Setup for a studio environment without source lights
Floor:
Create a circular surface with a gradient opacity map from grey to transparent.(outside)
Environment:
2-color gradient with nadir color slate grey (RGB 112/128/144) and zenit color white.
The .dgn file with environment settings and the opacity map can be downloaded here:
http://communities.bentley.com/products/microstation/microstation_visualization/m/luxology-files/131652.aspx
The same setup with adapted floor material:
Groundcolor: RGB 44/50/56
Specular 10
Reflection 5
When you disable camera and refraction for the gradient environment, a background image can come out trough the floormaterial with interesting effects.