TUTORIAL
This short tutorial shows steps to obtain green shpere rendering.
Run 3ds max and set scene in cm, that will help us in understanding caustics setting units.
Fig. 03 - File units.
Now create scene elements: Plane, Standard camera, Geosphere and Spotlight.
Fig. 04 - Four elements in our test. Look at large plane size.
The "rock" is a dense geosphere with Noise modifier on.
Fig. 05 - Deformed Geosphere params.
Camera is a simple 3ds max Standard, while light is a slight modified Spot.
Fig. 06 - Changed Spot light params.
We won't use
Global Illumination in this test, because we just need to understand how getting volume caustics. Adding
GI will waste time. though not strictely necessary, set
LWF here too.
Fig. 07 - Setting panels.
As we can see, many setting has been left as default. Main stands in caustics. Following settings in study scene.
Fig. 08 - Photon Map settings.
A quick explanation to simple params. You can find a caustics videotutorial
here.
Multiplier: as standard light multiplier, increases or decreases caustics intensity. Makes them lighter, brighter. Modifying value won't request new
PM calculation. In fact, once computed, it can be stored and used again, just like happens with
IM and
LC. to achieve physically correct results use 1, but feel free to change it.
Max density: figure
Max density as a grid size. Lesser the value, denser the grid; we'll get better quality spending more photons for "clean" caustics. Smilar to radiosity rule, with high-divided meshes we get precise solution at cost of time.
Search distance: setted grid size,
VRay computes and interpolates photons. Higher
search distance value means more photons in interpolation algorithm; giving blurred caustic with definition loss.
Max photons: maximum photon number
VRay uses to blur
PM. If
Search distance uses distance among photons,
Max photons uses their number. Both can be modified without new
PM computation.
Last important parameter for
PM generating, physically defines photon number
VRay uses in
PM estimating. Since photon emitter is light based, last param is in VRay light properties.
Fig. 09 - Reach this panel following V-Ray properties, clicking right on selected Spot light. We use 2.000^2 photons.
Run render on a DualXeon Quadcore 3.2 ghz.
Fig. 10 - We get caustics in 9 seconds + 30 for PM.
Add
VRayEnvironmentFog (
VEF).
Fig. 11 - The volume effect.
See both volume light cone and volume caustics in render.
Fig. 12 - Last rendering, got in 59 secs + 30 for PM, necessary in VEF's checked.
If you want, you can use hidden VRay feature with maxscript:
renderers.current.caustics_showCalcPhase=false
In order to run progressive and high-precise caustics computation. A deeper explanation in my
videotutorial.
Same rendering needing 12 minutes. First rendering shows pure volume caustics (reported timing is wrong), second final rendering.
Fig. 13 - Final rendering with progressive caustics.
Resulting caustics are very precise, but cause higher noise. rule is quite similar to
PM and
PPT.
Hope you are enjoy with my little tutorial. In attachment the video.
See the next time
Ciao
Francesco Legrenzi.
www.francescolegrenzi.com
