Texture Emission

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Texture Emission

Postby Angelos » Fri May 06, 2016 12:07 pm

Angelos Fri May 06, 2016 12:07 pm
I have hdr image of real photographic lights and would like to map it on grid objects.
In 3dsmax it's quite simple to do:
Image
Diffuse material > Texture Emission > RGB Texture image

But how to load RGB Texture image in Diffuse material in Houdini?
Image


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Re: Texture Emission

Postby juanjgon » Fri May 06, 2016 1:01 pm

juanjgon Fri May 06, 2016 1:01 pm
You only need to add a texture image node linked to the 'efficiency' emission input.

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Re: Texture Emission

Postby Angelos » Fri May 06, 2016 1:12 pm

Angelos Fri May 06, 2016 1:12 pm
I treid to put in your way but it doesn't work for me.

Seems it's work in this way:
Image

Version 2.25.0.1
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Re: Texture Emission

Postby juanjgon » Fri May 06, 2016 1:15 pm

juanjgon Fri May 06, 2016 1:15 pm
Hmmm, true. This should work also. I am not sure about what is the difference, perhaps something related to the support of the projection nodes ... if it works now, go ahead ;)

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Re: Texture Emission

Postby Angelos » Fri May 06, 2016 1:30 pm

Angelos Fri May 06, 2016 1:30 pm
I also tried to map it as object properties on each grid object:
Image

It seems to work but I get these strange map distortions:
Image
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Re: Texture Emission

Postby juanjgon » Fri May 06, 2016 1:37 pm

juanjgon Fri May 06, 2016 1:37 pm
You are right, this is an old issue that I must fix. The texture mapping in the Object Properties is designed to support only IES files. I has a projection node to map the IES in the geometry, so it has always a fixed projection and doesn't support the object UV map. I need to add an option to select if you are using an IES light or a UV texture map.

Currently you must use the emission material to work with textured emitters.

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Re: Texture Emission

Postby Angelos » Fri May 06, 2016 2:21 pm

Angelos Fri May 06, 2016 2:21 pm
If I put the texture in distribution channel I get strange UV and overbrightened colors
Image

This is what I try to get:
Correct UV's and light
Image
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Re: Texture Emission

Postby juanjgon » Fri May 06, 2016 2:50 pm

juanjgon Fri May 06, 2016 2:50 pm
But, are you mapping the HDR texture in a environment sphere? How is it mapped, with UVs?

If you are mapping the HDR texture in an obeject with an UV map, link the texture image node to the 'efficiency' input should work without problems, as you can see in the attached image. Also be aware that by default the texture image node has a 2.2 gamma correction, you should set this parameter to 1.0 for the HDR images.

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Re: Texture Emission

Postby Angelos » Fri May 06, 2016 3:26 pm

Angelos Fri May 06, 2016 3:26 pm
Just three grids with UV. Changed the gamma to 1.0 and it works correctly.
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Re: Texture Emission

Postby juanjgon » Fri May 06, 2016 3:28 pm

juanjgon Fri May 06, 2016 3:28 pm
Great! If you have more problems, please let me know ;)

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