun&Sky.
In the Adjust Sun & Sky Background
dialog box, specify the desired options for the background.