#SecondLife Global Illumination

You may not have noticed the Graphics Setting feature: Global Illumination. It began appearing in viewers some time ago. But, now it has disappeared from the SL Viewer. So, what’s up?

What it is…

Global Illumination is the label used to describe how light is handled in 3D games. Its purpose is to make lighting more realistic. It adds ‘reflected’ light effects. This means if you are standing with a blue wall to the right and the sun to the left, some blue light will be reflecting on to your right side.


Back in May 2009 the Lab, Runitai Linden, posted a video showing new features they were working on. See: SL Tech Demo above.

The video (above) includes Mesh and Global Illumination. At about 1:34 in the video you can see a sun cycle that shows an example of Global Illumination. (GI) Notice how the sun seems to reflect off surfaces and illuminate other surfaces. That is the Global Illumination.

Mesh and GI were in development at the same time. Mesh has been released and GI began to appear in viewers too. But, there were problems with it and most viewers carried a warning that one needed a top end computer to use the feature.

It takes considerable computer power to quickly calculate light reflections. The result is most of us never turned it on.

Oz Linden explained why the controls for GI were removed from the viewer interface.

It’s not a good idea for us to leave in half-finished features that tempt users to try them and make the viewer less reliable.   While we might attract a very small number of enthusiasts who don’t care that the viewer crashes, we’ll just confuse and alienate a much much larger number of normal users who don’t know what it is, don’t care, and suffer from the added complexity of the viewer code and consequent instability.

The viewer is open source – the enthusiasts are more than welcome (indeed, encouraged) to build bleeding-edge experimental features in third party viewers.  I stand ready to advocate for integrating those that prove themselves.

Normal users… OK, I know what he means and can understand the Lab’s viewpoint.

[youtube yszc_Bp_Fu8]


Global Illumination is not something I used. My 8800 fell to its knees with GI turned on. I haven’t tried it since getting a new video card.

It is buggy and people have various problems with GI enabled. So, for now the Lab has removed it from the user interface. Whether the code is still in the viewer or not, I just don’t know. I do know that the GI Debug Settings are not in the SL Viewer Dev 3.2.5-(246465).

  • RenderGIAmbiance
  • RenderGIBlurBrightness
  • RenderGIBlurColorCurve
  • RenderGIBlurDistFactor
  • RenderGIBlurEdgeWeight
  • RenderGIBlurIncrement
  • RenderGIBlurSize
  • RenderGIBrightness
  • RenderGILuminance
  • RenderGIMinRenderSize
  • RenderGINoise
  • RenderGIRange

Presumably GI is still in the list of things the Lab would like to develop. Priorities seem to have placed other projects ahead of GI.

One thought on “#SecondLife Global Illumination

  1. I believe Oz is giving the official view – Runitai Linden removed it while doing the fix for the OpenGL issue with recent Nvidia drivers – I think it is more related to the feature using deprecated OpenGL calls.

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