render and viewport show different results

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Dade
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Re: render and viewport show different results

Post by Dade » Tue Oct 23, 2018 6:51 pm

kintuX wrote:
Tue Oct 23, 2018 6:43 pm
Took a quick look and it seems either there's a bug(?) > Visible to Camera doesn't work!
I will check if this option has some specific issue with RT rendering modes.
kintuX wrote:
Tue Oct 23, 2018 6:43 pm
or, as it goes for many other unbiased & physically correct render engines: One cannot make emitter invisible & still cast light - it's either VISIBLE (& emitting light) or INVISIBLE (not emitting light).
For Lux, as the option says, it will make only the object invisible to the camera (i.e. first segment of the eye path); for anything else the object will be visible (i.e. mirrors, reflections, etc.). This solution doesn't cause any problem and it works in a similar way to arbitrary clipping plane (i.e. the clipped objects still exist and are visibile for everything but the camera).
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kintuX
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Re: render and viewport show different results

Post by kintuX » Tue Oct 23, 2018 7:07 pm

Dade wrote:
Tue Oct 23, 2018 6:51 pm
kintuX wrote:
Tue Oct 23, 2018 6:43 pm
Took a quick look and it seems either there's a bug(?) > Visible to Camera doesn't work!
I will check if this option has some specific issue with RT rendering modes.
kintuX wrote:
Tue Oct 23, 2018 6:43 pm
or, as it goes for many other unbiased & physically correct render engines: One cannot make emitter invisible & still cast light - it's either VISIBLE (& emitting light) or INVISIBLE (not emitting light).
For Lux, as the option says, it will make only the object invisible to the camera (i.e. first segment of the eye path); for anything else the object will be visible (i.e. mirrors, reflections, etc.). This solution doesn't cause any problem and it works in a similar way to arbitrary clipping plane (i.e. the clipped objects still exist and are visibile for everything but the camera).
Thanks, looks like i got much more to learn...
So I took another look.

The thing here is, that Area Lamp (object: Area.010) is always rendered as invisible to Camera (PT & BiDir) in case of reflections. Direct light with RT seems fine, but with PT & Bidir is pitch Black (invisibility works!).

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B.Y.O.B.
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Re: render and viewport show different results

Post by B.Y.O.B. » Tue Oct 23, 2018 7:28 pm

It seems the area lamp on the left is simply not emitting any light in final render, but works in viewport.
It could be a bug in the addon, I'll check.
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2018-10-23_21-27-04.png
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Re: render and viewport show different results

Post by B.Y.O.B. » Tue Oct 23, 2018 10:10 pm

I noticed that this area light has some uncommon scale values, e.g. -2.8 on the y axis.
Anyway, the problem is that apparently it is transformed in a wrong way in final render so that it emits light in the opposite direction.
In viewport render this does not happen. Viewport is different because everything is instanced (so that you can move objects around).

Here's the same light viewed from the other side:
Attachments
2018-10-24_00-07-44.png
2018-10-24_00-12-50.png
the problematic area light isolated. viewport left, final right.
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Dez!
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Re: render and viewport show different results

Post by Dez! » Thu Oct 25, 2018 4:32 am

This is great news!
I checked. Yes, a problem with a negative scale value at the light source. Hurried, and made such a mistake.
But!
As a result, we now know about this feature.
As a result, I now learned not only to put light sources to make a beautiful gloss. But also black planes. I did not think about it before.
As in the saying: "Live and learn"
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lacilaci
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Re: render and viewport show different results

Post by lacilaci » Thu Oct 25, 2018 6:00 am

Dez! wrote:
Thu Oct 25, 2018 4:32 am
This is great news!
I checked. Yes, a problem with a negative scale value at the light source. Hurried, and made such a mistake.
But!
As a result, we now know about this feature.
As a result, I now learned not only to put light sources to make a beautiful gloss. But also black planes. I did not think about it before.
As in the saying: "Live and learn"
If there is a ramp/gradient map in luxcore, you could also map black plane with gradient for opacity to get nice graduated reflection/lighting for your objects.

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Re: render and viewport show different results

Post by B.Y.O.B. » Thu Oct 25, 2018 8:41 am

lacilaci wrote:
Thu Oct 25, 2018 6:00 am
If there is a ramp/gradient map in luxcore
There is the "Blend" texture, in the "Textures (Blender)" section of the add node menu.
https://wiki.luxcorerender.org/LuxCoreR ... l_Textures
It can be configured to create a radial gradient.
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kintuX
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Re: render and viewport show different results

Post by kintuX » Sun Oct 28, 2018 2:09 pm

Another notice:
Emission material emits light only in one direction (normal, while backface is black) which makes it cumbersome when used on flat (non-solid) 'twisting' geometry. 'Solidify' fixes this, but with 'Rim' on, is more than doubling the number of lights.
eg
emitter_flatbad-solidgood.jpg
emitter_flatbad-solidgood.jpg (11.1 KiB) Viewed 123 times
Is double sided emitter supported in LuxCore? If so, how can it be enabled in the addon?
(I still don't understand how all this relations "Blender addon <=> LuxCore" works.
ie. i wanted to represent Linear Camera Scale value 10x the value of input and do the multiplication in the back but i got totally lost :? :roll: am starting to think coding is just not for me or it really takes long - same as whole life development :) )

PS
Also, while i'm at it, is the "RaySwitch" concept applicable to LuxCore?

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Dade
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Re: render and viewport show different results

Post by Dade » Sun Oct 28, 2018 2:36 pm

kintuX wrote:
Sun Oct 28, 2018 2:09 pm
Another notice:
Emission material emits light only in one direction (normal, while backface is black) which makes it cumbersome when used on flat (non-solid) 'twisting' geometry. 'Solidify' fixes this, but with 'Rim' on, is more than doubling the number of lights.
eg
emitter_flatbad-solidgood.jpg

Is double sided emitter supported in LuxCore? If so, how can it be enabled in the addon?
No but there is a trick to get double side lights: you can use an 1x1 image map of a white pixel as IES map to emit lights in all directions with constant values. Using something like a 512x512 image you can just "draw" how you want the light to be emitted (only in one hemisphere, with varying intensity, etc.).
kintuX wrote:
Sun Oct 28, 2018 2:09 pm
PS
Also, while i'm at it, is the "RaySwitch" concept applicable to LuxCore?
No and it is unlikely it will ever been supported (i.e. it is very not physically based).
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Sharlybg
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Re: render and viewport show different results

Post by Sharlybg » Sun Oct 28, 2018 3:12 pm

No and it is unlikely it will ever been supported (i.e. it is very not physically based).
I also really really don't like such heavy biased feature.
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