lighting guide
http://media.digitalcameraworld.com/wp-content/uploads/sites/123/2015/09/Free_portrait_lighting_poster.jpg
http://blog.digitaltutors.com/understanding-three-point-lighting/
http://www.3drender.com/light/3point.html
http://www.predatron.co.uk/three-point-lighting/
http://www.cgarena.com/freestuff/tutorials/maya/beauty/index.html
https://www.youtube.com/watch?v=UlfcIIFD0WU
https://www.youtube.com/watch?v=Vrb9lEFy6ro
https://www.youtube.com/watch?v=2Dg9bi9fCe8