Every now and then we'll be documenting how we did something - sometimes it's to share a 'behind-the-scenes' and sometimes it's just so that we can keep a record in case our short term memories fail us...
Shader glow adds the appearance of the blooming of light due to high contrast or strong intensity. By default, when you enable glow in Maya, the entire surface of the object glows equally – not too realistic. In most cases, you only want the specular area to glow and you can do that by going into the Hypershade or Multilister -> Pick the Shader Glow Node-> Locate Threshold in the Attributes panel. A larger version of the above image can be found at this link: widgetGlow
Try increasing the value and as it is raised, only the specular highlights will then bound the apparent glow effect – a more realistic look. But beware, Maya only allows one SG node per scene, and the values you set are global. On occasions, you may find yourself having to render different passes for different surfaces.
NOTE: For all “glow” effects, a good idea is to render your glowing objects in a separate render pass, not relying on the Maya glow effect at all, but rather to use blur and add effects in your compositing software. This can allow for much greater control over glows and diffusion effects. The artists at Atomic Fiction have a good blogpost on this subject: