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Luxus discussion II
Posted: 23 August 2013 09:46 AM   [ Ignore ]   [ # 316 ]
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Do you have an example of how/when this would be used?

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Posted: 23 August 2013 09:53 AM   [ Ignore ]   [ # 317 ]
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SphericLabs,

Do you have any idea why Luxus would generate a truncated lxs file?  I can’t attach the file here because it’s too big even compressed.  I can’t even post the last line as code because it is too long.  The last section is “shape mesh” and it gets truncated in the “float uv” line after ~99565 characters.  The end of the line looks like this:

0.8933445 0.4742435 0.9012145 0.471962 0.90 

So you can see that it just stops abruptly in the middle of the line.  When this lxs is read into LuxRender, it causes a syntax error on this line.  I get this with almost every but the most simplest of scenes when using Luxus as the exporter.  The same scenes work perfectly with Reality.

After a bit of troubleshooting, I noticed the lxs file for this scene is always getting truncated at 90,908 KB.  If I hide some of the objects so it falls below that number, then it works - regardless of which objects I hide.  This is how I know that it’s not related to any particular object in the scene.  I opened another scene and Luxus truncated the lxs file when it went above 60,607 KB.  So the threshold is not always the same.

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dpm316

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Posted: 23 August 2013 01:57 PM   [ Ignore ]   [ # 318 ]
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Repeat posting, no-one’s answered this yet:

SphericLabs - 20 August 2013 10:26 AM

LuxRender documentation is found on luxrender.net
-> http://www.luxrender.net/wiki/Main_Page

I know about the LuxRender wiki, I have it bookmarked and I’m constantly browsing through it. If it mentions the LuxRender GUI, that bit’s hiding.

Another couple of questions:

Lights. I’m having mostly very good results applying light materials to lightbulbs in a room, but when I try illuminating e.g. windows in a spaceship model, it’s as if each tiny little light has a WW2 searchlight behind it. And I can’t turn them down easily — turning colour RGB values towards 1,1,1 and power down to 1W or less, it’s either still glaring bright or much too dim. Sometimes two bits of mesh with the same surface can be both at once. This one’s downright weird.

Also, is there any way to get a sky light to shine through a skydome/skybox, or should I try an HDRI map on the light?

Luxus materials: are there any links to collections? I’m discovering Poser materials are more often than not better than D|S settings, but some things e.g. water I think I need a bit more help with.

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Posted: 23 August 2013 04:29 PM   [ Ignore ]   [ # 319 ]
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SpottedKitty - 23 August 2013 01:57 PM

Lights. I’m having mostly very good results applying light materials to lightbulbs in a room, but when I try illuminating e.g. windows in a spaceship model, it’s as if each tiny little light has a WW2 searchlight behind it. And I can’t turn them down easily — turning colour RGB values towards 1,1,1 and power down to 1W or less, it’s either still glaring bright or much too dim. Sometimes two bits of mesh with the same surface can be both at once. This one’s downright weird.

I can try to help you with this one. Setting intesity on Mesh lights seems to do little. I use the color to adjust them. In the LuxRender GUI you can select the color of lights. If you want white light use the grey scale to bring it down.

Also, you can set light intensity in the Lux Gui if you have more than one light source. If you only have one it does now good.

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Posted: 23 August 2013 05:13 PM   [ Ignore ]   [ # 320 ]
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Vanguard - 23 August 2013 04:29 PM

Setting intesity on Mesh lights seems to do little. I use the color to adjust them.

Intensity, is that the same as “LuxRender Light - Power (Watts)” in a Luxus surfaces parameter list? The parameter names are so confusing and unexplained I think we’d better be precise with this. And I have tried tweaking the colour — lighting small mesh lights on a spaceship model, I started with default settings, colour full white (255,255,255) and power 100W. Glaringly bright, so I turned the power down in stages until it was set at just 1. Not glaring any more, but still way too bright. Then I started bringing the colour values down. I ended up with RGB values of 1,1,1 and many of the lights were still too bright. That’s what I can’t understand, it just isn’t easy to control these lights.

Colour is a bit of a head-scratcher as well. Many of the lights I add a map to just wash out to a single colour, frequently white whatever colour the light’s supposed to emit. And I can’t get red lights to look red, they all come out a bilious magenta-ish shade. And I don’t know what any of the other parameters do (the LuxRender wilki is usually no help here).

question

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Posted: 23 August 2013 06:00 PM   [ Ignore ]   [ # 321 ]
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SpottedKitty - 23 August 2013 05:13 PM
Vanguard - 23 August 2013 04:29 PM

Setting intesity on Mesh lights seems to do little. I use the color to adjust them.

Intensity, is that the same as “LuxRender Light - Power (Watts)” in a Luxus surfaces parameter list? The parameter names are so confusing and unexplained I think we’d better be precise with this. And I have tried tweaking the colour — lighting small mesh lights on a spaceship model, I started with default settings, colour full white (255,255,255) and power 100W. Glaringly bright, so I turned the power down in stages until it was set at just 1. Not glaring any more, but still way too bright. Then I started bringing the colour values down. I ended up with RGB values of 1,1,1 and many of the lights were still too bright. That’s what I can’t understand, it just isn’t easy to control these lights.

Colour is a bit of a head-scratcher as well. Many of the lights I add a map to just wash out to a single colour, frequently white whatever colour the light’s supposed to emit. And I can’t get red lights to look red, they all come out a bilious magenta-ish shade. And I don’t know what any of the other parameters do (the LuxRender wilki is usually no help here).

question

Yes, I was referring to “LuxRender Light - Power (Watts)” before. I never use that setting, it never seemed to make a difference.

Here is a set of pics depicting 4 mesh lights, simple planes with the LuxRender light material added to them and simply enabled, no other setting change on the materials.

After letting the render run for a minute or so I paused it to play with the light settings in the lux gui.

Pic 1 shows how changing the “Gain” in the lights changes their illumination / intensity.

Pic 2 shows similar but differing effect, this time all lights have gain set to 1 but use color to change intensity

Pic 3 shows that if only one light is enabled then changing the values has little effect, The panel that was darkest in the previous pictures is now the only light and is therefore bright.

My suggestion is to create simple scenes with lights and experiment on how they work. The LuxRender wiki stuff is highly technical and hasn’t helped me much.

The nice thing is you can play in realtime with the lights in the Lux GUi, all day long sometimes :p

Hope that helps

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lux1e.JPGlux1f.JPGlux1g.JPG
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Posted: 23 August 2013 06:19 PM   [ Ignore ]   [ # 322 ]
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Vanguard - 23 August 2013 06:00 PM

After letting the render run for a minute or so I paused it to play with the light settings in the lux gui.

I can do that? I thought once I’d started a render running I couldn’t twiddle the settings.

Edit: aaaand it seems to be making no difference. I caught the pause right after the first render pass, turned all the lights down to a gain of 0.01 then restarted, and everything’s glaring bright again after letting it run for 20 minutes.

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Posted: 23 August 2013 07:23 PM   [ Ignore ]   [ # 323 ]
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SpottedKitty - 23 August 2013 06:19 PM
Vanguard - 23 August 2013 06:00 PM

After letting the render run for a minute or so I paused it to play with the light settings in the lux gui.

I can do that? I thought once I’d started a render running I couldn’t twiddle the settings.

Edit: aaaand it seems to be making no difference. I caught the pause right after the first render pass, turned all the lights down to a gain of 0.01 then restarted, and everything’s glaring bright again after letting it run for 20 minutes.

Is your tonemapper(in the LuxRender GUI) autolinear?  If it is its adjusting the gain back.  Change it to linear for better control.

 

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Posted: 23 August 2013 07:53 PM   [ Ignore ]   [ # 324 ]
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It works, thanks!  cheese

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Posted: 23 August 2013 08:02 PM   [ Ignore ]   [ # 325 ]
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You shouldn’t have to pause it either.

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Posted: 23 August 2013 08:46 PM   [ Ignore ]   [ # 326 ]
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Is there a place to submit a bug report?

Thanks,
dpm316

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Posted: 23 August 2013 08:51 PM   [ Ignore ]   [ # 327 ]
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Gedd - 23 August 2013 08:02 PM

You shouldn’t have to pause it either.

True. I just paused it to keep the render from altering the look f the different shots I was trying to illustrate.

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Posted: 24 August 2013 01:36 AM   [ Ignore ]   [ # 328 ]
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What gets me even with Linear if we set a light mesh to say 5 watts in my mind the light should behave as 5 watts no matter if the light has a IES settings. For a realistic render engine I find this to be a tad annoying.

But I suppose I expect too much out of a Open Source project like Luxrender.

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Posted: 24 August 2013 05:20 AM   [ Ignore ]   [ # 329 ]
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Actually, that IS behaving like the real world.  An IES profile is applying a light spread profile to a light.  This mimics the reflector that a light in the real world would have to shape the light into that profile.  If a reflector concentrates the light, the visible effect is that the light seems brighter in the smaller area that it covers than it would if it had no reflector.  This is a basic principal in using studio strobes in photography, for example.

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Posted: 24 August 2013 06:37 AM   [ Ignore ]   [ # 330 ]
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Yeah which I am getting and I do understand what IES’s are and I am using them in a render now. Been going for 62 hours at 1.8 KS/p yes slow machine and that is in hybrid mode using one HDRI and two mesh light planes with IES profiles loaded and working as far as I can tell. Well there is a noticable difference with and without. But thank you cwichura for confirming I do understand this aspect.

What I have trouble with is why in Linear mode the Wattage adjustment seems to have no effect. Yes using Non Linear I see they work as expected with the right wattage for the right IES. BUT i want full control in Linear mode. Not Luxus’s fault granted.

Why? I find many HDRI’s hit and miss with how much light they should give out compared to how the HDRI looks when viewed in Photoshop. They seem to be a bright sunny day but when used as an HDRI they don’t seem to put out the same light as expected. Yes I have tried rotating the HDRI in DS. Probably poorly made HDRI’s granted and probably my fault for being cheap.

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