Hi , i’ve been studing many things about yafray and i still dont get it right , there are so many concepts , GI , Raytracing ,Radiosity etc…
It would be great if someone who knows how to use yafray would do a good video tutorial about it , i would even pay for one .
It would be great if someone would do a dvd or a cd , men i really would buy it .
do you know of any video tutorial on the net , i’ve been looking but i dont find.
Have you checked out the knowledge base at www.yafray.org?
It is a really good one, with excellent tutorials and explanations on lighting and of course about the features of yafray. And a search here might help as well.
You shouldn’t stick too much to yafray though, the techniques you’ve mentioned are used by many rendering engines and the same principles apply anywhere, so you’ll find even more informations on the whole web.
And finally don’t forget that it is not only about the engine either. Good lighting is a matter of the setup, not of the rendering algorithm (you find some good stuff here: http://www.itchy-animation.co.uk/light.htm or here: http://www.warpedspace.org/lightingT/part1.htm ).
So, yeah, I fear, if all that doesn’t help you, a video tutorial won’t do it either - good luck!
Yes, we lack good tutorials for beginners, that’s true. I hope to remedy it this year. Tell me what tecnique are you interested in and I will make you a brief summary.
Besides, I agree with Myke, it your lighting sucks, it will keep on sucking not matter what render engine you use.
hi , well i would love to have a tut where is explained the process for a indor scene and an outdoor scene , the problems you can find in the way and well just to see how its all done.
Get trained in traditional lighting setups first (3PT lighting), learn to simulate bounce lighting with spotlights. Don’t use raytracers ‘to save time’ in lighting desing. If a lighting setup is poor, it won’t work no matter what render engine you choose the most of the times. Once you know some essentials about lighting, then consider using a raytracer.
1. Indoor scene, using Path tracing (yafray Full GI) + Photons + Irradiance Cache
Use objects with ‘Emit’ Material plus Arealights to simulate light sources. Place arealights in windows. Explained here:
http://wiki.yafray.org/bin/view.pl/UserDoc/YafRayLighting#Emitting_objects
Those arealights will act as photon emitters.
Don’t touch ‘GI Pwr’ default value (1). GI power should only be tweaked as last option, too large values break any physical concept, lowering should rarely be necessary unless your materials are way too bright.
‘Exposure’ and ‘Emitpwr’ are the most important settings to control lighting power. Explained here:
http://wiki.yafray.org/bin/view.pl/UserDoc/FaqEng#Q11_Why_does_YafRay_renders_imag
Since photon mapping is scale dependant, the most important values to get a good photon map are ‘radius’ and ‘mixcount’ and not a hight number of photons to shot, like people tend to believe. You can set a huge number of photons to shot and still getting a poor result.
A very low ‘Pregathering’ value (less that 50.000 photons) usually means that your photon map is not optimised for the scale of that scene. I would say that a good pre-gathering count should be at least a 10% of stored photons, like in the screenshot below, and 100.000 photons as minimun. Lower ‘Radius’ and increase ‘Mixcount’ to get higher ‘pre-gathering’ counts. Use the 0.5<>1.5 range for ‘Radius’ and 100<>150 for ‘Mixcount’ (more or less 
)
Once, these steps are completed, increasing GI Quality and using Shadows Refinement to avoid artifacts in corners and joints should be enough to get a good render. I usually start tweaking parameters with a ‘Medium’ GI Quality and increase it at the end. I recommend tweaking the photon map parameters with 50% gray matte objects in the scene as reference, because bright objects usually tend to hide more the sampling paterns.
Launch a render with a calibration card textured plane in the scene to see whether the lighting is balanced or not. Use this for instance (below). You should get the they gray shades and colors more or less like in the image (depending on the lighting power too):
Other people uses a set of different grey objects (with different % of black) to balance the lighting of a scene.