Problems with depth of field render with HAIR module

[Brian Jones]

Depth in a multipass render does not include post effects, only depth information of non-post effect objects. You can see the information in use if you activate Depth of Field in the Render Settings/Effects tab and set the settings there, that results in a blurred image that you see in a normal render – which in a multipass render is either the Background channel in a multilayer file or the RGB image in an image-per-layer render. If you don’t turn on Depth of Field in the Effects tab the rgb is not blurred but the depth information is still saved where you can apply it to whichever layers you want at whatever strength. Which is why Depth is a Channel in a multilayer file and not a Layer (easier to take a selection from (well in PS for sure, I’m not an AE guy)).

[Honza Maštera]

Thanks for explanation 🙂

If I get it right, I cannot use HAIR module together with DOF because HAIR is a post effect module and applies itself after the DOF has been applied to the non-effect parts of the scene. Right?
Can I cheat this somehow? Like convert the hair (grass) to polygons? That’s crazy isn’t it?

[Brian Jones]

Yeah, if you choose any of the poly options in the Hair’s Generate tab it will show up in the Depth channel. Don’t even have to make it editable. However you will have to retexture it since the Hair material won’t work anymore. Just depends on whether you have enough memory/horsepower for the amount of grass you have.