Surface Layer - Luminosity Tab

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Surface Layer - Luminosity Tab

The Luminosity tab has settings enable you to make a surface glow. The glow is like a light being emitted from the surface. It will light up other parts of the scene as well.


  • Luminous: Check this checkbox to make the surface glow. The settings to the right allow you to control the amount or strength of the glow effect. Larger numbers mean a stronger glow.
  • Luminosity tint: This lets you set the colour of the glow. You can make the glow colour different to that of the surface as a whole.

  • Luminosity function: This lets you assign a function or shader to control the luminosity effect. There are several ways you can use this to control the effect.

    The simplest way is to use a greyscale function. You could use a Painted Shader to paint areas you want the glow. You could use an Image Map Shader to load an image to use as a mask. White areas will have glow, black areas won't have glow. The colour of the glow will come entirely from the Luminosity Tint colour.

    A more advanced way to is to use a colour function or shader. You might use an Image Map Shader to give a complex multicolour glow effect for example. In this case the overall tone of the image will control the strength of the glow. Darker areas will have less glow. To get the actual colours from the image you will want to set the Luminosity Tint to white. This is because the tint colour is blended with the colour from the function. You could set the tint colour to a grey value to reduce the strength of the glow from the function. This is more like fading the image out rather than directly controlling the string as you would do with the Luminous parameter though.

    Finally you can use a combination of the Luminosity tint and a colour function or shader to modify the final glow colour. The two colours get blended together. For example if you used a yellow Luminosity tint and a magenta colour in the function you would end up with a peachy/guava coloured glow.

    As you can see the combination of the Luminosity tint and Luminosity function can be quite powerful and the interactions complex. Here's a quick run down on how to use achieve the most common results:

    Use the Luminosity function to control where the glow effect appears
    Use a greyscale function or shader as the Luminosity function. More glow will appear in the light parts. The colour of the glow will be set entirely by the Luminosity tint.

    Use the Luminosity function to control the colour of the glow
    Use a colour function/shader/image to give the colour of the glow. The tone of the image will control where the glow appears. Darker parts of the image will have less glow. Set the Luminosity tint to white to let the colours from the image come through untouched. Change the Luminosity tint to a grey value to control the intensity of the image colours.

  • Back to: Surface Layer

A shader is a program or set of instructions used in 3D computer graphics to determine the final surface properties of an object or image. This can include arbitrarily complex descriptions of light absorption and diffusion, texture mapping, reflection and refraction, shadowing, surface displacement and post-processing effects. In Terragen 2 shaders are used to construct and modify almost every element of a scene.

A parameter is an individual setting in a node parameter view which controls some aspect of the node.