The brightness level in which a 3D model is rendered can be affected by a variety of lighting settings and even material choices.
The following outlines some of the conditions that could affect the brightness of a rendered image:
If the SUNSTATUS system variable is set to 1, the scene can become too bright resulting in the rendered image appearing white with no objects. Disable the Sunlight system or adjust the exposure setting in the Render Environment & Exposure palette.