Light emission problem

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Light emission problem

Postby mlru » Sat Aug 26, 2017 11:57 am

mlru Sat Aug 26, 2017 11:57 am
OK, this is bugging me me for quite a while now:
in the DS plugin the brightness of an emissive object is dependent on it's size and not it's energy, which is, as far as I know, not physically correct, and makes it impossible to do a physical correct scene lighting: if I want a 100W light bulb and I convert an existing mesh as emitter or place a sphere as proxy, the radiant intensity is dependent on the mesh size and not Watt value.
I made a quick comparison between Poser and DAZ (both the same scene, only the size of the emitter is changed)

Poser (scale independant, physically correct)
poser.jpg


DAZ (brightness depends on emitter mesh scale)
daz.jpg


Emitter values are in both applications and all cases the same:
light.PNG


Is there a setting I'm missing or is this a bug?
Win11/64Bit | GTX 4090 24GB | NVidia Driver 546.29 | Octane 4.05 | DAZ Studio 4.21
mlru
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Re: Light emission problem

Postby face_off » Thu Sep 07, 2017 12:57 am

face_off Thu Sep 07, 2017 12:57 am
Change the "Surface Brightness" parameter controls this.

The Octane Standalone tooltip for this parameter is
If enabled, "power" specifies the brightness of the surface and not the total emitted power, i.e. the brightness of the emitter is independent of the area of the surface
Also keep in mind that when you click the Final button, all geometry in the scene is merged into one Octane Mesh node - and this can change the brightness of emitters.

Paul
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Re: Light emission problem

Postby mlru » Fri Sep 08, 2017 9:07 am

mlru Fri Sep 08, 2017 9:07 am
Thanks, Paul, I'll have a look at this.

face_off wrote:Also keep in mind that when you click the Final button, all geometry in the scene is merged into one Octane Mesh node - and this can change the brightness of emitters.

Paul

Hm - but since the emitter gets assigned to a material zone (UV) , this shouldn't matter, right?
I'll do some tests.
Win11/64Bit | GTX 4090 24GB | NVidia Driver 546.29 | Octane 4.05 | DAZ Studio 4.21
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Re: Light emission problem

Postby face_off » Fri Sep 08, 2017 11:51 am

face_off Fri Sep 08, 2017 11:51 am
I suggest waiting for the next release of the plugin before testing, as Octane 3.07 TEST 4 has some issues when rendering with the Final button enabled.

Paul
Win7/Win10/Mavericks/Mint 17 - GTX550Ti/GT640M
Octane Plugin Support : Poser, ArchiCAD, Revit, Inventor, AutoCAD, Rhino, Modo, Nuke
Pls read before submitting a support question
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Re: Light emission problem

Postby mlru » Fri Sep 08, 2017 2:09 pm

mlru Fri Sep 08, 2017 2:09 pm
I'm cool with that :)
Win11/64Bit | GTX 4090 24GB | NVidia Driver 546.29 | Octane 4.05 | DAZ Studio 4.21
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