Anatomy and Art

a blog by Sara Egner

Archive for the ‘ambient occlusion’ tag

Still Going With It…

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Feels like I’ve been spending all this time at the computer lately, but not as much time posting here.  That could just be a perception thing, but I thought I’d post another image from my animation anyways.  This is an ambient occlusion pass from my recent work.  It features the plates and screws in place for both the BSSO and osseous genioplasty procedures.

At present I am struggling with making the screws enter the bone in a reasonable manner.  They are happy to rotate all over the place, but I am having a Hell of a time getting them to simply screw in here.  The still looks nice though.  And the motion will come.

I’m actually very close to finally getting through my shot list for this animation and being able to put the finishing touches on it.  Keep your fingers crossed for me readers, I need all the luck I can get with this one.

Written by Sara

April 24th, 2011 at 4:15 pm

Still Shot from Working with my Animation

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Just working with my animation footage in After Effects this afternoon, and stumbled into this image.  Thought it was pretty cool and worth sharing.

That comes from layering the ambient occlusion pass of my shot with the skull set to multiply and 40% opacity, over the shot of the soft tissue in the same position so that it ghosts the underlying anatomy.

Pretty neat!

Written by Sara

April 16th, 2011 at 2:25 pm

Setting Up Ambient Occlusion in 3DsMax

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If you are anything like me, you spend a lot of time trying to remember how to do things.  Because I rely on them so heavily, I thought I’d try my hand at posting some instructions on setting up an ambient occlusion pass in 3DsMax.

So, first of all, for those of you who have no idea what I’m talking about, an ambient occlusion pass is a nifty compositing trick wherein you render out an image, or series of images if you are making an animation such that objects closest to one another create shadows between them.  It’s the kind of touch that can really sell the look of your objects all being in proximity.  By itself, an ambient occlusion pass might look like this…

Which is neat and all, but actually gets useful when laid over your standard rendering, or beauty pass (see below)

(without ambient occlusion pass)

(with ambient occlusion pass)

So wow, that’s amazing, right?!  And even if you don’t think it’s amazing, maybe you still think it’s nice and maybe you want this for your project too.  It’s actually even cooler if you are rendering out a room, or some sort of scene with lots of objects.  You’ll note that my background remains blue throughout these.  That’s because I set my background that way in 3DsMax’s render settings and I’m not using a backdrop in this scene.

So, get your scene going in 3DsMax.  That part is all up to you.  Again, the more stuff, the more fun this is.  Then press the M key to pull up your materials window.  Fantastic.  Now pick an empty globe up there to make into your ambient occlusion material. Go ahead and give it a name too.  In my case I went with Amb Occ.  Next to your material’s name, there should be a button that says “standard.”  Go ahead and click that and under the Mental Ray texture options, click Mental Ray.

Next you’re going to click on the button that says “none” in the basic shaders next to where it says “Surface.”  Select Ambient/Reflective Occlusion.  At this point, your globe should look like a solid white ball.

Keep that window open, but go ahead and open up your render setup window as well.  Under the processing tab, check the box to enable material override (see below) and you can literally drag and drop your ambient occlusion texture into the box next to where it says “material:”.  That overrides all the materials in your scene with the one you’re creating now.  This is especially cool because if you want to go back to your original textures all you have to do is uncheck the box, and bingo there you are, back in your scene just the way you left it.

If you render at this point, chances are that everything, or near everything, will be white.   That’s not very helpful, so go ahead and get into your parameters and change the Max Distance to a higher number (see below).  I am using 100 as the max distance with my own ambient occlusion pass at the moment (yes, I am literally writing this while I’m rendering a shot, ‘cuz y’know, it was on my mind).  Now, try rendering again (either by hitting the render button, or by hitting the F9 key.)  Is it everything that you’d hoped it would be?  If not, maybe try adjusting to different numbers, or experimenting with the other parameter options.

And there you go.

Now it’s up to you to decide how you want to use it in either Photoshop or After Effects, or another similar program.  In general, you’re looking at stacking layers, and setting your ambient occlusion pass to the multiply setting, so that only the shadows come through.

Enjoy and good luck!

Written by Sara

April 11th, 2011 at 8:17 pm