To create a fog effect in your rendering, you need to turn on the Fog option in your rendering settings before rendering the view.
To create a fog effect:
Select View
> 3DTrueView > 3DTrueView Options, or click the 3DTrueView
Options button on the 3DTrueView toolbar.
In the Program Settings dialog, select the Rendering tab.
In the Effects area, check the Enable check box.
Enable the Fog radio button.
In the Density edit box, specify the desired thickness of the fog. The higher the percentage, the thicker the fog.
Click OK.