TUTORIALS
LIGHTING (BASIC)

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IN THIS SECTION WE`LL DISCUSS ALL TYPE OF LIGHTS AND STRATEGIES TO HANDLE THEM PROPERLY. THIS TUTORIALS IS BASED ON MY EXPERIENCE WITH MENTAL RAY AND PRMAN, BUT COULD ALSO BE USED FOR OTHER PACKAGES WITH SIMILAR FEATURES.

WAY OF LIGHT

FIRST OF ALL YOU HAVE TO KNOW HOW LIGHT BOUNCES TO SIMULATE IT CORRECTLY.

DESCRIPTION: LIGHT XY SENDS A RAY WITH 100% INTENSITY. THIS RAY LOOSES INTENSITY BASED ON THE FALLOFF. WHEN IT HITS A OBSTACLE IT GETS REFLECTED/TRANSMITTED. THE INTENSITY OF THIS BOUNCE DEPENDS ON THE TYPE OF MATERIAL IT HITS. POLISHED METAL FOR EXAMPLE REFLECTS 50%-70% INTENSITY. A DARK FABRIC WON`T REFLECT THAT MUCH, JUST ABOUT 10%-30%. NEVER FORGET TO THINK ABOUT THE LIGHT ANGLE (ORANGE ARROW) )WHICH DEPENDS ON THE MATERIAL ROUGHNESS. HIGH ROUGHNESS MEANS THE LIGHT WILL BE STRONGLY SCATTERED ON THE SURFACE THEREFORE THE LIGHT WON`T FALL IN A SINGLE DIRECTION.

NOW WHATS ABOUT MATERIALS WHICH ARE TRANSPARENT?. THE LIGHT WILL BE SCATTERED THROUGH THE VOLUME. OF COURSE THE INTENSITY AND SPREAD OF THE LIGHT DEPENDS ON THE MATERIAL.

THE BIGGEST PROBLEM BY LIGHTING SCENE ARE AREAS LIKE CORNERS. CORNERS BLOCK LIGHTRAYS WHICH MEANS: SMALLER ANGLES/DISTANCES BETWEEN OBJECTS RESULTS IN DARKER AREAS.

THIS PICTURE WAS RENDERED WITH MENTAL RAYS FINAL GATHERING. ONE SPOTLIGHT WITH HARD RAYTRACED SHADOWS WAS USED, AND ONE SURROUNDING LIGHT-EMITTERING SPHERE.

 

 


LIGHT TYPES

THERE ARE THREE COMMONLY USED LIGHT TYPES IN EVERY PACKAGE:

1. INFINITE LIGHTS
2. POINT LIGHTS
3. SPOT LIGHTS

 

INFINITE LIGHTS

MOST TIMES USED TO SIMLULATE THE SUN LIGHT, BECAUSE ITS PARALLEL.

MOST PEOPLE FORGET THAT AN INFINITE HAS NO POSITION JUST AN ANGLE. YOU HAVE TO EXCLUDE ALL SURROUNDING OBJECTS LIKE A SPHERE REPRESENTING THE SKY (WHICH WOULD BLOCK THE LIGHT(WITH ACTIVATED SHADOW ). ANOTHER SOLUTION WOULD BE TO SPLIT THE LIGHT AND SHADOW CREATION <TUTORIAL>.



POINT LIGHTS

MOST USED FOR BOUNCE, FILL LIGHTS.

A POINT LIGHT IS VERY INEFFICIENT WHEN IT COMES TO SHADOWS. THE ONLY EFFICIENT POSSIBILITY TO USE SHADOWS ARE TO RAYTRACE THEM. IF YOU CHOOSE SHADOWMAPS THE RENDERER HAS TO RENDER 6 DEPTHMAPS, AND IF YOU USE SHADOW SOFTNESS YOU`LL NOTICE SOME BAD ARTIFACTS AT THE STICHES OF THE DEPTHMAPS.


SPOT LIGHTS

USED FOR EVERYTHING.


 

I USE THEM AS SHADOW AND BOUNCE LIGHTS. BIG PLUS IS THAT YOU CAN LIMIT THE AREA IN WHICH THE SHADOW FALLS (SPECIALLY FOR SHADOWMAPS). HOW TO USE THEM AS BOUNCE LIGHTS:


* SET THE CONE ANGLE TO 0 AND THE SPREAD ANGLE AS YOU NEED IT.
* TURN SHADOWS OFF
* CHOOSE A PROPER LIGHT COLOR REPRESENTING THE "EMITTER MATERIAL"
* PLACE IT INSIDE THE OBJECT / BELOW THE GROUND FACING TO THE RIGHT ANGLE

 



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