Ceiling lights wont fully render

Having trouble with my ceiling lights not fully rendering. The file has now process 255 passes and the ceiling lights look very spotty. I am using the ceiling lights to uplight a wall from the bottom in an even glow (no scalloping). I have now turned up the lights per pass to 100% and min. 100 lights per pass, but it is not doing anything different

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Permalink Reply by Rich Hart on July 13, 2010 at 12:32pm

I rendered the model that you sent Al, and it rendered OK for me. I have uploaded the rendered image after 80 passes, but it looked good after just a few passes.

I also stripped everything out except the component with the single light in it, and the floor, and rendered that. It renders OK too.

We'd like you to try the smaller stripped model to see if you get different results.
Can I just upload the stripped model here? Or would you rather I sent it to you directly?

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Permalink Reply by Bill Loomis on July 13, 2010 at 12:48pm

Rich,
When you turn down the brightness of the rendering can you see any spottiness? The renderings of the single light that I posted above looked similar to yours prior to reducing brightness. Can you post the .nxt files or your rendering?

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Permalink Reply by Bill Loomis on July 13, 2010 at 1:06pm

Rich, Al,

below are the images of the stripped down model. as you can see the as rendered image looks very similar you Rich's image. However, when I turn down the brightness to the level of light that would be visible with all of the other lights in the model, the spottiness is visible.

As Rendered;

Low Brightness;

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Permalink Reply by Rich Hart on July 13, 2010 at 1:07pm

Sorry...I hadn't noticed that you needed to turn down the brightness to see the spots.

When I do that I get them.
I'll keep looking to see if we can fix this.

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Permalink Reply by Rich Hart on July 13, 2010 at 5:16pm

We're going to add a linear light type to fix this. Below is a rendering with just the single ceiling light and another with 22 smaller ceiling lights placed end to end, both rendered for 80 passes. This is what you'll be able to do with the linear light.

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Permalink Reply by Bill Loomis on July 14, 2010 at 6:35am

Thanks guys. The linear light will be a great help. When do you think that will be added? for now I will break up the ceiling lights into multiple lights.

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Permalink Reply by Render Plus on July 14, 2010 at 7:08am

I'm working on it now.

As currently planned, it will still be a flat surface (like a ceiling light), with diffuse (one directional) light. But it will automatically be sub-divided into multiple lights.

Both the Linear light and multiple ceiling lights will take more rendering time, however they should make lights like this smoother.

Take a look at our article on Cove lights - which have a similar problem - and a similar solution (using multiple surfaces to define multiple lights)

http://www.renderplus.com/wk/Cove_Lighting_w.htm

(Cove light, above sub-ceiling - and pointing up, has been manually sub-divided into 30 separate lights - rendered for 6 passes - this needs more passes to look smoother)

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Permalink Reply by Richcat on July 14, 2010 at 9:14am

Great this will solve a few problems I have, with the test render. Never spotted the cove light before.

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Permalink Reply by Render Plus on July 14, 2010 at 2:47pm

This will be in the next version (a week or so).

See: http://irendernxt.com/forum/topics/linear-lights

A Linear Light (bottom) with 8 sub-divisions, compared to a rectangular light (top) after 20 passes.