Emitter dramatically darkens scene?....

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Russdigo
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Emitter dramatically darkens scene?....

Post by Russdigo » Sat Apr 05, 2008 3:00 am

A quick thanks to Nicholas Chapman for Indigo and SmartDen for Blendigo and all those who have supplied help and tutorials that I have browsed through before I launch into my "help me" thread.

I know my problems are something to do with Tonemapping but I've read around the issue and tried to play around with settings and violet but no luck. Actually thanks to being a Carrara and Hexagon user its been quite an up hill struggle with Blender to get to this point.

Anyhow here is my test scene (I'm doing a neon sign for Monday and this is an indigo test).

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Ok so far but when I turn one of the objects to an emitter this...

Image

I just need the emitter to work in the light of the first pic. Can someone prod me in the right direction? Also I assume that Indigo doesn't like 1 sided (shell) objects as the inside of one of those Z's which is left open is black inside. Any neon help would be nice as a bonus.


Many Thanks Russell[/list]

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Russdigo
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Post by Russdigo » Sat Apr 05, 2008 3:04 am

Image
Settings with the emitter

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Russdigo
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Post by Russdigo » Sat Apr 05, 2008 3:24 am

Image

Also emitter is black when poking out of the glass? The deep black is not shadow but part of the flat (with thickness) emitter.

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5OnIt
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Post by 5OnIt » Sat Apr 05, 2008 3:29 am

My guess is that you're going to have to use either Camera or Linear Tone mapping, not Reinhard.

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dougal2
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Post by dougal2 » Sat Apr 05, 2008 3:34 am

I think what is happening is that your "neon" emitter is much much brighter than your background illumination.

What are you using for the environment? background color? large mesh emitters? sun+sky?

I think that if you do a test with a physical sky without touching your "neon", you'll end up with an image similar to your first one.

It's a case of balancing the emitter powers against each other - which in indigo is not _quite_ the same as light powers in real life, despite Indigo's "realism" in most situations.

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dougal2
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Post by dougal2 » Sat Apr 05, 2008 3:42 am

BTW, I modelled this:
http://www.indigorenderer.com/joomla/co ... a=neon.jpg

by:
1. first making the glass tubes
2. dupplicate the tubes, and ALT-S (in edit mode) to "shrink" the copy inside itself
3. make the "inner" an emitter
4. make the outer a coloured glass (I also used some SSS to soften the colour a bit)
5. duplicated the parts of the tube that I wanted black, and ALT-S "fattened" them over the original, and coloured then solid black.

I didn't use any environment lighting at all in this scene.

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Kram1032
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Post by Kram1032 » Sat Apr 05, 2008 10:19 am

Just besides all the help on the main problem: Don't forget to add an edge-split modifier on the tubes, to get rid of the blacked out tris (normalsmoothing errors ;) )

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Russdigo
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Post by Russdigo » Sat Apr 05, 2008 9:06 pm

What are you using for the environment? background color? large mesh emitters? sun+sky?
Its a background colour, maybe I should use all emitters with emitter planes above the scene.

Thanks for all the replies I will get back monday/tuesday with the result.
edge-split modifier on the tubes, to get rid of the blacked out tris (normalsmoothing errors
Is this a Blender function?


Cheers Russell

Vanessa07
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Post by Vanessa07 » Sat Apr 05, 2008 9:42 pm

Russdigo

Is this a Blender function?
Yes, you can find it in the modifier, it's realy usefull in blender; have a look to them :)

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delic
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Post by delic » Sat Apr 05, 2008 11:20 pm

When adding edge split to a mesh, it doesn't create the smoothing pb(black borders on smooth objets) ?

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Post by Vanessa07 » Sun Apr 06, 2008 4:27 am

delic

It resolves many smoothing problem :)

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alexmeyer
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Post by alexmeyer » Sun Apr 06, 2008 7:10 am

On the same note as dougal, about the emitter power vs the rest of the lighting, scale also plays a role in the power settings for emitters. Wattage gets spread across the size of the object. Two objects that have the same power settings (eg. 100W, 17.5 lm/W), but are different sizes (say, 1m^2 and 50m^2) will have very different brightness levels.

Another example... I just got done doing a scene in which I had huge meshlights (6x18 meters), and they're set to about 15,000W 1,000lm/W.
(They do also have to compete with the sun, which is another fun thing to deal with, so that also bumps it up. But you get my point)

One Blender unit = 1 meter in Indigo. Check to see how big you're modeling everything, and if you need to tweak the scene scale afterwards, just go to Environment>Worldscale in Blendigo and mess with the multiplier there.

Hope that helped... :P
From uncyclopedia.org, on "Elephant's Dream":

"The choice of the title is highly significant, because while the movie does not feature any elephants nor dreams, no one understands what happens anyway."

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Russdigo
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Post by Russdigo » Sun Apr 06, 2008 8:06 pm

alexmeyer wrote:Two objects that have the same power settings (eg. 100W, 17.5 lm/W), but are different sizes (say, 1m^2 and 50m^2) will have very different brightness levels.

Hope that helped... :P
That would have really helped 11hrs ago when I set off the render before going to the pub. 8) Actually I don't think I would have quite understood it without seeing the results this morning. I'm not going to post it here at the moment as its on my other computer which is fully committed and needs to keep going till Monday. You are very right though, I've written "Zero Tolerance" in neon (magazine cover) and the short bars of the A and R leg which are separate are glowing to over exposure... Luckily though the sign is suppose to be on the fritz.

Heavy photoshopping I think. Anyhow despite my errors its good to do a real world test of Indigo.

BTW After 7hrs my Pentium D (the oldest dual core) 3GB with 3 threads on a 2000 x 1275 image is at - 717190000 samples (286.876 samples per pixel) 25170.02360 samples per second, Image has noise but its clearing.

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Russdigo
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Post by Russdigo » Tue Apr 08, 2008 7:49 am

Ok my mag center spread is finished, it was a compromise due to time and learning Indigo and Blender but an interesting real world test.

The hard part was that I had to have the neon against white, as it with text. I ran out of time to play around with Indigo and decided to do two renders on two different machines and use my Pshop skills if it all went pear shaped.

Image
Image
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Russdigo
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Post by Russdigo » Tue Apr 08, 2008 7:51 am

And the final shopped version.

Image

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Last edited by Russdigo on Tue Apr 08, 2008 11:55 pm, edited 4 times in total.

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