Black Body Colour/Brightness Nodes (cycles)

  • April 06, 2014
  • 590 Downloads
  • 5 Likes
  • Blender 2.7x
  • Render: Cycles
  • Creator: Moony
  • License: CC-BY
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Description:

Edit: I have added an animation showing this node group in action. The only parameter changed during this animation is the input temperature.

https://www.youtube.com/watch?v=d7XK31Vmg7E&feature=youtu.be

Cycles already includes a black body node to convert temperature into colour (hotter temperatures are less red and more blue) - however in the real world, the brightness of an object also increases with its temperature (the the 4th power) according to Plancks law. My node setup also goes to a higher (bluer) temperature than the unbuilt node which is limited to 12,000K.

This node setup uses a colour ramp to convert temperature to colour according to the conversions given here:

http://www.vendian.org/mncharity/dir3/blackbody/UnstableURLs/bbr_color.html

It also contains a factor to increase the brightness with temperature. The node group has the following inputs:

Temperature = Temperature in Kelvin (between about 700K and 40,000K). Every day lights have a colour temperature around 2500K.

Exponent = Controls the rate at which the brightness increases with temperature. To by physically accurate its defulted to 4 (doubling the temperature increases the brightness by 4 times). Lower values will make the brightness ramp up slower (e.g. 2 will double the brightness as the temperature doubles)

Cutoff temperature = this is a lower bound to the temperature below which no emission will occur.

Brightness = Controls the overall emission brightness (Lower values = dimmer)

Comments:

  • Mikel007 profile picture
    Mikel007

    This is a very useful Node-setup. Great work and thank you very much for sharing it with us. It's really beater than the blackbody-node.

    Written April 08, 2014
  • Stiegosaurus profile picture
    Stiegosaurus

    Thank you man! Very useful

    Written December 19, 2015