Bad IES file

[YoyoBoy]

I am doing an animation to show off the properties of a new product from a lighting company. The IES file they sent seems very low resolution, and the spot that it projects has a noise to it that resembles heavy JPEG artifacts. I've tried it with both the VRay IES light as well as the Max IES with scanline, and get the same result.

Another funny thing is that the representation of the beam points in a very different direction from the VRay light. It renders in the light's direction at rendertime, but in the viewport it renders in the direction of the beam icon. When using a Max light with scanline it renders both in the icon direction.

I would love to post the IES file, but I have been asked not to.

Does anyone have experience correcting these sorts pf issues? Should I just ask the company for a better quality IES file?

Thanks!

[alexyork]

You could always recreate it using IES Generator or similar.

[YoyoBoy]

Update: I emailed an expert on these things and he said that it isn't working right because it is a "Type A" IES file, and Max and VRay only open Type C.

[alexyork]

Interesting problem.

[trixian]

Ah. Good thing we don't have standards.....

What is the difference between these Type A,B,C IES formats?
What programs read Type A?

[YoyoBoy]

Here's a description: http://www.agi32.com/kb/index.php?article=432

The guy I contacted is the author of this IES software and he told me: "Types A and B are mainly used in the calculation programs. Type C is the most versatile so it's best to use it."

[YoyoBoy]

Actually, maybe that page isn't describing IES files. Hmm... having trouble finding clear info on that.

[YoyoBoy]

I've only partially solved this issue, but in general I'm a little confused about IES light and the way to use them. The projection comes from a single infinitely small point, but actual the light itself is an array of LEDs about 15x5 cm. Am I supposed to check "Override Shape" and make it fit that? Will that screw up the projection at all?

Thanks.