AO as a pass in multi-pass

[MJV]

I've put some tutorial files here (http://www.mvpny.com/AOtutorial/) showing how to do it as follows:

http://www.mvpny.com/AOtutorial/AOxAmbientmv.jpg

[STRAT]

hi

do as MVJ suggests.

another quick dirty (but highly effective) method i sometimes use is to render out your normal coloured image as normal, then apply a white self illumed material to the whole model and apply AO to this. then render this AO image out separately. then do your usual in photoshop with your 2 separate images as you yourself described above.

then in photoshop you can erase or rub out sections of the ao layer that dont need to show up (ie, ao in direct lit areas will be less than in shaded areas)

[govinda]

Also see these tutorials in After Effects and Shake (which I'm about to sit down and do myself):

http://www.tahlniran.com/

[Newstream]

Combining the AO-pass together with Sketch & Toon inside PhotoShop can also create some interesting effects.

/ Alex

http://www.badtastic.com/misc/aostexp.jpg

[gbie]

AFAIK there is no way to render both the picture without AO and AO layer at once. You will probably have to render them separetely.

If you use global AO, you can render the image or the sequence with the AO disabled first, then once again with AO and multipass. Combine the whole output from the first rendering and AO pass from the second one in photoshop.

If you use AO in diffusion, environment or whatever material channel, disable this channel in all materials and render. Then render appropriate material channel (via multipass). Combine the whole output from the first rendering and the material pass from the second one in photoshop. Beware that net render currently does not support material channels, you will have to render AO on a single machine.

In both cases there will be some overhead because you will have to render the whole thing twice. But as long as the AO is independent on material colors and lighting you can render the second pass without lights and with simplified material.

You can also consider reducing AA settings for AO, according to my experience it would not be very noticeable in the combined output. In this case the overhead will be lower, in the extreme case the total render time will also be lower. You can also apply a slight blur to the AO pass during postproduction if you find it too grainy.

[MJV]

Wrong. See my example for how to do it all in one render.

[sketchbook]

thanks for the help people. much appreciated

[gbie]

Wrong. See my example for how to do it all in one render.

You are right, obviously. I don't know why but I thought you had rendered your passes separately. I haven't seen your tutorial yet but looking forward to having fun with it.

Anyway, as long as I prefer to tweak AO settings for different materials in their diffusion channel, in this case I still can't find any way to render AO and non-AO layer at once. Does anyone see a solution?

What would definitely solve this issue for me would be an improved compositing tag with AO settings included. Then there would be no need to use AO in a material channel. Maybe in the next Cinema update ;) ?

[MJV]

Anyway, as long as I prefer to tweak AO settings for different materials in their diffusion channel, in this case I still can't find any way to render AO and non-AO layer at once. Does anyone see a solution?

Perhaps you could use object buffers to isolate individual objects and then use the individual object masks to determine what gets AO in post and what doesn't, and by how much, etc.

[jobes]

thank mjv for the tutorial files etc ... much appreciated :)

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