View Full Version : IES values

04-17-2003, 09:41 AM
My Lightwave3D will be arriving on Wednesday :) , one thing I'll need and from searching the forum, it seems is not directly supported will be the ability to use IES data.

does anyone have a table of approximations in LW's lights? and willing to share it?

apologies if this will be documented in a manual when it does arrive, I couldn't find anything on the main newtek site or this forum...

04-18-2003, 12:55 PM

Uups.... NO WAY... (forget it)...:-(



04-18-2003, 01:08 PM
I wouldn't say there is no way. You could try to find some reference values by creating a lab scene for radiosity tests, but even then it would be a major effort. Mybe next time... (version).


04-21-2003, 09:23 AM

alright! that's not the answer I was expecting, I didn't realise this was as complicated...
In Microstation I just import the values...

Mylenium, would you be able to describe the process of what you mean? I'm not shy of hard work and I'd be glad to share when I start building a decent library... as I said - approximations will get me by for the foreseeable.


04-21-2003, 09:29 AM
oops, bit of an identity crisis there ;) any way forgot to thank you guys for the responses, Thanks!

04-21-2003, 10:01 AM
Well, you could create a reference scene with some objects (walls, ceiling, floor; a red, green, blue ball etc.). If you model everything strictly to scale (you may texture everything with grids to get some idea about falloff distances) and then do some test radiosity renderings at corresponding light temperatures (using LW_ColrPckr), falloff ranges and intensities you may be able to get some idea of the corresponding IES profiles. However, this will still all be very crude and rough and may not work well enough for you.


04-21-2003, 12:27 PM
Thanks Mylenium, so just make up a cornell box, I'll look into this - obviously I need a better understanding of how the IES values are created, so I'll have to read up on that again first.

04-21-2003, 12:36 PM
Yepp, something like that. The big problem simply will be that real IES parameters are in no way linear and predictable. Keep trying, though!

Cheers, Mylenium

04-21-2003, 01:54 PM

Since I know the data structure of IES, I know you will be not able to import IES Data to LW properly.
You should consider to use other software which can import IES Data properly.

LumenMicro, Photopia or LightScape (or similar Software).

Good Luck anyway.


04-21-2003, 03:16 PM
hee hee, it's taken long enough to convince the bosses to buy Lightwave. More software? before LW has even arrived?! :D

I don't want to tell them that I can't light a scene accurately. I just need to be able to convince them that I can.

I should get away with it so long as I have intensities pretty close, I'll get away with falloffs as I'll be doing mostly outdoor scenes, and will rarely be using radiosity in the night scenes.

By the way your talking, I'm guessing that you'd need to be able to plot a curve for the light's falloff in LW? but hey - that's only a stab in the dark! (sorry).

Anyway, yeah - as I'm new to this I'm probably leading y'all in the wrong direction, if I could make a table of LW light intensities, falloff distance all with just Inverse square falloff and probably the light colour, verses a real world light type and brightness. I guess that's as close I'll need.

cheers, omeone

04-22-2003, 07:20 AM
I just found the old forum, I see Eki had a little investigation into this before, apologies for rehasing old conversations, though it does seem a lot of people are in the same boat as me...

Thanks for all the thoughts anyway guys.

04-22-2003, 07:41 AM
Now I realize that it isn't really IES values, but I think Dan Ablan has a listing of color temperatures.

You use those for aproximations.

I was talking about this awhile ago... convert from IES to actual lighting. I was thinking of taking lights off a set for color matching...

04-22-2003, 08:03 AM
Hi LW_Will, yeah IES is obviously an overkill term for what I need, I was just used to importing the IES file in Microstation, as it takes all the thinking out of setup.

I've found that in Dan Ablan's book (hadn't got that far yet), Thanks, that's exaclty the start I needed, I'll do a big search for more colour temperature values and their equivalents.

Also for 'best practice' tutes for applying this stuff, thanks again