do you use occlusion

[bjeves]

Just playing around and testing an occlusion pass in using vray and am just wondering if many of you use a occlusion pass in your final images. It seem to take the flatness off the image producing more depth and contrast.

[signet]

ambient occ is vital!

 

to get the best out of the vray version make sure your falloff is set to 1.

 

when i say vital you could use detail enhancment in the renderer but that is slow etc

IF your doing alot of movie work then you will see the benfits of us AO.

 

here is how i use it.

 

Create a standard max material increase self illumination to 100

place vray dirt in the diffuse slot.

set the falloff to 1

set the radius as required.

setting it very tight gives good contact shadows and setting it wide gives it a skylight feel. (as i combine my AO passes in photoshops or fusion i do two passes tight and wide)

and over lay them both using multiply

 

 

so now you have a standard self illumintiang material and dirt in the diffuse slot.

In the render dialog under globals tick overide material and instance your new dirt material to the slot.

 

then do your tight and wide pass

 

and mask out areas in you 2d editor to create the look you want.

 

once you realise the power of AO you will never look back.

 

You can do whole aniamtions with moving objects and it NEVER flickers

[STRAT]

AO is an everyday staple in my imagery.

[manta]

Or you can use the Vray AO plugin...

 

http://plugins.angstraum.at/vrayao/index.htm

 

works great...and easy

[signet]

interesting that!

 

thanks

[bjeves]

thanks guys ive been trying that plugin and seeing much better results.

[innerdream]

I don't have Vray. In Cheetah there are two options AO or Radiosity and in the program Radiosity is the more physically correct solution. What is the difference in the way Vray uses AO? Curious...

[Claudio Branch]

 

ambient occ is vital!

 

You can do whole aniamtions with moving objects and it NEVER flickers

 

In your opinion, how important is AO when your subject is a large-scale outdoor scene?

 

Also, in regards to an animation of a large exterior scene, how should AO be used in relationship to rendered 3d grass (Hair/Fur), 3d trees moving in the breeze or moving cars?

 

All of these elements are issues in most of my projects.

[PGD]

Never used this before, but it does the job doesnt it!

 

Gonna try the plug-in... does that just do the seemingly simple task for you?

 

Renders quick doesnt it!

 

Do you still light the scene with a spot light casting a shadow (vray or area), then add AO ontop of it?

[Tommy L]

ambient occ is vital!

 

to get the best out of the vray version make sure your falloff is set to 1.

 

when i say vital you could use detail enhancment in the renderer but that is slow etc

IF your doing alot of movie work then you will see the benfits of us AO.

 

here is how i use it.

 

Create a standard max material increase self illumination to 100

place vray dirt in the diffuse slot.

set the falloff to 1

set the radius as required.

setting it very tight gives good contact shadows and setting it wide gives it a skylight feel. (as i combine my AO passes in photoshops or fusion i do two passes tight and wide)

and over lay them both using multiply

 

 

so now you have a standard self illumintiang material and dirt in the diffuse slot.

In the render dialog under globals tick overide material and instance your new dirt material to the slot.

 

then do your tight and wide pass

 

and mask out areas in you 2d editor to create the look you want.

 

once you realise the power of AO you will never look back.

 

You can do whole aniamtions with moving objects and it NEVER flickers

 

I rendered some stuff using this method; see attached

I like it. And its incredibly easy.

 

1 is with no AO

2 is with wide pass only

3 is with wide and tight pass.

[PGD]

Great examples for us!

 

Multiplied layers on top in photoshop?

 

I did this all the scene got darker, unlike just the shadow areas like yours:confused:

[Tommy L]

your ao pass should look like this

[BrianKitts]

Or you can use the Vray AO plugin...

 

http://plugins.angstraum.at/vrayao/index.htm

 

works great...and easy

 

5 STARS FROM ME.... I'll never play with AO any other way again!

[Tommy L]

Its a very efficiently written script, but the lack of fallof perameters make it fairly limited. The AO looks very uniform. I prefer Micheal Merrons' method with the material override.

 

Mind you, I was VERY impressed with the drag to window installation, that was refreshingly simple!

[signet]

In your opinion, how important is AO when your subject is a large-scale outdoor scene?

 

Also, in regards to an animation of a large exterior scene, how should AO be used in relationship to rendered 3d grass (Hair/Fur), 3d trees moving in the breeze or moving cars?

 

All of these elements are issues in most of my projects.

 

well AO will allow you to get around a whole bunch of problems. I never approach animations thinking I will be able to render everything in the one scene. I approach moving obects and grass in separte passes which may even be rendered using scanline or Brazil (AO will the be added to just those elements). Using mental prim/geometry and hair with MR AO is always an option and render that separtely with a view to compositing in Fusion or whatever.

 

I am pretty sure the Mental Ray AO renders quicker as well!

 

Trees render a full bright (beauty pass) direct light pass with some fill light, and AO you dont have to bother with indirect illumination.

 

you can also use it conjuction with lights. Maybe even put it in a Falloff using shaded/lit to experiment with effects.

[Claudio Branch]

 

well AO will allow you to get around a whole bunch of problems. I never approach animations thinking I will be able to render everything in the one scene..

 

I use Adobe Premiere and I have typically rendered out entire scenes in just one pass. Composisting is not on my resume at present...

 

I will have to find some crash course tuts I suppose!

[Stephen Thomas]

Great examples for us!

 

Multiplied layers on top in photoshop?

 

I did this all the scene got darker, unlike just the shadow areas like yours:confused:

You need to reduce the layer opacity, I usually find a value of about 35% is good.

[Trevor Tizard]

Please excuse my ignorance.

 

@Tom: in your examples are you still using GI in the renders, and if so is it just on a very low setting. Perhaps you'd be kind enough to expand on the methods.

 

I'm affraid I still don't get wheather AO is used instead, or as well as GI.

 

Thanks

 

 

 

 

Trevor

[Tommy L]

There is no light in the render at all. Turn off lights and GI. What you are rendering is a gradient terxture based on proximity of geometry. Thats what an AO pass is. Your rendering a pure texture on geometry, theres no need for light because there is no need for shadow. You are SIMULATING the effect of AO using dirtmap shader.What you are telling the renderer is

 

"point A is at edge, Point B is not at edge. Mix swatch A and B across point A to point B".

 

Now if swatch A is Black and swatch B is white, you will get something like the renders in the earlier example. But the swatches could be any texture/material within the dirtmap. If swatch A was a grimy dirty rusty material and you had complex geometry, it looks like there is gunk thats gathered in the crevices, hence the name, dirtmap. Its alot simpler than it sounds.

If I get time later Ill post a screengrab of the file if I still have it.

[PGD]

So do you render the scene with GI, lights etc first... then overlay the AO over that?

 

Thats how I understood it and tried the other day anyway

[Tommy L]

Its a flexible tool, you can use it how you like, but yes thats what I did.

[Trevor Tizard]

Its a flexible tool, you can use it how you like, but yes thats what I did.

 

As I thought........!

 

But, was the GI in the first image on a fairly low setting as you could then use AO to enhance it?

[Tommy L]

yes. But some people also use it so they can have an incremental irradience map, exclude any moving objects and use the AO instead. My feeling is it gives greater control over ambient shadow depth and its a bit cleaner than GI. Its not an accurate solution for lighting, but it contributes a controlable depth value if used in combination with GI.

[Trevor Tizard]

Thanks very much Tom.

[ctk111]

Is anyone familiar with how to use this with the physical camera? If it's not possible is there a way to convert a vray physical camera to a standard max cam? I see there's a script to convert a standard cam to a physical cam, but I didn't say anything about going the other way.