Typing a negative Z unit conversion factor on the Base Heights tab for a raster, when its base surface is also a raster, results in an image whose top looks dark and the underside is light. The top should be light.
This is a known issue.
Solution or Workaround
ArcObjects Online contains a developer sample that can be used to factor the base raster surface.
- Click the link below and expand Samples > 3D Analyst > Surface Analysis.
- Download the Raster Math Command sample. You can use this sample to multiply a raster by any value.