Confusion between light channel in object property and IRender Lamp

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Permalink Reply by Render Plus on October 17, 2011 at 8:09am

IRender Lamps and Object Property Lamps are two different ways to make lights. They are not the same.

If you place an IRender Lamp it places the lighting properties as SketchUp attributes on the lamp component.

If you have your own gemoetry or your own component and want to treat it as a light, then you will use Object Properties.

But you don't want to try to use both on the same geometry, or on the same component.

I know this can be confusing. But each of or way to create lamps has it uses. For example, it is very easy to place an IRender Ceiling Light on the ceiling, or to place an IRender light bulb into a lamp fixture. However, if you have a lamp fixture which already has geometry in it for the lamp, bulb, or light source, then it makes more sense to turn that geometry into an Object Property lamp, then to try to replace it with an Irender lamp.

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Permalink Reply by Alain Bonnefoy on October 17, 2011 at 10:20am

In fact I want to talk about iRender lamp (IR_lamp_linear_glow_75W_17.72x1.575X1_#ffffae.skp) and in that case, it seems the channel value, set by the iRender lamp dialog, is not taken in account by the rendering engine.

It's the reason why I had to set the right channel number also in the Object property dialog for the iRender lamp object. I suppose irender engine should have a look on both light channel field ( and in that case, what is the correct one,do you understand?) or iRender lamp dialog should also copy the value in Object property's light channel field.

I just so this problem in linear lamp, I didn't verify if other irender lamp objects have the same problem or not.

 

 

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Permalink Reply by Render Plus on October 17, 2011 at 10:59am

IRender nXt lamps have the Channel set to 0 - which means to use the default channel which is set on the lighting setup tab - 3 for ceiling lights, 2for all other lights.

Object Property lights have a Channel of 0 which means use the default channel - 2 - other lights.

Another thing for lighting channels is that you need to enable more than one channel on the lighting setup tab. We do not automatically enable all channels because it slows down the rendering process and takes up more RAM memory to use lighting channels.

Also, there is a "hard" limit of 8 channels, so we cannot really decide how the users should use them. We assign one for sun and one for sky (some people assign a single channel for both sun and sky, or for an interior you could use those two channels for other lighting groups). We also assign channels for ceiling light, other lights and self glow materials (such as TV screens). That means we have per-assigned 5 of the 8 channels and only left 3 more for the user.

Each use needs to decide what he/she wants to use channels for, and assign them as needed. You could use one light channel setting to balance the lights in one part of the rendering - then change the individual lights based on that you learned from the lighting channels, and then reuse the same lighting channels to balance lights in another part of the rendering.

It is unfortunate that we cannot simply assign a different channel to each light, and perhaps in a few years when we all have 1,000 GB RAM instead of 4GB, and much faster processors this will become a reality. But for now, you have to "pick and choose" how you want to use the lighting channels.

 

 

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Permalink Reply by Alain Bonnefoy on October 18, 2011 at 2:05am

I have no problem with all these things Al, I just wonder why setting a channel for a iRender Lamp with the iRender Lamp dialog box seems to not set anything and why we have to set it with the Object property instead.

But in fact, in my case, if Object properties' light channel was set to 2 means that I personnaly set this value.

In that case, I suppose it means that Object properties' value has priority on the one set by the iRender Lamp dialog box.

So here is the confusion. I just wonder if it would be possible to decide that the iRender Lamp dialog box is maybe not really indispensable as it concerns intensity and channel which already are in the Object properties dialog box. These 2 fields can have different value in each of them and in that case, we don't really know which one is used by the rendering engine.

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Permalink Reply by Render Plus on October 18, 2011 at 7:23am

Part of the confusion here is that you should not need to use the Object Properties dialog to set intensities or channels for an IRender lamp. I think we should remove the object properties wizard as a choice for IRender lamps. There isn't anything on there that shoud be used for a lamp, except invisible. Sometimes you may want an invisible lamp - which casts light but cannot be seen.

 

Here is a scene I just created, all the lights except the sconce are IRender nXt lamps with default lighting channels settings. For the sconce, which came from the 3D warehouse, I drilled in until the white lens was visible and made it an omnidirectional light source in channel 4.

 

The socnce is too bright, so I then loaded lighting channels and lowered the intensity of the sconce from 1.0 to 0.1

Auto-illumination then made the other lights brighter.

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Permalink Reply by Alain Bonnefoy on October 18, 2011 at 7:40am

I think we should remove the object properties wizard as a choice for IRender lamps.

Yes, I think something like that could be done.

Thanks

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Permalink Reply by Render Plus on October 19, 2011 at 6:51am

We have removed Object Properties as a right-click choice for IRender lamps.

The only setting for Object Properties which may have been useful was "invisible". Which would have made the lamp invisible, while still letting it cast light. There is a similar setting already on the "Edit IRender Lamp" right click called "Hide this lamp when rendering"

We will try to get a new version out today - because there are some other right-click items not showing up properly for objects without materials.

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Permalink Reply by Alain Bonnefoy on October 19, 2011 at 8:21am

no problem Al

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Permalink Reply by Alain Bonnefoy on October 19, 2011 at 9:12am

Please take care that iRender Lamp dialog set the channel field because I tried to set it for one of the bedside lamp (Rendering a bit strange on white surface thread) and it doesn't set anything. I had to use object properties instead.

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