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bmargolas
09-22-2004, 11:38 AM
I have been rendering a scene and the final product has little white spots on it. It is strange b/c when I render with antialiasing off or on low it doesn't happen, but when its on high it does. Does anyone know why this is happening and how I can fix it?

mattclary
09-22-2004, 12:29 PM
A picture is worth a thousand words, show us what you mean.

bmargolas
09-22-2004, 12:48 PM
as you can see that there are tiny white specks randomly around in the picture as well as a large black error in the bottom left.

mattclary
09-22-2004, 01:43 PM
Interesting image.

The black mark is probably caused by bad geometry. Im Modeler, merge points, open poly stats, select all 2 point polys and delete them. Then select all non-planar polys and triple them. Retry the render, that should fix the black thing and it MIGHT fix the dots.

If the dots are still a problem, there are various settings that might be causing this. I think refraction levels might, ray recursion might affect it. Try adjusting shading noise reduction. I'm not as sure with these, but play with them a little and see if it makes a difference.

bmargolas
09-22-2004, 02:56 PM
maybe I should mention I'm working with a subpatch suface.

bmargolas
09-22-2004, 05:58 PM
I was using the BRDF shader and when I turn it off the problem goes away. The effect that this shader adds is what I am really enjoying, so anyone know how to still use it while solving these problems?

toby
09-22-2004, 09:02 PM
That is a bug with Raytraced reflections when used with BRDF. Try switching to a reflection map, or render the reflections separately

bmargolas
09-22-2004, 10:48 PM
how do I go about rendering reflections seperatly?

mattclary
09-23-2004, 05:10 AM
Does the black mark go away when you stop using BRDF?

toby
09-23-2004, 12:27 PM
Go to the 'Effects/Processing' tab, under 'Add Image Filter' add 'Render Buffer Export', set it to 'Reflection' and set the output path. In Photoshop or After Effects layer this image on top and set the blend mode to 'screen'.

bmargolas
09-23-2004, 02:16 PM
the black spot did go away when i took the filter off.

bmargolas
09-23-2004, 04:10 PM
so, that it? I don't need to take the reflections off the original image? Just add that to the image filters and render, or is there something else involved?

toby
09-23-2004, 09:17 PM
Render 1 image without raytrace reflection with the BRDF, then render an image with raytrace reflections and without the BRDF, but only use the buffer image. Your reflections will not have the BRDF reflected in them but you might not be able to tell. Anyway, until they fix the bug it's the only practical solution ~

dyls_E
01-25-2018, 12:39 AM
at first i liked a couple of white dots, thinking it looked like imperfections in film, but now they are just annoying the hell out of me haha. i work at a place that mostly does renders of cars, and the car paint material does it now grrr

UnCommonGrafx
01-25-2018, 03:34 AM
Your lights are too close when you start getting fireflies.

jwiede
01-28-2018, 07:41 PM
That is a bug with Raytraced reflections when used with BRDF. Try switching to a reflection map, or render the reflections separately

Is there a thread about this bug (describes in more detail) somewhere?

dyls_E
01-28-2018, 08:50 PM
Your lights are too close when you start getting fireflies.

yeh i know what you are talking about, little hot spots, this is something different. here is one using only a distant light. there is something going on with the reflections. Driving me nuts. turn up all the settings and nothing seems to help. here is a quick render to just show what is happening. 1 distant light 139819

UnCommonGrafx
01-29-2018, 03:22 AM
What's the light sample? Is it past 64?

adk
01-29-2018, 03:59 AM
I get these as well, on a pretty simple product render test ( a copy of a c4d scene I saw on y.tube)
Lit with a HDRI (no lights at all) so it's pretty easy to see via the buffers which samples clean what.
Apart from camera AA there's only really three places where you can throw samples at this.

Environment Light - Samples / MIS Samples (limited extent)
Reflection Samples
Refraction Samples

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As much as I like the new render engine and workflow for optimising renders it seems like I'm missing something vital to make the BSDF option workable for animation ?
Some guidance from NT as to how best that's achieved isn't too much to ask for I reckon.

3 minutes for a 640x640 px render (with marauding hot pixels) is not gonna set any records that's for sure.



Your lights are too close when you start getting fireflies.


... here is one using only a distant light. there is something going on with the reflections. Driving me nuts. turn up all the settings and nothing seems to help. here is a quick render to just show what is happening. 1 distant light

By definition a "distant light" should never be too close to anything :D

UnCommonGrafx
01-29-2018, 04:26 AM
Ha, couldn't argue that.
Fortunately, we are talking about a realm where the physically impossible is, actually.

What are your light samples? 3 minutes for the cans?
Ha, I'm betting it's the floor that's adding a lot to your time.


NewTek has offered tips about this, it's in the docs. I'm sure if you give it a read you'll be able to clean that up quickly.

Light samples, reflection samples, no need for gi... It's a tweak happy renderer.
Robert

MichaelT
01-29-2018, 06:56 AM
Render 1 image without raytrace reflection with the BRDF, then render an image with raytrace reflections and without the BRDF, but only use the buffer image. Your reflections will not have the BRDF reflected in them but you might not be able to tell. Anyway, until they fix the bug it's the only practical solution ~

As I understand it.. BRDF isn't using the reflective channel. You'll will find those under Specular_Indirect however.

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ActionBob
01-29-2018, 07:47 AM
I find that with this type of renderer, using two versions of an environment map will help out with hot spots. I might be off, but I seem to recall that you use the high res map as your environment / reflections and a lower res / blurred version for the lighting. At least I seem to recall this helping in Octane. But I haven't touched any 3D stuff in a while.

Probably way off as I haven't had my coffee yet...

-Adrian

jwiede
01-29-2018, 10:05 AM
I find that with this type of renderer, using two versions of an environment map will help out with hot spots.

These aren't typical "micro-hotspots", note where they're happening in the car image above. It does appear to be some kind of reflection-related bug.

gerry_g
01-29-2018, 01:41 PM
I think the values at those points are dynamically too out of range to be dealt with, think the photo real PBR side of thing sits uncomfortably with the old standard side of things, they need to be better reconciled. The other day I plugged a colour layer in and used it as an alpha gradient to affect a falloff transition between two surfaces on a material mixer node and got fireflies everywhere, when I switched the gradient to a scaler layer every thing was fine, I suspect the colour layer had too great a dynamic range. Long and short is although theoretically you can mix and mach and do what you like, in reality you do so at your peril.

MarcusM
01-30-2018, 01:12 PM
Hot pixels are visible in LW documentation describing BSDF (LW logo):
https://docs.lightwave3d.com/display/LW2018/Principled+BSDF

Roughness spheres looks terrible:
https://docs.lightwave3d.com/display/LW2018/Principled+BSDF?preview=/1857328/1857330/Principled_Spheres_Layout.png

Principled parameters in Blender to compare:
https://docs.blender.org/manual/en/dev/render/cycles/nodes/types/shaders/principled.html?highlight=bsdf

jwiede
01-30-2018, 10:56 PM
Roughness spheres looks terrible:
https://docs.lightwave3d.com/display/LW2018/Principled+BSDF?preview=/1857328/1857330/Principled_Spheres_Layout.png

Yeah, at quite high roughness values pBSDF just looks "off", the expected "retroreflective" rim response isn't present, etc. Seems like might be a bug or tuning issue?

dyls_E
08-20-2018, 07:52 PM
i think it might have been distant light causing my issues... i thought that would be the safest light to stop noise or spots, but i'm not getting any spots when i remove the distant light

Tobian
08-21-2018, 03:06 AM
Wow amazing someone was using LW 2018 in 2004... I think this thread has been somewhat hijacked... :)

The thing about distant lights is they are insanely bright, from a noise perspective, you should do this as an experiment, increase the angle, so it is multisampling and slightly soft (aka a sun), and untick normalise. now increase the intensity so it matches what it did before. it's a huge number, around 10k LUX depending on your light, which is why you can often get silly fireflies from them. the other major source of noise is from the environment, because of the way the engine is built either use the environment light properly, or stop complaining, my tutorial is even in the manual...

jwiede
08-21-2018, 07:58 PM
Wow amazing someone was using LW 2018 in 2004... I think this thread has been somewhat hijacked... :)

The thing about distant lights is they are insanely bright, from a noise perspective, you should do this as an experiment, increase the angle, so it is multisampling and slightly soft (aka a sun), and untick normalise. now increase the intensity so it matches what it did before. it's a huge number, around 10k LUX depending on your light, which is why you can often get silly fireflies from them. the other major source of noise is from the environment, because of the way the engine is built either use the environment light properly, or stop complaining, my tutorial is even in the manual...

Which still doesn't explain fireflies in cases like gerry_g's post above, or the anti-aliasing case described by the OP.

Artpix
02-12-2019, 12:33 AM
You probably already solved this? I noticed how to work with me right. Reflection samples 2 and Minimun samples 2 then pure rendering. If Reflection samples is 1 and minimum 1 then white spots appear. I believe that the key to success is in these sampl matters.

gerry_g
02-12-2019, 03:43 AM
move to LW2019 and check 'despike' in render properties, works like magic, yes samples are still very applicable but with glossy reflections on some things just won't budge at some level, renderer is way better too, better calibrated to low light and interior shots