Translucent Lampshade

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Permalink Reply by Render Plus on May 28, 2013 at 1:43pm

It sounds like you want to see the lamp inside the lantern, so translucent (shade) will not be the solution.

Can you make a small sample model for us - probably a single shade and light source, and also an image from somewhere of what we are trying to achieve.

Post both here, and I will take a look or we can try to get help elsewhere.

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Permalink Reply by Render Plus on May 28, 2013 at 2:35pm

We need to see if anyone has experience with this. I will post the question on the AutoCAD nXtRender forum as well.

http://www.accurender.com/forum/topics/lamp-shades

Mostly, we just need to play with things.

One things to make things faster is to use a smaller render size (here I used 400 pixels wide) and just a few passes (I used 4) to make it easier to test various settings.

Here are 4 samples.

(I uploaded the simple model I used if anyone wants to help show us how to do this)

1. Material Color 255,0,0 transparency 25%

Here I reduced the transparency to 10%

Then I added a 5% self glow:

Then I lowered the color itself to 128,0,0

Attachments:

• shade_test.skp, 86 KB

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Permalink Reply by Render Plus on May 29, 2013 at 7:07am

From the images you sent, I suspect you are looking for a look kind of like this:

Note, that although the light is visible - it is not fully visible (you cannot see the detail of the bulb - just brighter areas where the bulb illuminates the shade), so a translucent shade effect may work.

I will add more about using translucency in the next post/

 

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Permalink Reply by Render Plus on May 29, 2013 at 7:15am

Transparency Adjustments

In working with this, I found a number of things which make it difficult to work with translucent lamp shades.

We have two default settings which were supposed to make it easier to work with transparency when rendering SketchUp models, but which make it harder to get the effect you want with dark colored transparent objects.

1 SketchUp OpenGL treats transparent colored objects differently than IRender nXt. In particular nXt never lets light through an object, not matter how transparent, if the color is not contained in the object. So a pure Red filter will never let blue or green colors be seen through it. SketchUp does not work this way, if you make a pure red object transparent, other colors will show through it. So pure-black glass in SketchUp will let other colors through, but pure black glass in IRender nXt will never let any light through no matter how transparent it is.

We added a setting to add some "white" to pure transparent colors to make IRender nXt render transparent objects more like they appear in SketchUp.

2. IRender nXt was getting a different level of transparency than SketchUp.

 So we added a feature to adjust the transparency when rendering so things would render more like they appeared in SketchUp.

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To try to get a specific transparent effect, you will need to turn these two adjustments off.

This can be done on the support dialog - available from the "More" tab of the options dialog.

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Permalink Reply by Render Plus on May 29, 2013 at 7:43am

After turning off those two settings, I was able to get something which might work.

But it is very tricky to get translucency just right.

Also, it is tricky to work on just a single light, so I added a second light to get an effect closer to what will happen when you do this in a model.

For this rendering I made the lamp shade pure red (255,0,0), set thransparency to 1.00 and translucency to 0.10

If you adjust these, then the shade quickly becomes purely translucent.

e.g. in this rendering I set transparency to 0.90 and translucency to 0.10

The shade is translucent, but you cannot see the effect of the bulb at all.

Here I used transparency = 0.97, and translucency at 0.03 and you can just barely see the bulb.

Perhaps this will work for you.

Note: with a black shade, you will have to make it at least a little grey (e.g. RGB: 5,5,5) to let some light through.

Here is a black shade with RGB 5,5,5 transparency 0.80 and translucency 0.90

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