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I am having a number of issues with IES exposure when working with Multilight.

Issue #1.. I have setup three IES lights, controlled by one slider and started the rendering. I setup my camera to be ISO 100 and shutter of 2. When the rendering starts it appears to be converging on one solution. If I check 'Mute' on the emitters and then 'Un-Mute', the exposure intesifies greatly although none of the settings have changed. The settings are still at ISO 100 and shutter 2? What just happened? If I do the same scene, but with multi-light disabled it looks just like the initial scene before the exposure changes due to muting. I assume this is the correct solution?

This is the initial scene and preview upon pressing render.


This is the same scene, but significantly different preview and output even though no settings have changed?


This is the same IES scene above with no multi-light checked. It appears to be on the same path as the initial scene before pressing mute or changing anything.


Issue #2....Same thing happens if you use IES lights w/ skydome and multi-light. Before I touch any of the multi-light controls it appears to be on the correct exposure path. Once I change anything, the exposure for the IES lights intensifies similar to above . ??

Initial rendering...


Rendering after selecting Mute and then UnMute - Light intesifies but no settings changed!


Thanks for any help you can provide.
Paxton

Same thing happens here too!

Working on OS X Snow Leopard

Q!

I think I might know what's up. I found similar problems in using IES with multilight.

When you send a scene to render it uses the IES data but when you mute and unmute a lighting channel it sets it's intensity to 100! Normally this is 100% or 100W depending on the lighting used but in the case of IES this needs to be set right down to 1 in order to have the same value as that set in the IES data.

When you first render with multilight the slider shows 100 (as in %) but it actually should be 1 (as in IES intensity).

Easy to get around but a little confusing.

(a similar change has occurred in the Softimage plugin where environment offset values are now in degrees (i.e. 0-360) rather than, as they used to be, value (i.e. 0-1))

I am not sure this logic is correct...1 seems to be too dark and this is def. not unbiased

I would think that this feature would have been tested at this most basic level? I teach Maxwell at a local university and this version seems full of small, but significant issues it is making my job very hard.

So far..after one weekend of testing.
1. IES doesn't work with multilight correctly.
2. IES data displayed in wireframe mode (studio) has a strange relationship to geometry (the ies data should correspond to the geometry it is applied to)
3. Matte channel doesn't work (this is big, why doesn't this channel work?)
4. Shadow channel works as long as you don't have any 'black' in your texture map.
5. Viewport layouts in studo don't maintain their settings.
6. I am testing two scenarios with IES right now. One test using IES and rendering to SL15 then comparing to a test of actually modeling the light w/ a light bulb and rendering to SL15. It still has some time to render, but it looks much closer to intended light output, shape and is FASTER to just model the light versus IES. Ill post when I get back home from work.

Paxton

Yes, it seems the real intensity value is indeed 1 when using IES lights, but sliders are set to 100.
Real intensity should be 100 ofcourse.