A parabolic reflector carefully modeled with a Maxwell Render emitter placed at the calculated focus point of the parabolic reflector. As expected, a strong beam of light emerges.
My puzzling initial parabolic reflector test in which the light traveled in a spreading cone. Turns out I had left the reflector material at Maya default Lambert gray. Oops.
A 'control' image in the experiment: the bare emitter. It is placed in the ideal location for the parabola focus, and it never moves nor changes brightness during the tests.
Is an ellipsoid of the same mouth width and depth an adequate substitute for a parabola? Lets see. Note: the light is at the ideal location for the parabola focus. The light is not intentionally at one of the ellipse focus points.
We are accustomed to seeing flattened parabolas, or the bottoms of parabolas - that is to say, cup-shaped parabolas.
This one is y = 0.5 * x^2 and its exact focus is at (0 0 -5)
(A parabola of 0.5 * x^2 is obtained by scaling a parabola of y = x^2 by 0.5)
We usually focus on their curved tips, but in 'the big picture' parabolas are practically cylinders - nearly parallel walls racing off to infinity. This one is y = x^2, which is a handy known starting parabola from which to precisely derive any other more useful parabola shapes.
Here is a .obj file of parabola y = x^2 for you to download.
Here is a .mb file of parabola y = x^2 for you to download.
See the .OBJ file and Maya .mb files above.
When I was a kid a high school classmate of mine once remarked, "There really is only one parabola. We just see it at different magnifications." I always thought that was a pretty wild way of looking at it. -- and yes, my high school was pretty geeky :D
Wow. This is extremely useful. I've been trying to simulate some L.E.D. fixtures and was just sort of free-handing the reflectors and not getting very good results. This explains why! (and shows how to do it right). Thanks so much!
Thank you.
Look under the long carrot-shaped y=x^2 parabola screen grab and you'll find links to a Maya scene file and .obj format file. If they are useful, feel free...
:)