Bake Ambient Occlusion with IvyGrower

[Brian Jones]

how big did you make the texture? In the ivy object all the leaves are one object (well, one for the young leaves and one for the old leaves) and one texture map has to cover the whole surface area of all those leaves, so it would have to be big enough for detail. That goes for the color and the AO. It might be better to check out the help for AO and tweak the settings for speed (unless you are there already)

[Chris Wood]

Sorry, I’m not following you for what I should do here.

I emailed the guy who made it and he got back to me with this:

“Hello Chris,

A couple of things to help bake the ambient occlusion:

* Add Ambient Occlusion to your Render settings (under Effects).
* Enable Diffusion on the Materials and set the Texture to Ambient Occlusion (under Effects again).
* On the Bake Texture tag, enable Ambient Occlusion, set SuperSampling to 1, set Background to black.

I went with the default 256×256 in PSD format but you can try different sizes and formats.

After you bake the texture, replace the Ambient Occlusion shader on the Diffusion channel with the resulting baked file. You can also disable Ambient Occlusion in your Render settings at this point. This greatly improves render times.”

This seems to be a step in the right direction, however, it still looks nothing like actual AO, and still has weird glitches over some of the textures.

[Brian Jones]

Don’t have time to test but Baking has a bunch of settings which will change things and I’m most familiar with baking when it moved from the Render Menu, either the Bake Texture tag or Bake Object in the Object menu (12 and 13?). Either way regardless of other settings baking will produce (at least with the ivy leaf objects) one of two kinds of images. If you include all the layers available with one method you get what looks like one leaf which since that is how the leaves are being done (single image provides the colour for all the leaves) looks fine but the AO (or diffusion channel) is having to be used for all the leaves so it can’t be right to use the same AO for everything. The other method gives you an UVW mapped image that has many leaves on it, the individual leaves in the image are UVW mapped to an individual leaf in the leaf object and potentially could have the correct AO across one leaf but for this one image to have the correct detail for so many leaves means it has to be *huge*. It takes a lot longer to make an image that size and it might be quicker to just render with AO, so that’s why I thought it might be better to just use AO in the diffusion channel of the leaf objects and tweak the settings of the AO for speed.

[Chris Wood]

I broke down and rendered with AO on for one of the scenes (1:10 seconds for 137 frames which isn’t too bad) but I have another scene with 280 frames, 6-7 minutes per frame, which is very bad.. Over a day of rendering. My PC will asplode!

I’ve been trying to get this to work nearly all day and just can’t. Surely there’s an easier way? Rendering AO just the once is 6 minutes. After that there’s no change on the texture as its just the cameras perspective that’s changing.

Thank you.

[Brian Jones]

I don’t think you can bake AO successfully with this object, it works great most of the time and it would work great if the leaves were all separate objects (thousands of them with thousands of separate textures)…

The quickest render method I can think of that would be sort of appropriate would be to use Fresnel (you’d want to invert the knots in the fresnel so it was black on the left of the gradient and white on the right) in the Diffusion channel instead of AO, the result would not be as ‘real’ as AO but would give you, hopefully, the leaf definition you are looking for.

[Chris Wood]

I’ll give Fresnel a try then, thank you.

Yeah it’s just the main thing of trying to make the leaves look more real, that’s all.