Why Does My Rendered Image Appear Too Bright or Dark?

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:

• Brightness is too high or low. - Adjust the exposure value of the rendering environment.
  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.
• Generic lights were added to the drawing instead of photometric (physical) lighting. - LIGHTINGUNITS is currently set to 0, and should be changed to 1 or 2.
  Note: Starting with AutoCAD 2016-based products, the renderer only supports photometric (physical) lighting.
• Intensity of user-defined lights is too low or high. - Adjust the intensity and direction of the lights in the scene.
• Materials are too light or dark in color, or have a low or high refraction value. - Adjust the color or refraction value of the materials.
• Background color is pure white or black. - Change the background color of the scene or disable the use of image-based lighting for the background of the rendered image.
• Image-based lighting is incorrect for the 3D model being rendered. - Select a different image-based lighting map or disable image-based lighting.