Introduction to Maya - Rendering in Arnold
This course will look at the fundamentals of rendering in Arnold. We'll go through the different light types available, cameras, shaders, Arnold's render settings and finally how to split an image into render passes (AOV's), before we then reassemble it i
# 1 09-03-2014 , 01:30 PM
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Object_light in Mental Ray

Does anyone knows how to create mesh light in Mental Ray. I am not looking for "emit_from_surface" node because it is a way to slow to render with Final Gather. I found this article : https://elementalray.wordpress.com/20...ntal-ray-3-11/

but because I am newbie I really don't understand how to create this "buildin" node !

Can someone help me with this ?

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# 2 09-03-2014 , 08:26 PM
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He tells you how in the article. Copy and paste the declare code he posted in a normal text file, save, change the txt extension to mi and drop it in the include folder. Start Maya and make sure it's loaded and it will be in the Mental Ray shader category in Hypershade.


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# 3 10-03-2014 , 02:08 PM
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I can't compile it because I have no idea what the "transform node" is ?

"The simple workflow is:

Assign builtin_object_light material to Object -> create area light -> attach area light .message to Light parameter of builtin_object_light shader. (This picture needs updated below, you should attach the transform, not the shape)"

# 4 10-03-2014 , 04:31 PM
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The "transform" is the node that stores the object's move/scale/rotate information.


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# 5 10-03-2014 , 06:00 PM
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do you mean this one :

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# 6 10-03-2014 , 06:13 PM
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Yep, that's the one.


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# 7 11-03-2014 , 12:08 PM
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well, this was the node I did connect to the light but it doesn't work. I am not able to increase light intensity. The object does start to look as emitting light but the light is really low and no matter how much I increase it just stays at the same light intensity.

# 8 11-03-2014 , 12:09 PM
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Did you ever try this node ?

# 9 11-03-2014 , 11:42 PM
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Yes, I followed the instructions and it worked for me.
user added image


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# 10 12-03-2014 , 12:15 AM
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What is it exactly you connect from the transform node? It seems I am missing something. Sorry I am really new in working with nodes ! Does it matter the scale of the scene ? My scene is huge !

# 11 12-03-2014 , 09:20 PM
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-In Hypershade, middle click drag and drop the area light transform node onto the builtin_object_light node
-Choose "other" from the pop up menu
-When the connection editor pops up, click on the "left display" and "right display" menus on the top of the editor and make sure "show hidden" is checked on in both.
-In the left column, you should see "message" at the top of the list, click it.
-In the right column you should see "light" in the list, click it
-close the editor.


If your light is set to decay then yes the scene scale matters.


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# 12 20-02-2015 , 02:23 PM
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Sorry, i have to readopt this subject.
I try to follow the same article. (https://elementalray.wordpress.com/20...ntal-ray-3-11/)

(Assign builtin_object_light material to Object -> create area light -> attach area light .message to Light parameter of builtin_object_light shader. (This picture needs updated below, you should attach the transform, not the shape))

How to assign the Node to the Object?

Please help.

user added image


Last edited by Gallow; 20-02-2015 at 02:29 PM.
# 13 23-02-2015 , 03:12 PM
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# 14 23-02-2015 , 05:56 PM
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honestly, I don't remember how I have succeed here, give me a day to find the project and I will send you MB file with the node innit !user added image relax user added image

# 15 23-02-2015 , 07:20 PM
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You assign it just like you would any other surface shader. Middle mouse drag and drop or right click it in Hypershade and select assign to selected objects etc. I'm sure it was mentioned in the tutorial but I'll repeat it here, in the builtin light shader's shading group node, under the "custom shaders" section, uncheck "export with shading engine". Should work fine.


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