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LED Screen Light Emision

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How do I make an LED screen actually emit light in renders?

 

It seems to not have any back luminance emitting from the screen in "REALISTIC SPOTLIGHT" renders. This seems to be true for television screens and projection screens as well. 

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The texture should have a Glow shader. It's typically at 100% but can be set higher. Too high and the image will blow out.  Emit Light should be checked in both eh edit Shader dialog and in the Indirect Lighting dialog.

 

You won't get any beams of light, but you should get the effect of light.

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On 1/8/2021 at 11:18 AM, Kevin Allen said:

The texture should have a Glow shader. It's typically at 100% but can be set higher. Too high and the image will blow out.  Emit Light should be checked in both eh edit Shader dialog and in the Indirect Lighting dialog.

 

You won't get any beams of light, but you should get the effect of light.

Which brings up another question: how is that output actually calculated?  I tend to find that I cannot get enough light out of a display to render realistically before the image blows out. 
 

As I am writing this it occurs to me that perhaps I should let the image blow out quite a bit. What I will try is duplicating the texture with one completely blown out and the second at a normal intensity, however, set the second not to create shadows. Then I place the blown out image on my screen PIO, create a simple piece of geometry in front of the screen and map the second texture there. That should give you the best of both worlds. I’ll give it a shot when I have a minute. 

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51 minutes ago, scottmoore said:

Which brings up another question: how is that output actually calculated?  I tend to find that I cannot get enough light out of a display to render realistically before the image blows out. 
 

As I am writing this it occurs to me that perhaps I should let the image blow out quite a bit. What I will try is duplicating the texture with one completely blown out and the second at a normal intensity, however, set the second not to create shadows. Then I place the blown out image on my screen PIO, create a simple piece of geometry in front of the screen and map the second texture there. That should give you the best of both worlds. I’ll give it a shot when I have a minute. 

Following with interest

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3 hours ago, scottmoore said:

Which brings up another question: how is that output actually calculated?  I tend to find that I cannot get enough light out of a display to render realistically before the image blows out. 

 

That's a really good question. I've neither seen nor figured out any documentation on this kind of thing.

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I tried it. Didn’t work. Since the glow texture emitting light is not actually a light source that VWX recognizes, it does not penetrate through a piece of geometry that includes a texture that does not cast or receive shadows. Kind of a drag as that would have been a useful tidbit.  You can certainly put a light object behind that texture but getting the shape of the light source correct would be a nightmare. 
 

 

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On 1/8/2021 at 9:27 AM, Pochflyboy said:

How do I make an LED screen actually emit light in renders?

 

It seems to not have any back luminance emitting from the screen in "REALISTIC SPOTLIGHT" renders. This seems to be true for television screens and projection screens as well. 

Also note, if you want to actually see the glow you will need to a) enable indirect lighting, which incidentally is true of any glow texture that emits light, and b) you will need at least one other light source in the drawing so that you can turn the VWX ambient light off. For instance, if you just want an LED wall to illuminate your scene, you will need to turn off ambient light and place a light object with an intensity of 1% and possibly even give it a dark gray color. The light object will effectively be “off” but VWX won’t know that.  If you have no legitimate light object in the scene, VWX will turn on the ambient light by default. 

Edited by scottmoore
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8 minutes ago, scottmoore said:

Also note, if you want to actually see the glow you will need to a) enable indirect lighting, which incidentally is true of any glow texture that emits light, and b) you will need at least one other light source in the drawing so that you can turn the VWX ambient light off. For instance, if you just want an LED wall to illuminate your scene, you will need to turn off ambient light and place a light object with an intensity of 1% and possibly even give it a dark gray color. The light object will effectively be “off” but VWX won’t know that.  If you have no legitimate light object in the scene, VWX will turn on the ambient light by default. 

@scottmooreThanks for those tips.

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A few examples depicting light emitting displays.  The room in which this display is placed is 100' x 100' x100' and just uses white as a finish.  Another note is that the screen tool applies the texture to BOTH SIDES of the face so if you want to block the back side from being visible or emitting light you need to make the base structure the same size as the modules.  Likewise, in the example where I included simple geometry to create a screen, you would also need a blackout piece of geometry in the back.  In this case, it would also NOT cast shadows.  

100%.png

125%.png

250%.png

geo w:lxsource.png

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13 minutes ago, scottmoore said:

A few examples depicting light emitting displays.  The room in which this display is placed is 100' x 100' x100' and just uses white as a finish.  Another note is that the screen tool applies the texture to BOTH SIDES of the face so if you want to block the back side from being visible or emitting light you need to make the base structure the same size as the modules.  Likewise, in the example where I included simple geometry to create a screen, you would also need a blackout piece of geometry in the back.  In this case, it would also NOT cast shadows.  

100%.png

125%.png

250%.png

geo w:lxsource.png

Ty @scottmoore Did you need to edit the base image?

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9 hours ago, mjm said:

Ty @scottmoore Did you need to edit the base image?

No. As you can see, at 250% the image gets quite blown out. I generally find that I can’t go much over 125%-135% before the image becomes unusable. Of course, that also depends on the image. 

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15 hours ago, scottmoore said:

No. As you can see, at 250% the image gets quite blown out. I generally find that I can’t go much over 125%-135% before the image becomes unusable. Of course, that also depends on the image. 

Looks pretty dang good at 125%

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125% is generally my default. My opinion is that most LED displays will emit more light than that even when the NIT level is dialed back. I often help things out a bit by adding an “ambient” light or two to a render. 

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For a quick hack: I would render it out with the texture blowing out to what ever lights the room correctly and then overlay clean artwork on the screen in post (Photoshop). 

Edited by EAlexander

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12 hours ago, EAlexander said:

For a quick hack: I would render it out with the texture blowing out to what ever lights the room correctly and then overlay clean artwork in post (Photoshop). 

I would agree with that. 

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