Ambient Occlusion - I like it! now what?

[heyvern]

 

Okay, I did my VERY FIRST AO RENDER! Woohoo! Straight out of the box. It isn't fantastic but i get the idea. Now I want to know what the next level is. How would I for instance, use some kind of image for reflection? Is this delving into the HDRI concept? Radiosity? AO renders SO FAST, I don't want to get too complicated.

 

Can I use just a simple dome with an image?

 

Anyway, this sample image is from my ongoing animated short spoofing the terminator (not much activity in Vern's World so this is a tease looking for some help on AO. The link to this thread is in my signature) Just for grins I stripped out the lights, added a ground and back plane and just rendered it with 30% AO. Not bad for the first time. The ground and back plane have "cast occlusion" off. I assumed this is correct? They don't "cast" they "receive" right?

 

I like the potential but of course it is reflecting all the "white". I have a material with an environment map on it (along with 97% reflectivity), but it seems to be overpowered by the white reflection. Can I use some sort of "HDRI" image? Does it have to be in that format? Would it be better to use lights and lower the ambient percentage?

 

Is AO sort of a "one trick pony"? Do I need to move on to radiosity rendering? (AAAAHHGGGGG! That scares me!).

 

I'm kind of excited about the possibilities, and I feel I'm acting like a gung ho noobie. I am just experimenting at the moment.

 

-vern

[robcat2075]

Maybe what you're looking for is "IBL"... Image Based Lighting. Sometimes mistakenly called HDRI.

 

Haven't ventured into it myself yet.

[heyvern]

Yes, my mistake. IBL. I'll do another search on the forum.

 

What I'd like to do is possibly... use a prerendered image of the "scene" to map onto the characters. Then I could speed up render times by using compositing rather than render everything in one shot using reflections. I could render the characters completely separately from the back ground and other elements and composite. The only reason I am even considering this is that on my piece of crap PC the AO rendering was quite fast (Yes, it was a small render, with a low AO percentage, and not really really fast but still faster than I expected on my clunker that barely works.) so I can only imagine how fast it could be on a really good computer. The added "coolness" to the look might well be worth it. I would love for this to come close to or even rival the final quality of one of the Terminator movies... doesn't have to of course, I'm just thinking out load at this point.

 

-vern

[John Bigboote]

AO renders SO FAST, I don't want to get too complicated.

-vern

 

How fast did it render for you?

 

I have been rendering a :10 D1 res animation for the last 2 weeks...it's 80% done at 1hr 20 min per frame.

 

What I don't 'get' is the preview render (shift Q) gives a nice quick visual of the AO effect, but the 'real' render seems to get stymied with calculations... sure the results are quite cool but....

 

I'm glad you think it's fast.

[heyvern]

I rendered at 800 x 600 with 30% AO and 3 passes. It took 20 minutes on a machine that is more than 5 years old, has 600mb ram and a 1.3ghz processor. I suppose I should test something more advanced on a faster computer to be sure. I keep forgetting that bumping up some of the settings is probably going to be a "geometric" increase in render times.

 

Do you think I'm crazy to go this far with it? I tend to get carried away.

 

-vern

[zandoriastudios]

You should have the ground plane cast occlusion, otherwise your global ambience will be coming from below as well. I would also increase the occlusion to 100%.

Use an image instead of Global color for your ambience, and you can light your scene with just that (no lights required).

 

The Occlusion sampling (render properties) is where the time hit comes in....20% is the default, but you can go up to 100% or as low as 10% (grainy).