Ambient Occlusion Shader

[Jure]

Anyone tried this plug for interior scenes? I tested it a bit and it looks very promising. Here's a sample. I rendered it in layers: color pass, shadow pass and ambient occlusion pass. Combined in photoshop.

 

Anyone else have any experience with it?

[kicks]

[Jure]

Well I don't know how much time I gained this way because this was just a quick test. But it's definitely much faster than using radiosity. And it does give you flexibility to adjust each pass in post process.

As I mentioned I rendered this image in passes. But you don't neccesarily have to do that, you could as well just add AmbOcc Shader and render everything in LW. Rendering in passes gives you that fast and easy fine tuning ability though.

[IC]

Thats interesting-I'm just about to try it.

Your render looks really good.

[IC]

Finally managed to spend an hour trying this out.

 

The first render is done with area lights and very low quality radiosity-10.5 mins@800x600.

 

The second is done with point lights and no radiosity with the Shader applied to a few materials. Ambient is turned up to about 65%.

This took 28 mins @800x600!

I like some things about it mainly the shadows around the plant and picture on the far wall.

 

I got a soft shadow pass in about 10 mins using the Shader but I'd still have to do the main render after that so although its a useful plug in that does exactly what its supposed to, I can't really find much use for it in my workflow.

[IC]

Been trying this out some more.

 

The shader isn't much quicker than high quality radiosity but I really like the effect on interiors.

Gives a really nice darkening where surfaces meet that radiosity doesn't always provide.

[kicks]

http://www.cgarchitect.com/vb/showthread.php?t=7062 on similar shader for max mental ray. I have been using the same & similar workflow since & am completely happy with the flexibilty it offers.

[IC]

That's a great image for 3 mins!

 

I'm just using the shader on the materials I think would be appropriate after setting up the scene for standard lights.

It's quite slow, even on it's own, so using it to obtain a shadow pass and then doing the other passes doesn't save me any time (but it does offer flexibility).

 

In LW you apply a shader to a material rather than to a channel. Then you can open up a separate interface to alter each channel, as required.

 

Looking at your images and your render times, I don't think you need to learn anything from my process

[kicks]

[Jure]

I'm doing some test renders right now, because I belive the shader has more to offer than it has been demonstrated so far... I'll post results later. Currently waiting for radiosity render to finish :/

[Jure]

Okay, here are a few tests:

 

1. Interpolated radiosity: 6.7 sec

Settings:

Intensity: 300%

Rays Per Evaluation: 10x30

Indirect Bounces: 3

Tolerance: 0.3

Minimum Evaluation Spacing: 3 m

 

Not realy looking that nice realy, it's useful for stills but not for animation because of splotchiness.

 

2. Monte Carlo: 45m 59sec

Intensity: 300%

Rays Per Evaluation: 3x9

Indirect Bounces: 3

 

Nice but blotchy... I would need to up the rays per eval. to get rid of the splothces. Not usefull for animations because of long render times.

 

3. FPrime: after 20 mins

Monte Carlo

Intensity: 300%

Indirect Bounces: 3

 

Same as above...

 

4. Ambient occlusion shader

No radiosity only couple of spot lights (no shadows) and one Area light (raytraced shadows) acting as a window. Rendered in two passes:

Ambient occlusion pass: 2 min 1 sec

Everything else: 1 min 2 sec

The two renderes are then comped in Digital Fusion.

 

Very useful for animations IMHO!

 

Cheers!

[IC]

Nice work Jure.

Hope you don't mind but I've copied your scene and tried out a different set up.

 

Spotlight(sun) outside and three area lights (no shadows) on window, floor and ceiling.

 

Two point lights to simulate colour bleed from the red and blue objects.

 

1 minute 45 secs for a complete 640x 480 render.

 

For stills, switching on interpolated radiosity with really low settings took it to 2 minutes. Warms it up a bit.

 

What are your settings for the shader-your shadows are very soft.

[Jure]

Hey... My settings are rays: 25 shift: 0 lenght: 1m, everything else on default. But I use area light as a window that casts soft shadows hence a little longer render time then yours.

You should raise the shift value in your shader because your shadows are way too dark - or render separate pass and comp it.

 

In any case I find this shader very useful and I won't be using radiosity for quite some more time I guess .

[IC]

Thanks Jure

Changed the shift to 0 and got a much nicer result.....

[Hector]

Just a couple of questions:

 

How do I render separate passes in Lightwave?

 

How do you deal with reflections?. Rendering reflections slows down my renderings a lot when I have large amounts of reflective surfaces (usually glass). And I am not even talking about radisoity. There were no reflective surfaces in your examples.

 

Thanks

[IC]

The easiest way I have found to do it is to create a version of your model with no textures. Then render without raytrace reflection etc but with the amb occ shader applied.

This gives you your soft shadow pass for compositing over the other pass(es) in post.

 

Reflections do slow things down. F-Prime helps.

[Jure]

There's a couple of ways of rendering in passes. One is by applying Render buffer export Image filter plugin, the other by using PSD export image filter. This two doesn't give exavctly the right passes but are the fastest to set up. The third is to do everything manualy. This is done by modifying each object surface properties as appropriate. There is a checklist for help you doing this here: http://www.g-3d.com/Newer_AAC_3d_multi.html.

Here's a nice basic multipass tutorial:

http://www.lightwaveoz.org/tutorials/multi_pass.php

 

Everything involving raytracing is very slow. Reflections are always very heavy on render time. Try using as low "Ray recursion limit" in render panel as possible (instead of default 16). There's also a plugin by Evasion3D called hypersmooth that speeds up reflection rendering quite a bit.

[IC]

Another way is to render your ambient occlusion pass on textureless objects then insert that image as a front projection map in the diffuse channel of the textured version.

Then just render the way you normally would.

 

The results are great and it cuts out photoshop.

(Only for stills though!)

[lup]

I m sorry but where can i find this Ambient occlusion shader???

 

Thanks

[IC]

Try http://www.Flay.com for all LightWave plug-ins.

[otacon]

Ive been playing around with this shader for a day now, and its pretty sweet. I dont have the option of radiosity for my work, so this shader works great for me. I like to keep the shift >1 most of the time. That way its more subtle and not too dark in the corners. I also try to keep the rays below 14, turning on shading noise reduction can clear up any grain.