[Cosmasad]

Good morning everyone,

We are a group of architects working in Washington, D.C. on a restaurant interior. There are 110 different lights in the restaurant, -- 50 tracklights with MR 16's, 40 downlights with floods, and 40 table lamps. We are following up on a message that we posted in another part of the forum.

We understand the concept of the emitter material, and have been told that when creating a light, it is best applied to a sphere 1 cm diameter. This is all well and good, but intuitively it seems that a sphere that has emitter material applied to it would radiate light evenly in all directions. It would glow in all directions. We have been told, however, that "the sphere is like any other geometry, you can manipulate its position and rotation -- the IES material will follow where the sphere points once it is applied." But the sphere doesn't point... it is perfectly round. Then Daniel posted that "if you are in studio you should immediately see the ies distribution diagram in the viewport (blue dots) after applying the emitter material to the sphere(s)." It seems that the ies function is not supported in Rhino yet. Can anyone tell us if there is a workaround for this. Should we be working in Studio instead?

Somebody else said that "the normals of the Sphere will determine where the light is pointed -- after you apply the material just move and rotate the sphere like a flashlight/spotlight..." but again-- a sphere glows in all directions evenly. Could it be that people are using the word sphere to mean a circular surface 1 cm in diameter?

Your assistance with this would be appreciated.

Thank you.


Cosmasad

[Half Life]

What IES file are you attempting to use that will glow equally in all directions? -- that totally defeats the purpose of using an IES file...

You will understand if you see it work -- just open studio with nothing but a plane and a sphere, apply the IES based material to the sphere and start the Fire render engine(set environment to none)... as you move and rotate the sphere the material travels with it -- just like any other material you would map onto an object.

Best,
Jason.

[Tim Ellis]

The sphere is best suited as an object for IES data file illumination. Some IES data files have light that goes upwards, some downwards & some both ways. If you used a circle then the flat geometry wouldn't create the light correctly.

In Studio, the object's pivot axis is displayed in the viewport. Therefore you have a visible means to tell which way is up. Translate, rotate & scale all have handles that are displayed for a selected object in the view port, which aid you to align IES objects correctly.
The IES data is also visually displayed in the Studio viewport, by means of a blue lattice which matches the shape of the IES file.

If you wish to use Rhino, there may be a method to display the sphere's pivot but I'm not sure.

Important note: IES and Eulumdat files are commonly used to mimic lighting fixtures, using the lighting information files provided by manufacturers. They are handy because they can easily imitate the complex lighting effects produced by certain specific fixtures, without having to model the lamp itself. However, they must be used with care because they can sometimes produce physically incorrect results.
Both formats contain the luminous intensity at any angle, measured in laboratory using light sensors located all over a spherical dome around the light source, pointing to the center of the dome so that the data capture method considers all lamps as point sources. This means that with these formats, the physical correctness of the result is highly dependent on the geometry you apply the IES/ Eulumdat files to.
To get the most physically correct results, IES/ Eulumdat files should be applied to small spheres to copy the laboratory environment they were measured in as much as possible. Applying an IES or Eulumdat file to a geometry other than a small sphere or using files captured from a non-point lamp can cause inaccuracies inherent to the method and format definition.

Tim.