LightWave is sometimes just too darned perfect. That's why we have features like jittering, lens flares, and motion blur - to create some of the imperfections that reality provides us. Volume one of Realitools gave you nice soft reflections - much more realistic than the 'perfect' raytraced reflections that LightWave normally creates. You can think of translucency as the cousin of Soft Reflections; it sorta does for refraction what Soft Reflections did for reflection.
The trade off is longer render times. The Tranlucency plug-in is performing a lot of complex math and so it does take its toll. This is especially so when you're looking through multiple translucency surfaces - be very careful and don't say we didn't warn you. With this in mind, intelligent use of Tranlucency can add an extra level of realism to your LightWave scenes.
Let's take a look at a couple of examples of images using translucency on one sphere and the other using standard LightWave refraction tools.
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Okay, you're convinced - it's cool. We didn't change many settings, either. The Angle Step setting was set to 3, and the Radial Samples was set to 10. The Refractive Index for the material was set to the amount specified in each image. AutoFresnel was turned on. And that's about it.
Blur Angle, Angle Steps, & Radial Samples
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Like the Soft Reflections plug-in, Translucency works by tracing multiple rays and 'scattering' them, which creates a more realistic and organic effect than LightWave's built-in method.
Blur Angle determines how much scattering takes place. If you look at the example, you'll see that the sphere with a setting of 4 is much blurrier than the setting of 1. The number represents the amount of blurring in degrees.
Angle Steps and Radial Samples work together to determine how many rays are traced. The formula used is:
So - an Angle Step of 3 and a Radial Samples setting of 10 would be tracing 31 rays - and the higher the number of rays traced, the longer your render times will be. As with any ray tracing, it's always a matter of finding the best trade off between image quality and speed. If you look at the example frame, the difference is pretty obvious - the sphere with the higher setting has more detail and looks smoother.
So, what do the settings mean? Translucency achieves its effects by tracing rays in a cone shape. Radial Samples determine how many rays are traced around the cone's edge. Angle Steps creates a series of 'nested' cones. Generally, you want to keep your Angle Steps number fairly low (1-4), and your Radial Samples around 6-12. Steps of 3 and Samples of 10 gives you a nice look for most video-resolution work, although a number of the examples on this page (such as the tint examples below) use Steps of 2 and Samples of 8, and it looks just fine, too.
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In real life, surfaces refract differently in different environments. In its quest for realism, Translucency gives you the option of setting an Index Of Refraction (IOR) for both the surface and for the world. (It also offers a nifty list of common IORs, so you don't have to consult an outside reference - you can use the plug-in as a quick reference, in case you don't have IORs memorized, ya wimp.) You can also have different World settings in the same scene, as the example shows. (Fog was added to the scene just for kicks.)
Picking an IOR is as easy as it could be - just select what you want and go. Or, enter your own IOR if what you want isn't covered in the list. Note also that you don't need to have LightWave's 'Trace Refractions' on for the Translucency plug-in to work.
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You also have the option of tinting your Translucent surface. There are two options, one that lets you pick an RGB color, and another that allows you to use the surface's colors as chosen in the LightWave surfaces panel.
The first example shows a straight tint using RGB values selected from within the plug-in. It also points out a problem with using a tint with the AutoFresnel feature - namely, you get a non-tinted edge on the object. One solution is just to turn off the Auto Fresnel feature. Example two shows the tinted sphere with and without AutoFresnel.
The third example shows the results of using Tint From Surface, with a fractal noise surface selected in LightWave's surfaces panel. One important note - you must go to the Basic Parameters section of the surfaces panel and have the Color Filter button turned on for the Tint From Surface effect to work.
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Jitter Samples creates a smoother, more anti-aliased looking effect by adding a random angle to each ray that is traced. You'll generally want to use it.
Finally, AutoFresnel is a quick and easy way to get a Fresnel effect on your Translucent surface. The effect is very visible at the edge of the sphere, where the AutoFresnel-ed sphere has an 'edge' to it.