LuxRender lighting assistance

AJ2112

Hi friends, I've recently began learning the basics of LuxRender. Was wondering what is causing lights to reveal on surfaces, opposed to surfaces being solid. I tweaked everything in DS and Lux surfaces tab, still same thing.

Another example, I'll create a primitive sphere, no lights, Lux will render with a bright light in center of sphere.

Also what are Mesh lighting ? How do I create a mesh light.

Thanx for assistance. .

Toyen

Hey there! I´m no expert when it comes to Lux Render, I only tried it once in Blender and i don´t have the reality plugins but, from the picture it looks like as if there was a plane mesh emitting light in the scene.
Maybe when you do not add any lights in the scene, Lux render throws in a plane emitter that serves as some kind of default lighting setup.

And if you do have a mesh that serves as an emitter, whether it will show on an object´s surface depends on the reflection settings I guess. The sphere is shiny any reflects light.

Also another way to get a reflection on a mesh surface is if the mesh has a reflection map I guess which I doubt this sphere has.

But, I could be wrong, I´m no expert : )

StratDragon

the reflection is the light pane or other geometry you are using reflecting against a glossy surface

you can move the lights, adjust the size of the pane (which will alter the physics of the light) or make the surface less glossy or matte.

the reason this is happening is it would happen in real life, a square emitting light would reflect as a square over a reflective surface in it's path.

if you are using LuxRender though Reality you could also try to use the reality lights by Callad.
http://www.sharecg.com/v/68284/related/21/daz-studio/reality-light-system-for-ds-+-reality-+-luxrender
which offer circular light emitters as opposed to square ones.

Mattymanx

How are you exporting your scene to Lux Render?

StratDragon

I know in Blender you will get a blank render without some light source in your scene if you try to render internally with LuxRender and it wont even kick of the external engine (LuxRender) until you add some sort of light source.

I made a sphere with a high gloss shader (car paint) and a torus with glass. in the upper left hand corner is a primitive pane that is converted to a light emitter. Both surfaces (the sphere and the torus) are reflecting that object.

another possibility is an IBL HDR image is being used a as light and the image contains a bright surface in which case I don't think there is a way to remove the reflections.

Herald of Fire

If you are using Luxus to export and try to render without a light source, Luxus creates one for you similar to the headlamp default in DS. That's the source of the glare in your second example.

Szark

To Create Mesh light.

I will assume you have placed a mesh in the scene inside Daz Studio, it can be anything as we aren't limited to what meshes we use in Lux like we are in DS. Select the mesh, go to the Surfaces Pane in DS and click on the Options Box at the top right/left corner and click on Luxus _ Luxrender Material and then choose Null in the Material Type and click the Light Parameters check box > click Accept

Next in the Surfaces Pane scroll down to the bottom and turn ON Luxrender Light Enable, you can give it a colour if you want but you can do that in the Luxrender console. Plus if you are using Linear rendering then no need to worry about the wattage as again you can adjust the intensity while you are render in Linear mode. Wattage setting is for Non Linear rendering.

AJ2112

Thanks for helpful information dear friends. I am using DS Lux plugin. Discovered LuxRender works very different then DS. What's causing the reflection is area light. Just did a quick render. In 3Delight area light is not visible, in LuxRender it is.

I'm using Spheric labs default Areal Light & Sky 2. Turn off area light, reflection disappears.

Sun & Sky 2 Daylight reflects the sun on sphere. When I move the sun behind the sphere render is blank. Oh goodness, more render experiments, Lol !!!

AJ2112

Hi Herald, thanx for input. Figuring out LuxRender is very different then DS. When I try to use DS or AoA lights, I get a white spot on a blank canvas. LuxRender is a whole different lighting system.

HeraldOfFire said:

If you are using Luxus to export and try to render without a light source, Luxus creates one for you similar to the headlamp default in DS. That's the source of the glare in your second example.

AJ2112

Hi Pete, thanx for input friend. I have no idea what Mesh light is or how to create ? I tried using a reality mesh light suggested by Stratdragon, Lux renders a blank canvas with white spot. I get those alot, Lol !!!! Sphere illuminates in DS preview, but not render. Wow ! this is going to be a brain twister, Lol !!!! Just put a table under sphere, it works. Awesome ! making progress !. Now I get light needs to reflect off surface to illuminate object.

This is going to be fun :bug:

Szark said:

To Create Mesh light.

I will assume you have placed a mesh in the scene inside Daz Studio, it can be anything as we aren't limited to what meshes we use in Lux like we are in DS. Select the mesh, go to the Surfaces Pane in DS and click on the Options Box at the top right/left corner and click on Luxus _ Luxrender Material and then choose Null in the Material Type and click the Light Parameters check box > click Accept

Next in the Surfaces Pane scroll down to the bottom and turn ON Luxrender Light Enable, you can give it a colour if you want but you can do that in the Luxrender console. Plus if you are using Linear rendering then no need to worry about the wattage as again you can adjust the intensity while you are render in Linear mode. Wattage setting is for Non Linear rendering.

Herald of Fire

A mesh light is as the name implies. It's a mesh which acts as a light source. The mesh itself can be anything. A sphere, a plane, even more intricate shapes such as a light bulb. The amount of light it provides is divided up amongst its surface. So, the more surface area the light has, the dimmer and softer the light will be overall. A small square will provide a very intense light while the same square scaled upwards will provide a softer glow since it now has a bigger area to work with.

Once you get your head around the idea that Luxus light behaves like real world light, it becomes a lot easier to understand and work with. I'm far from being an expert myself, and there's always something new to learn. But then, learning is half of the fun, isn't it?

StratDragon

Heres the Blender scene with the camera pulled back, the 3 flat planes which are simply 3d models and set to their surfaces are emitting light. (note the grease pencil marks I added by hand that look like a 4 year old made them) I could in effect use any shape for a light but for the simplicity of speed I use a flat plane. The plane will only show light from the side with the normals (faces) that point out from the surface of a the model (the faces on the back will point back into the front face and no light will be visible from it.)
I can change the intensity and power of these lights and in the render they would react to those changes. If I change the shape or the size of the panes they will also react as they would in real life. A smaller light with the same power will be more intense in some areas and less overall than a bigger light and the shadows will become sharper, a bigger plane at the same intensity will distribute less light to a specific area because it's spreading the same amount of power over a larger area, it will also produce softer shadows.
3Delight is a biased rendering engine so you can actually tell a light in 3Delight not to cast a shadow, this can't be done in real life and LuxRender calculates light as it's done in nature so 1) the light has to come from something and 2) it has to cast a shadow when it's blocked by a solid object. The two engines are very different and it's hard to compare them from how they behave.

BTW if you use Luxus the Reality lights wont work but you can probably create another shape to make a light like I did in Blender, and if you are doing an outdoor scene you can generally make a single light that acts like the sun and takes care of all your global lighting. In Reality you just make a infinite light and name it "Sun" and point it like a camera, but I don't know how Luxus does it.

AJ2112

Pete, thanx a million. Works like a charm. Question, in DS surface tab or Lux Tone mapping - Linear, how do I decrease the lights illumination ? Light is super bright. It's like DS surface tab doesn't work for Luxus renders.

Szark said:

To Create Mesh light. Next in the Surfaces Pane scroll down to the bottom and turn ON Luxrender Light Enable, you can give it a colour if you want but you can do that in the Luxrender console. Plus if you are using Linear rendering then no need to worry about the wattage as again you can adjust the intensity while you are render in Linear mode. Wattage setting is for Non Linear rendering.

AJ2112

Hi Stratdragon, I rarely use Blender, so unfamiliar with software program. Thanx for all the helpful info you provided, will try similar method in DS. Reality light's work with DS LuxRender plug in.

StratDragon said:

Heres the Blender scene with the camera pulled back, the 3 flat planes which are simply 3d models and set to their surfaces are emitting light. (note the grease pencil marks I added by hand that look like a 4 year old made them) I could in effect use any shape for a light but for the simplicity of speed I use a flat plane. The plane will only show light from the side with the normals (faces) that point out from the surface of a the model (the faces on the back will point back into the front face and no light will be visible from it.)

I can change the intensity and power of these lights and in the render they would react to those changes. If I change the shape or the size of the panes they will also react as they would in real life. A smaller light with the same power will be more intense in some areas and less overall than a bigger light and the shadows will become sharper, a bigger plane at the same intensity will distribute less light to a specific area because it's spreading the same amount of power over a larger area, it will also produce softer shadows.
3Delight is a biased rendering engine so you can actually tell a light in 3Delight not to cast a shadow, this can't be done in real life and LuxRender calculates light as it's done in nature so 1) the light has to come from something and 2) it has to cast a shadow when it's blocked by a solid object. The two engines are very different and it's hard to compare them from how they behave.

BTW if you use Luxus the Reality lights wont work but you can probably create another shape to make a light like I did in Blender, and if you are doing an outdoor scene you can generally make a single light that acts like the sun and takes care of all your global lighting. In Reality you just make a infinite light and name it "Sun" and point it like a camera, but I don't know how Luxus does it.

AJ2112

Hi Herald, thanx for mesh light info. LuxRender lighting is challenging, tricky but fun to learn. I'm trying to create a lamplight, but the illumination is intense !!! Can't figure out how to decrease illumination, I'm making steady progress, the more I learn, the more I'm consumed with 3D, Lol !!! Just started learning LuxRender this week, quite surprised/happy with results. Thanx for all your help/support.

HeraldOfFire said:

A mesh light is as the name implies. It's a mesh which acts as a light source. The mesh itself can be anything. A sphere, a plane, even more intricate shapes such as a light bulb. The amount of light it provides is divided up amongst its surface. So, the more surface area the light has, the dimmer and softer the light will be overall. A small square will provide a very intense light while the same square scaled upwards will provide a softer glow since it now has a bigger area to work with.

Once you get your head around the idea that Luxus light behaves like real world light, it becomes a lot easier to understand and work with. I'm far from being an expert myself, and there's always something new to learn. But then, learning is half of the fun, isn't it?

Szark

awesomefb said:

Pete, thanx a million. Works like a charm. Question, in DS surface tab or Lux Tone mapping - Linear, how do I decrease the lights illumination ? Light is super bright. It's like DS surface tab doesn't work for Luxus renders.

Szark said:

To Create Mesh light. Next in the Surfaces Pane scroll down to the bottom and turn ON Luxrender Light Enable, you can give it a colour if you want but you can do that in the Luxrender console. Plus if you are using Linear rendering then no need to worry about the wattage as again you can adjust the intensity while you are render in Linear mode. Wattage setting is for Non Linear rendering.

First how are you rendering? Inside DS or using the Lux Console as if you use DS then you will not have any control over adjusting the light on the fly. That can only be done via the Lux Console when you set Luxrender to Linear for Tone Mapping Kernel in the Render Settings Pane or in the Lux Console after hitting the render button.

If you want to use Non Linear then you need to set the Wattage of the light in the Luxus Surface setting in the Surfaces Pane.

Szark

Hopefully this will help better

AJ2112

Hi Pete, I am using Lux console. My brain is overworked, Lol !!!! Workin like a charm. Thanx bud ;-P: I was experimenting with light groups most of the evening, didn't pay much attention to primitive area light, only what was illuminating. I've discovered lighting in Lux is much more challenging then DS. With LuxRender an individual has to build a lighting system. I also read not to use DS spotlights/pointlights Luxus manual, been experimenting with spotlights, appears to work fine for smaller areas. Plan on illuminating a room over the weekend. Then read up on tweaking materials, maps, etc.... for LuxRender. You have a super wonderful weekend bud :coolsmile:

Szark said:

awesomefb said:

Pete, thanx a million. Works like a charm. Question, in DS surface tab or Lux Tone mapping - Linear, how do I decrease the lights illumination ? Light is super bright. It's like DS surface tab doesn't work for Luxus renders.

Szark said:

To Create Mesh light. Next in the Surfaces Pane scroll down to the bottom and turn ON Luxrender Light Enable, you can give it a colour if you want but you can do that in the Luxrender console. Plus if you are using Linear rendering then no need to worry about the wattage as again you can adjust the intensity while you are render in Linear mode. Wattage setting is for Non Linear rendering.

First how are you rendering? Inside DS or using the Lux Console as if you use DS then you will not have any control over adjusting the light on the fly. That can only be done via the Lux Console when you set Luxrender to Linear for Tone Mapping Kernel in the Render Settings Pane or in the Lux Console after hitting the render button.

If you want to use Non Linear then you need to set the Wattage of the light in the Luxus Surface setting in the Surfaces Pane.

Szark

LOL I wouldn't say more challenging, I would say different that is all. You don't need to fake many things in Lux/Blender Cycles or Octane as you would do in DS. So in some ways it is easier. And though these render engines are physically based on reality we still need to fake a few things to get better and quicker results.

For example for indoor scene with a Sun shinning through a window one might think that in these physically based engines that would be all you need and up to a point if the materials are set up correct you could in theory let it render for a few weeks and you might get a good result.

Best to throw in an additional light source to speed things up a bit. Yes Spots light aren't practically good in many of the render engines. Points, Distant, HDRI and Area (Mesh) lights. Don't forget you can turn a simple plane area light into a realistic light source by using IES File (https://www.google.co.uk/?gws_rd=cr&ei=1eHaUuqrI-i6yAPd2IDQDg#q=what+are+ies+files)

Yeah you have a great weekend too dude.