Most users are familiar with Ambient Lighting, which is controlled either under View > Set Lighting Options, or controlled within the Lighting tab when editing a Renderworks Style:
This lighting color and brightness can be controlled directly, but generally would be disabled when attempting a photorealistic rendering style, so that all the light comes only from Light objects, Heliodons, Renderworks Backgrounds or Glow textures.
However, if you have no Light objects present within the document, a feature called Default lighting appears which prevents your renderings from appearing completely black, but if you are not aware of its existence, it can cause undesired results. Default lighting is overridden as soon as you insert a light object, and if you do want your rendering to appear completely black, turning off all Light objects within the document will do so.
If your only intended light source is a Glow texture however, and you wish to disable Default lighting, the easiest way is to add a single light object, then turn it off.
Ambient On, Default On is the normal state of a new blank document in Vectorworks before any lighting options are altered or any light objects added:
Ambient Off, Default On is what happens when you have no light objects, but have manually disabled Ambient lighting in the render style or in Set Lighting Options for the document and is the state the above tip helps you avoid:
Ambient Off, Default Off is what you get when you add a light object, but turn it off, and also have Ambient lighting disabled in lighting options. This is a "perfect" darkness which if you were inside a room, would be pitch black other than the 3D background color, white in this example:
Edited by JimW