Author Topic: Light visibility with directionality  (Read 10901 times)

2016-02-11, 09:09:19

Alessandro

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This is not really a bug, but imho an incorrect way to manage light visibility.
See attached pic, using a directionality value >0 cause the light source become invisible out of the cone of directionality. Always, when I use a visible light I need to always see it, in this moment I have to add an auto illuminated surface to be sure to see light source.
Maybe there should be a flag to define if the light source is always visible with any directionality value.
My Ducati or a render with Corona.....mmm, hard question!

2016-02-11, 09:43:54
Reply #1

romullus

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As you already figured it by yourself, it's not a bug, but correct behaviour. There is a methods how to overcome this if you don't like results. Try to search for solutions in these topics: https://forum.corona-renderer.com/index.php/topic,6542.0.html and https://forum.corona-renderer.com/index.php/topic,6539.0.html
I'm not Corona Team member. Everything i say, is my personal opinion only.
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2016-02-11, 10:33:14
Reply #2

Alessandro

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Yes, exactly as I'm doing now. But it's a big annoy, I have to add a geometry, and move it with the light if I need to move the light, and so on...
I agree with Ondra, web described in IES file depends by a lot of value, maybe the most important is the shape of the light bulb and the shape of the "case" of the light. So, actually, if point of view is out of the web, light source is not visible.
But.
When I prepare conceptual render I often need this kind of solution. It could be very useful to have the capability to force light source visibility. And (Ondra, I apologize for the next words...) I think it is not thousand rows of codes :|||| (ok, I'm joking Ondra, don't be angry;) )


It's just me? If it's, ok, I'll go on with creating a lighted surface above the light.
My Ducati or a render with Corona.....mmm, hard question!

2016-02-11, 10:34:44
Reply #3

FrostKiwi

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This is not really a bug, but imho an incorrect way to manage light visibility.
See attached pic, using a directionality value >0 cause the light source become invisible out of the cone of directionality. Always, when I use a visible light I need to always see it, in this moment I have to add an auto illuminated surface to be sure to see light source.
Maybe there should be a flag to define if the light source is always visible with any directionality value.
Rayswitch a self illum material in direct override slot, 0% performance loss, no geometry needed.

2016-02-11, 11:42:43
Reply #4

Alessandro

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Rayswitch a self illum material in direct override slot, 0% performance loss, no geometry needed.

.. :| really, sorry, but I can't understand what you mean. Can you please explain me better what you suggest me to do?
My Ducati or a render with Corona.....mmm, hard question!

2016-02-11, 14:19:43
Reply #5

FrostKiwi

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.. :| really, sorry, but I can't understand what you mean. Can you please explain me better what you suggest me to do?
The cheap solution is to apply the Corona RaySwitcher Material to the Light. I presume your light is a cricle, so get a small circle/disk and apply it. In all the slots you put a corona light mtl with the same settings as the light. At this point you have the light casting like it did before, nothing change, same look, same performance. now you apply to the direct ovveride, reflection and refraction the same lightmtl, but with 0 directionality.

What you get is a light that looks like a 0 directionality light, you see it from every angle, in reflections and refractions as well, but the light itself casts a directional light.

2016-02-11, 15:10:36
Reply #6

Alessandro

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.. :| really, sorry, but I can't understand what you mean. Can you please explain me better what you suggest me to do?
The cheap solution is to apply the Corona RaySwitcher Material to the Light. I presume your light is a cricle, so get a small circle/disk and apply it. In all the slots you put a corona light mtl with the same settings as the light. At this point you have the light casting like it did before, nothing change, same look, same performance. now you apply to the direct ovveride, reflection and refraction the same lightmtl, but with 0 directionality.

What you get is a light that looks like a 0 directionality light, you see it from every angle, in reflections and refractions as well, but the light itself casts a directional light.

Thx for your long explanation, actually I was talking about a Light object, so I couldn't understand you ;)
It's all right for a surface with light material, your way works fine.
Best.
My Ducati or a render with Corona.....mmm, hard question!

2016-02-11, 23:42:58
Reply #7

FrostKiwi

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Thx for your long explanation, actually I was talking about a Light object, so I couldn't understand you ;)
It's all right for a surface with light material, your way works fine.
Best.
Light Object and Light MTL applied to the same material are the same thing. There is no difference between CoronaLight and CoronaLight MTL, except user interface.

2016-02-12, 09:45:45
Reply #8

Alessandro

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Light Object and Light MTL applied to the same material are the same thing. There is no difference between CoronaLight and CoronaLight MTL, except user interface.
Yes. And I find more usable light object interface than lighted surfaces for a lot of reasons.
My Ducati or a render with Corona.....mmm, hard question!

2016-02-12, 19:28:11
Reply #9

agentdark45

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Light Object and Light MTL applied to the same material are the same thing. There is no difference between CoronaLight and CoronaLight MTL, except user interface.
Yes. And I find more usable light object interface than lighted surfaces for a lot of reasons.

This.

I don't think anyone wants directional lights being dimmed no matter how physically correct the behavior may be. It would be nice to keep the light fully illuminated for all directional values as the default setting and then maybe have a tick box for those who want their directional lights to turn black.
Vray who?

2016-02-14, 12:16:33
Reply #10

karnak

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In real photography, when you want to create directional lighting, you apply for example a grid modifier to your light source.

Something like this:


When you look this light source from the side, you will see only black, because of the modifier.


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2016-02-14, 13:20:17
Reply #11

Alessandro

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In real photography, when you want to create directional lighting, you apply for example a grid modifier to your light source.

Something like this:


When you look this light source from the side, you will see only black, because of the modifier.




Of course it's true, but we can go over this kind of limits with render, why not?
As I've already say, often, most of all in conceptual renders, it's so usefull to see source place of a light, no matter its dirtectionality. I'm not talking about phisical or not phisical correct, I'm talking about having the best result with the minimal work.
And it seems I'm not alone in this .. ;)
My Ducati or a render with Corona.....mmm, hard question!

2016-02-16, 11:37:13
Reply #12

FrostKiwi

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I'm talking about having the best result with the minimal work.
And it seems I'm not alone in this .. ;)
No you are not. Need physically correct directional light?
Do nothing.
Need did rectional light to be visible from all angles?
Sacrifice 5 seconds, rightclick rayswitcher and apply to GI, copy material with 0 directionallity to direct override.

2016-02-16, 12:29:41
Reply #13

Alessandro

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I'm talking about having the best result with the minimal work.
And it seems I'm not alone in this .. ;)
No you are not. Need physically correct directional light?
Do nothing.
Need did rectional light to be visible from all angles?
Sacrifice 5 seconds, rightclick rayswitcher and apply to GI, copy material with 0 directionallity to direct override.

Of course, my dear (maybe young?) friend. But, this is your opinion. That I respect. Maybe you shoud learn to respect the other one too ;)
My Ducati or a render with Corona.....mmm, hard question!

2016-02-16, 13:30:57
Reply #14

FrostKiwi

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Of course, my dear (maybe young?) friend. But, this is your opinion. That I respect. Maybe you shoud learn to respect the other one too ;)
Didn't mean to offend you, I just fail to see the issue.

The description of the renderer states physical accuracy and eas of use as it's primary goal - anything else is faking.
The devs included an option to do exactly that.

[Directionality is usually a lamp shade thing, or a ceiling light being in a little cave from my experience, no light is just glued to the ceiling, seeing directional lights from all angles, implies the light casts rays to other directions as well, which by definition is the opposite of directionality, in archviz we aim for realism and physically accurate lighting. And again if you want it, the option is there, including it as a check box in the light modifier means including a physically wrong option, which in turn goes a bit against what archviz stands for]
And yes, I use idirectionallity + fake to see from all angles non stop, all the time, I don't do archviz, but animation, I do respect your opinion.