KPovModeler 0.2

Written by Olivier Saraja (olivier_at_linuxgraphic.org)
English version

Working with Medias

There are still two checkbox options we haven't dealed with yet... While Medias are a stand-alone topic in themselves, needing a full incoming tutorial to explain and explore, here's what we could say in short: Medias are some sort of particles system (handy for simulating smoke, fire, dust and fog, for example) that can interfere with the lights of your scene, helping achieving volumetric light effects, such as making visible a ray of light. You are still puzzled? Okay, along with the kpovmodeler standard package comes some demo files. In /usr/share/apps/kpovmodeler/examples/scenes/interior you should find a file named media2.kpm which a very good starting point in order to learn what are and how do Medias work . The first picture below depicts this example scene mainly lit by a standard Spot Light . The second is exactly the same scene with a Media defined in order to simulate a fog of dust inside the room. Of course, the Medias parameters will define the density of the dust and many more aspects of it, but it's beyond the immediate scope of this study.

Media interaction: this checkbox states weither the light system should consider any Medias defined within the area lit. Set it 'on' if you want to achieve volumetric light effects, for instance, as on the second picture showed just before.

Media attenuation: with this option turned on, the light looses part of its intensity during its travel through the volume occupied by the Media. The third picture perfectly depicts that: Media attenuation is off and the room appears brighter than in the previous case, as light hasn't been impaired by the particles floating in the air. Of course, setting 'on' or 'off' Media attenuation is a matter of artistic choice as well as realism. If only simulating dust floating in the air, I'd suggest to simply set it 'off'. In the case of more meaningful particles, such as smoke or snow, setting it 'on' should be appropriate most of the time as these 'particles' could impair visibility.