Even though the beam of laserlight is usually not seen in real life, it is often nice to visualize them in rendered images. This little example will provide enough information to generate a laserbeam that is constant with a nice glow attached to it. If you want to make a laser that is visual only in smoke (which more closely resembles the bahavour of a real life laser), take a look at Laser II. This laser have three parts;
- a lightbeam (which is visible only to the objects it affects)
- a cylindrical (real life lasers have an extremely narrow cone) beam object
- a cylindrical glow object
The lightsource is only visible by the object it hits, and not at all to the naked eye. The normal belief is that the laserspot is of equal diameter no matter the distance, but the truth is that it is not that perfect. For instance, the laserlight shot at the moon (to measure the distance) is several meters wide when it hits the surface of the moon. However, we will use cylinders to do the work. Lets create the objects:
- Create a cylinder, say, 1.0 meters in diameter, and hit 'B' (boolean OR) to make
it a level
- Create another cylinder, say, 0.25 meters in diameter, and hit 'B' (boolean OR)
to make it a level
- Create a beam lightsource with 1.0 meters in diameter
For the fake glow it is natural to make a turbid (foggy) material with a high turbid saturation level, so that as the cylinder thickness drops off out in the egde, the fog looses effect, and such becomes more transparent. This is true and works great when viewed from the side, but if you position the camera so that you look along the cylinder axis, the effect of turbidity will inrease with distance. Since Real 3D is an animation package, there must be a way so that the viewing angle doesn't effect the tubidity level, but still has some amount of falloff, and this is off course possible. Instead of using turbid saturation for the falloff, we will make the turbidity change according to the depth in the cylinder.
The laserbeam material is 'unshaded', 'fully white ambient', 'col. repl' in the color handler, with 255, 0, 0 (red) value in 'Transp, RGB'.
The laserglow material is a bit special, so I will go more in detail here. Brilliance, transparency, refraction, and effect is set to 100. We don't want any reflection, so set the 'smooth' toggle on. As a laserbeam is not affected by light, set the 'unshaded' toggle on. Set the scope handler to formula and write the following: tu=b-b*y with 'b' set to the ratio between the two cylinders, here 0.25. What happens is that tu increases as it gets smaller. So, in the outer layers the fog is very thin, but close to the beam, it gets more and more thick. Set the color handler to formula and write the following: G=255*y, B=G.
What this does is fade the white (outer) color to a more reddish one towards the center. It wouldn't be possible just to have a red object, as this would filter the background and make a clear boundary. Below is a couple of pictures with a laser beam generated with this method. Remember, no glow post-effect is used.
Examples of a laser made with the above method |
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| Fig. 1. Laser shown from some distace | Fig. 2. Laser shown from very close to the beam |
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