Has anybody ever accomplished a GI-type render like this in 3ds Max?

ozzman1997

I've been trying...and trying...and trying to get a shading effect like this, but am getting nowhere. MR with skylight + portals, brute-force Final Gather calculations (interpolation set to zero, and takes several hours to finish) Scanline with Light Tracer, even GI from the V-Ray demo and nothing comes close. I need this kind of shading baked into my textures because the game engine that it's going into doesn't use PBR or any other rendering techniques for areas that are not illuminated with diffuse sunlight, so ambient occlusion still looks a bit odd by itself. 

To me, there seems to be some kind of direct lighting going on here. Look how the rudder pedals cast shadows down onto the floor in the first pic...I've never seen a skylight cast shadows like that unless there are no light bounces, which would make the cabin lighting much, much darker than it is here. I honestly don't know what else to try that won't take several days to render.  

Any suggestions would be appreciated. 

Axi5

Given the reflections, this looks a lot like a specular AOV

ozzman1997

Axi5 said:

Given the reflections, this looks a lot like a specular AOV

What exactly does that mean? The only things I'm seeing online pertaining to those keywords involve the new Arnold renderer for Max 17...But it didn't exist in 2013 when these images were created. 

musashidan

It means it's a diffuse(for example mid-grey)render pass, an AO render pass and a reflection render pass composited together. It's what's commonly called a 'Clay Render', which in this case also has reflections.

The shader could also be created directly and output as a single beauty render pass - which negates the need to comp the passes in post.

In Vray, for example, it would just be a vray material with a vray dirt map in the diffuse slot and high glossy reflection settings.

Here's an example of my own work rendered this way in Vray:

ozzman1997

musashidan said:

It means it's a diffuse(for example mid-grey)render pass, an AO render pass and a reflection render pass composited together. It's what's commonly called a 'Clay Render', which in this case also has reflections.

The shader could also be created directly and output as a single beauty render pass - which negates the need to comp the passes in post.

In Vray, for example, it would just be a vray material with a vray dirt map in the diffuse slot and high glossy reflection settings.

Here's an example of my own work rendered this way in Vray:

Hmm. Maybe that's just what VRay's ambient occlusion looks like then. I do remember hearing somewhere that the original work actually was done in VRay, but I thought that MR should be able to replicate it since the concept of AO is pretty similar regardless of what engine is used to produce it. I've spent the last couple of hours playing with the settings in MR's ambient occlusion material and got some semi-satisfactory results, but only because I cranked up the maximum radius to about twice the size of my entire scene, and maxed the spread out to 1.0 in order to somewhat mimic the effect of a skylight with Light Tracer, but with less grain and faster render times at the expense of less contrast (although I can mostly make up for that using exposure control.) 

Now, when you say a "diffuse pass", are you talking about another lighting setup altogether, or are you just referring to the base material color? 

throttlekitty

Just to correct you @musashidan, AOV is Arbitrary Output Variable, it's the "next gen" of render passes. But instead of re-rendering each pass from scratch, you get the desired info for free, split off from the main render. And those images look nothing like a specular AOV. Anyway.

@ozzman1997  This looks like a GI render to me. There's a bunch of tuts out there for rendering interiors with GI. Really all you need for basics is a dome or sun light and some light portals - This is where that interior direct and bounce light is happening. They act like attractors for the lights that they are attached to, effectively focusing the rays to go through the windows. The plane's cabin is convenient for lighting, what with all the windows, some long portals along either side, and a few for the front windows should do.

Additionally, the portals don't *need* to be outside or even around a window. You could throw additional ones inside as sphere or cylinder shapes for an extra boost if you need it. (or just boost with regular lights on the inside, i guess that might be smarter)

Here's a quickie since I've been meaning to play with this too. This box has some holes punched out and a portal light on all four sides. Needs work obviously.

musashidan

What version of Max are you using? What renderers do you have access to? Is your scene in real-world scale? From my memory of using MR years back it has a decent AO output. Yes, a diffuse pass is just a 100% diffuse shader.

Multiplying the AO in post as a layer will give you more control. With Vray dirt map you can nest additional maps to ramp up the effect without cranking the settings too high.

Here's an old clay render of mine using MR AO:

musashidan

throttlekitty said:

Just to correct you @musashidan, AOV is Arbitrary Output Variable, it's the "next gen" of render passes. But instead of re-rendering each pass from scratch, you get the desired info for free, split off from the main render. And those images look nothing like a specular AOV. Anyway.

@throttlekitty yes, I haven't messed with AOVs yet as it's been a while since I've done any illustration(comping/paintover) work. This isn't necessarily 'next-gen' though. This has been possible for years using .exr

Edit: OP - thinking about it now I remember there was a setting in MR to boost global GI AO. Maybe that's been modernised since then, though.

With renderers pushing more towards brute force pathtracing, a lot of these 'tricks/hacks' like irradience maps and light cache are gradually starting to phase out. Interiors have always been the weakness of pathtracing though, and forced bounce lighting and light portals(as throttlekitty mentioned) are often used to 'push' more lighting into the scene and clean up the noise.

throttlekitty

nooo everything is next gen, forever! (it's a new thing to me, i've been on the 'old' mental ray in maya for years and i'm in love with this new stuff)

Another point about AO vs GI is in the smaller details, the cockpit panel in particular doesn't have that classic "look" from AO being too strong in the small areas.

ozzman1997

throttlekitty said:

nooo everything is next gen, forever! (it's a new thing to me, i've been on the 'old' mental ray in maya for years and i'm in love with this new stuff)

Another point about AO vs GI is in the smaller details, the cockpit panel in particular doesn't have that classic "look" from AO being too strong in the small areas.

I noticed that too, compared to my attempts it doesn't have that "dirty" shading around switches and knobs, just more of a soft directional light. I was really surprised that AO could *almost* pull off directional shadows, but it's not quite the same. The more I increase the max distance for AO, the more it resembles a skylight, but render times start to go through the roof...to the point where I might as well just be using Light Tracer. 

musashidan said:

What version of Max are you using? What renderers do you have access to? Is your scene in real-world scale? From my memory of using MR years back it has a decent AO output. Yes, a diffuse pass is just a 100% diffuse shader.

Multiplying the AO in post as a layer will give you more control. With Vray dirt map you can nest additional maps to ramp up the effect without cranking the settings too high.

Here's an old clay render of mine using MR AO:

I run Max 2015 with the standard Max renderers (MR, Scanline, iRay) and yes, my scene is real-world scale. 

Except for the sunlight coming through the window, the image above is relatively close to what I've been getting with pure AO. My only gripe with using AO in this way is that no matter what exposure settings I use (or what post production is done in Photoshop) the image lacks any kind of dynamics in the upper and lower ranges, if that makes any sense. For example the shadows seem a bit washed out until a certain point where they drop off to pure black, and there seems to be the same kind of threshold on highlights as well. So trying to get decent contrast has been a nightmare. 

Also tried the portal lights again...with the same results as before. It seems like they aren't "punching" through the windows as they should, without having to crank up the multiplier to 20 or so...and even then, it becomes a dull, washed-out source of light. 

throttlekitty

With your portal light tests, what materials are you using, and where are your portal lights physically placed? You want some semi-brightly colored physical material to keep the light bounce going, but still balanced where your lights aren't blowing out.

edit: I guess material use depends on what your options for baking lights in max is.

ozzman1997

throttlekitty said:

With your portal light tests, what materials are you using, and where are your portal lights physically placed? You want some semi-brightly colored physical material to keep the light bounce going, but still balanced where your lights aren't blowing out.

edit: I guess material use depends on what your options for baking lights in max is.

My material is usually Arch & Design in the neutral grey that it is by default, but sometimes I choose white instead. It doesn't seem to make much of a difference apart from overall brightness which can be tamed using exposure control. And the portals are slightly larger than my windows, placed about 5-10cm from the opening. 

I tried putting a portal light in each cabin window, which during the FG calculations looked more like what I'm after, but upon the final interpolation it smudges all of my details out. Increasing the FG density and rays to combat this drastically increases render time, and the final result is still grainy for some reason. 

musashidan

Have you tried using Iray: Brute-force pathtracing as opposed to FG?

Saving your renders to 32bit .exr will give you a lot more range to work with when crushing whites/blacks in post. I still would always advise comping passes in post. It just simply gives much more flexibility and saves hours of render time(believe me, I've been there )

musashidan

throttlekitty said:

nooo everything is next gen, forever! (it's a new thing to me, i've been on the 'old' mental ray in maya for years and i'm in love with this new stuff)

Question? Why not Arnold? Brute force Pathtracing is a lot more accurate than a 'hack' like FG. Thankfully the days of endlessly tweaking settings in renderers are over. I spent years learning first MR, and then Vray. To think of all those hours spent on an old, shit PC tweaking long into the night......

ozzman1997

musashidan said:

throttlekitty said:

nooo everything is next gen, forever! (it's a new thing to me, i've been on the 'old' mental ray in maya for years and i'm in love with this new stuff)

Question? Why not Arnold? Brute force Pathtracing is a lot more accurate than a 'hack' like FG. Thankfully the days of endlessly tweaking settings in renderers are over. I spent years learning first MR, and then Vray. To think of all those hours spent on an old, shit PC tweaking long into the night......

Is Arnold really that much better for this stuff than MR? 2015 doesn't have it but I can upgrade to 2018 if it's worth the hassle.