LightWave - Tutorial: Occlusion made easy

[Meurig]

Occlusion renders for beauty shots are always nice because they're great for showing off detail. Here's a really quick and easy way of doing it in LW 9.0+ using nodes. My object, scene and materials are in the attached rar.

I'm not sure how to go about uploading tutorials to the resources, but if this is helpful enough to spread I'll do that too.

Enjoy.

Occlusion made simple

A quick and easy way to set up nodal occlusion renders in LW 9.0 and above. For this tutorial I will be using LW 9's inbuilt nodal occlusion shader rather than a third party plugin like SG_AmbOcc (which is also good).

Step 1

In modeller prepare your object. For the purposes of this tutorial the entire object will use a single surface, but multiple surfaces can have different occlusion with different settings if you wish. I have called my surface OCCLUSION and applied it to my object, which is a just a couple of primitives resting on a plane. You can save this separately from any surfaced version you may already have. This is not always necessary, you may choose to apply the occlusion shader in Layout and render it, and then close layout without saving changes so that your model reverts to using it's usual textures. The only downside is that you'll have to set up the occlusion shader again should you want to do another Occ render and you risk hitting save out of habit

With the model saved as, for example Object_Occ.lwo, it's time for....

Step 2

Starting with a blank scene, import your Object_Occ and position the camera so you can get a good view of it. It doesn't matter where the light is because we'll be deactivating it later.

Step 3

Open the Surface Editor and find your occlusion surface. The only changes from Lightwave's Default surface that I have made are to make it slightly more diffuse so that the dark areas the occlusion creates aren't quite so dark, and made the surface colour completely white so that the occlusion's contrast is more evident. Neither of these changes is really necessary, but I find it creates nice results. Make sure the little tick box beside the big Edit Nodes button is active, if this box is not checked the nodes will have no effect.

Step 4

Press Edit Nodes and we go into the Node Editor. You will see a large bar called Surface with lots of multicoloured circles on it, this is the surface that you want the nodes to affect and any changes you make will plug directly into it. Press the Add Node button in the top left of the window, and navigate down to Shaders>Diffuse>Occlusion. A new Occlusion node will appear, click on it's green Out icon and drag to the Luminosity channel of the Surface node. This will plug the occlusion node directly into your surface's luminosity meaning that the changes that the occlusion makes will affect how bright your Surface is. For the purpose of this tutorial this works fine, but if you want to include Occlusion into a surface that has other inputs it would be best to plug it into the Diffuse channel for realistic effect.


Note. - Don't be fooled into thinking that Occlusion II is a newer, better version of Occlusion because it isn't, it is in fact a shader for Reflection Occlusion which is something entirely different. Reflection occlusion colours your object on a grey scale depending on how much the surface has to reflect. Ie, if you put a box on a plane and set the plane to recieve reflection occlusion, the reflection of the cube on the plane will appear black while the rest of the plane will appear white. Personally I don't think Reflection Occlusion is something people will use very often and in anything other than compositing. Calling it Occlusion II was just misleading naming practise on Newtek's part.

Step 5

Double click the Occlusion node to bring up it's options. The Samples field determines the quality of your occlusion, the higher the figure the nicer it will look. Also the higher the figure, the longer your renders will take, so it's worth finding a balance between the two that you like. I tend to use between 20 and 30 samples. The Mode menu lets you choose between Infinite and Ranged. Infinite means that any traced ray hitting a polygon on your model will bounce and be calculated for an infinite distance from that bounce before hitting another polygon. Setting it to Ranged allows you to limit the distance that your rays travel and can be used for specific effects or to speed up rendering. I tend to leave it on Infinite. Close the Occlusion settings and the node editor.

Step 6

Select your camera and edit it's properties by hitting p or the Properties button. My image shows a quick quality setup which suits these renders fine. Personally I would recommend using FPrime for occlusion renders because it's faster than the native Lightwave renderer, and you can save and cancel the render at any time at any quality level that you think is good enough for what you need, rather than only being allowed to save when Lightwave allows you to. If you don't have or don't want Fprime, these settings will do fine.

Step 7

Select your default scene light and bring up it's properties. Turn the Light Intensity to 0%, and the Ambient Intensity to 0% as well. You don't need this light to affect your model since the scene will probably be quite bright anyway. You can of course use it if you want to and it's worth experimenting with, but it's the occlusion that's going to highlight your model's detail rather than the lighting. Similarly for the ambient lighting, you can raise that if you like but it tends to negate the Occlusion's effects to an extent by making the scene brighter universally.

Step 8

Close the light properties and you're ready to render. Unlike radiosity, Occlusion isn't affected by the background colour because it's a shader rather than a lighting effect. This means that it changes the way a surface behaves rather than the way it's lit. You may choose to use different coloured backdrops for additional effect though as the below black and white backdrops demonstrate.

You can save your occlusion surface to a backup if you want to keep and reload it later on by selecting it in the Surface Editor and going to the save button. I've included my saved surface in the attached archive as well as all the scene elements I used. When applied to more complex models the render time will obviously increase but for hard surface work especially Occlusion can be a very effective way of demonstrating the detail that your model has, and allowing people to see your work without complex light setups or large swathes of your scene being obscured by ugly shadowing.

One of the great things about nodal occlusion is that you can use it to accentuate your surface rather than override it for more realistic looking results. Just plug the node into the diffuse channel of a normal surface and it'll do it's job in the background. The render times will climb but the overall effect is worth it.

[Oscaron]

Thanks much for the knowledge-share M!

[Gordon Robb]

Thanks Rhys, I never really got my head round this with nodes. Least now I'll be able to do occlusion with fPrime.

[Rigel]

Nice piece of work Meurig. Thank you for sharing.

[hemimotorz]

Thank you for the tutorial! Very nice work.

[nikfaulkner]

cool thanks a bunch

[winddelay]

I've really got to learn how to do this. Great tut.

[Lemon Wolf]

Thx for sharing this

[Nadesico]

Effective tutorial. I never really bothered setting up anything like this for my models... probably because they never get to the detail stage in the first place

[Meurig]

Mattman has kindly uploaded this tutorial to the resource section for more obvious and easy use It's easily found via the Resources>Tutorials menus.

[Oscaron]

Originally Posted by Meurig

Mattman has kindly uploaded this tutorial to the resource section for more obvious and easy use It's easily found via the Resources>Tutorials menus.

LOL...Love the new avatar

Meow Tse-Tung??

[Meurig]

Chairman Meow

[tommywright]

I'm getting a lot of noise this way.. is there a setting I can raise to smooth this out? Your renders look really good.

[Meurig]

Either up the samples in the occlusion or if you're using fprime just let it cook a bit longer My example shots there are both fprime.

[tommywright]

Which version of Fprime works with 9.2? I got my 1.02 working but it's ignoring the nodes I set up. Is there something in Fprime to make it see nodes... or is my version too old?

[Meurig]

Yeah the version is too old I think. Should have mentioned that I suppose... 3.0 supports nodes, I don't know if the 2.x series does or not.

[MooseDog]

the native lw solution is to "up" the adaptive sampling to .02 (while lowering the aa to 2). make sure to change the sampling pattern to "classic". also, assuming a real-world scale for your models and scene, up the "minimum evaluation spacing" for your interpolated final gather radiosity to >300mm.

[Meurig]

Ahh no, you don't need radiosity active to get occlusion working. Having it and occlusion active at the time is a surefire way to make your renders take forever. I'm sure the AA and AS bit is valid enough though

[MooseDog]

oops good catch. shoulda paid closer attention to what you had written in the first place!

[Escelce]

Always wondered how your "clay shots" looked soooooooo good. Great tutorial and thanks for sharing my friend.

E

[FlangEG]

what about an enclosed room, such as this cubic room i made based on "Cube^2"
I'm having difficulty to get lighting effect of the walls while simultaniesly getting shadows from the ladders.

[Meurig]

What about it?

The only real difference you'd want to change is the distance setting in the occlusion options if your normal occlusion renders using the above method aren't working. If you leave it set to infinite your room will be completely black. I don't know what scale you've built your model to but if you set the Ranged distance so that it's only set to affect a short distance from the edges of the rooms it should look decent.

If that's not what you're asking I'm not sure what you're getting at. Your question is pretty vague

[FlangEG]

tnx, it helps

[Patrick_G]

Hello there,

Thanks, for this help.. & your website is an inspiration too !

Patrick_G

[Rigel]

Originally Posted by Patrick_G

Hello there,

Thanks, for this help.. & your website is an inspiration too !

Patrick_G

You're welcome.

And welcome to Foundation 3D!

[Treybor]

Sweet! Thank you!

[HBOMB]

Just wanted to say thanks. Also, its great to have found a site where the members are truly passionate about helping others to find the knowledge, and offering thier own experiences that others can get the results they are seeking. I've been to many sites only to leave because of the egos involved. I don't think I can stress, or say thank you enough what a great service you guys are providing.

[miturner70]

I used this tutorial and thank you it is awsome my only question is how to I get rid of the graininess in my render?

[Rigel]

I just realized that I can finally try this now that I have LW v9.6.

[Meurig]

Originally Posted by miturner70

I used this tutorial and thank you it is awsome my only question is how to I get rid of the graininess in my render?

Raising the samples in the occlusion node will increase the occlusion quality It'll also lengthen your render times though, so be wary of using overly high figures.