VRay 3Ds Max Understanding HDRI and Environment Lights

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  1 Week Ago
VRay 3Ds Max Understanding HDRI and Environment Lights

ver 3Ds Max 2014 and VRay 3.20.02

I'm trying to get a handle on VRay for 3Ds Max, specifically in understanding how HDRI, the environment settings, GI, and VRay Dome light all work with one another. I've watched a few tutorials online but they never really go into specifics. At most they say "create dome light, add HDRI image, check GI, render, done" and what they get looks good. Cant say i'm getting the same results though.

If possible can someone clear things up for me.

This is a render of the teapot in a blank scene with an HDRI image mapped to the texture section of the dome light. GI is activated and there are no other lights in the scene. In the material editor for the HDRI image I have to crank its render multiplier to 70 otherwise the image will render near black. (it is the opposite in some tutorials i've seen where the multiplier is left at 1 but they still get good results). Even at 70 this image looks dark to me. Maybe 70 is an average number but every tutorial i've seen leaves the multiplier at 1. GI light is active set to Irradiance map and Light Cache.



One part I get confused on is the relationship and difference between the environment map in the "Environment and Effects" window and the GI environment in the render settings rollout under the VRay tab. It seems whether theyre on or not makes no difference in the rendered image, and thats both with and without the same HDRI mat loaded. So what are they used for if they dont do anything?





So whats the difference between these two or are they the same thing? The only thing i've noticed is that the Environment and Effects map allows the image to be viewable in the viewport background. The other one does not.

this is the HDRI image i've been using.

 
  1 Week Ago
Originally Posted by Killer_Lettuce: This is a render of the teapot in a blank scene with an HDRI image mapped to the texture section of the dome light. GI is activated and there are no other lights in the scene. In the material editor for the HDRI image I have to crank its render multiplier to 70 otherwise the image will render near black. (it is the opposite in some tutorials i've seen where the multiplier is left at 1 but they still get good results). Even at 70 this image looks dark to me. Maybe 70 is an average number but every tutorial i've seen leaves the multiplier at 1. GI light is active set to Irradiance map and Light Cache.


When you import a 32bit HDR/EXR they have exposure settings, if you have adjusted this then it will effect the exposure on import, thus you are then readjusting this in the material editor (import -70, adjust in material editor +70 etc). Lots of decent HDRIs are setup to come into 3dsmax as correct when left at default (Peter Guthrie, CGSource etc).

Originally Posted by Killer_Lettuce: One part I get confused on is the relationship and difference between the environment map in the "Environment and Effects" window and the GI environment in the render settings rollout under the VRay tab. It seems whether theyre on or not makes no difference in the rendered image, and thats both with and without the same HDRI mat loaded. So what are they used for if they dont do anything?


Essentially it makes no difference as to which you use, they can be used for different scenarios.

Environment & Effects - This will display as you have adjusted the exposure in the material editor, in your case +70. This also allows you to use the Environment tab in the Render settings as an override as to what you see instead of what is being used for the GI - lots of cases people decide they want to use a Black override as this makes using your alpha much easier when it comes to 'fringing'

Environment in Render tab - You can use this purely instead of using a HDRI Dome or Environment & Effects, however you cannot over ride the background image this way. You have a separate multiplier here if you want to crack it up/down a few notches.

HDRI Dome Light - Another way of doing the same thing - it used to have slightly more noise as you were relying on the light subdivs of a light instead of a map, however not sure these days (I dont really use this method anymore). Either way, it should give you the same result, it has its own multiplier you can adjust as the light intensity.
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  1 Week Ago
Originally Posted by NorthernDoubt: When you import a 32bit HDR/EXR they have exposure settings, if you have adjusted this then it will effect the exposure on import, thus you are then readjusting this in the material editor (import -70, adjust in material editor +70 etc). Lots of decent HDRIs are setup to come into 3dsmax as correct when left at default (Peter Guthrie, CGSource etc
I've been getting HDRI's from here https://hdrihaven.com/ and when I import to Max the dialog looks like this


Compared to the preview jpg they provide (the image in my first post) the HDRI here is much darker and has greater contrast. Is there a reason for this or is it done with the expectation I'll be adjusting the multiplier? They are from a free site so maybe that has something to do with quality or their default settings? The website claims the images are unclipped and that they should be accurate by default.

I've also noticed the exposure settings are limited in the import window. If I bump the exposure up even the slightest bit the image appears blown out.

Quote: Environment & Effects - lots of cases people decide they want to use a Black override as this makes using your
alpha much easier when it comes to 'fringing'
What do you mean by fringing?

Quote: HDRI Dome Light - Another way of doing the same thing - it used to have slightly more noise as you were relying on the light subdivs of a light
instead of a map, however not sure these days (I dont really use this
method anymore). Either way, it should give you the same result, it has
its own multiplier you can adjust as the light intensity.
Is there a newer/better/different method used these days that I should be practicing? Everything I find looks almost too simple to be true. Its usually make dome light activate GI and youre done. Or Make Sun...finished.

Last edited by Killer_Lettuce : 1 Week Ago at 02:44 PM.
 
  1 Week Ago
That's a gamma issue. Is your scene and 3ds max set up with correct gamma 2.2 workflow?
 
  1 Week Ago
Originally Posted by Killer_Lettuce: I've also noticed the exposure settings are limited in the import window. If I bump the exposure up even the slightest bit the image appears blown out.


as catche mention, you gamma looks incorrect to me. Set it to 2.2

Originally Posted by Killer_Lettuce: What do you mean by fringing?

Fringing is when you render an image and you try to replace the background with something else, lets keep it simple for simple sake: You have a blue sky in your render, in post you replace it with a red sky, around objects such as tree leaves you will see blue pixels - this is fringing. You will know when you see it

Originally Posted by Killer_Lettuce: Is there a newer/better/different method used these days that I should be practicing? Everything I find looks almost too simple to be true. Its usually make dome light activate GI and youre done. Or Make Sun...finished.

Simple is often better, go with what makes your life better as long as it doesn't make other parts of your life worse. Everyone uses different workflows for different reasons, you will find you will change your workflow when you face other technical challenges.
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  1 Week Ago
Originally Posted by catche: That's a gamma issue. Is your scene and 3ds max set up with correct gamma 2.2 workflow?
Gamma is at 2.2. under the Color Mapping rollout. Type Reinhard, multiplier and burn value are also 1. Affect background box is checked. Basically I've left everything at default except for the Irradiance Map being set to the Low preset.

If you mean the Gamma/LUT tab in the preferences that was not active. As far as my job goes we leave it off as it causes strange behavior with some renders where after a frame is finished it greatly changes the saturation of the image. But I went ahead and activated it leaving it at 2.2. The HDRI map for the material did change to have accurate colors like those of the preview jpg they provide. However it doesn't seem to have changed the results of the render.

Again I can bump up the processing multipliers for the material but it seems like you're not exactly supposed to have to bump them up as much as i'm having to.

Originally Posted by NorthernDoubt: Fringing is when you render an image and you try to replace the background with something else, lets keep it simple for simple sake: You
have a blue sky in your render, in post you replace it with a red sky,
around objects such as tree leaves you will see blue pixels - this is
fringing. You will know when you see it
Oh yeah I know what you're talking about. Ive never really given it a name but I always premultiply images in AE or defringe in PS to get rid of it.
 
  1 Week Ago
in the vray vfb, you also have to check the srgb curve

look here

You don't have to manually choose 2.2 gamma when saving images or loading textures, though. Not unless it's been changed away from the defaults of 3ds max. You can check this by typing fileoutgamma and fileingamma down-left in the pink area. If it prints 2.2 in the below area, then you're all good.

Last edited by catche : 1 Week Ago at 11:09 PM.
 
  5 Days Ago
Originally Posted by catche: in the vray vfb, you also have to check the srgb curve

look here

You don't have to manually choose 2.2 gamma when saving images or loading textures, though. Not unless it's been changed away from the defaults of 3ds max. You can check this by typing fileoutgamma and fileingamma down-left in the pink area. If it prints 2.2 in the below area, then you're all good.
So I went through and copied whats in that link and the image renders very dark. It would be correct if it were a night time image but the HDRI i'm using is in broad daylight. This is what my render looks like matching the settings in that link


This is one of the video's I was referencing when starting this. He says he's left just about everything at default but the render he gets matches the lighting of the HDRI he's using. There were several others I watched and they had near default settings as well and were getting similar results. I'm having to crank numbers way up to get close to that so it leads me to believe i'm missing something here.

 
  5 Days Ago
Hmm yes, something must be wrong. Are you able to save the file somewhere for me to download and investigate? Doesn't need to include much at all.

Another thing you could try, is to make a sphere (1m diameter let's say) on a plane, add vray sun+sky, set its intensity to 0.03, and render. This should look like a pretty normal day. With GI on and the light at a ~45 degree angle, also.
 
  4 Days Ago
I PMd you a link to the download.

I did try the sun thing you mentioned and the render appears dark if I have the Gamma/LUT box unchecked in preferences. It ONLY appears accurate with the gamma/LUT box checked. Is this a normal process for VRay, to always have that checked? For reasons i'm not entirely sure of the Gamma/LUT is always left off for any scene I get through work but things still render fine, but we also dont use HDRI maps very often and only really in specific circumstances. If you use an HDRI does that mean the Gamma/LUT should always be turned on as well?
 
  4 Days Ago
If you want to keep the Gamma LUT turned off you can follow a tutorial I made on setting up Vray renderings using this method below:

http://jamesvella.blogspot.com/p/tutorial.html

It should get you off to the right start, setup the lighting and balance the image to show correct dulux colours and camera settings. Let me know if you get stuck
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