Render elements for glass

[tricky]

Render elements and compositing of them has been covered quite a lot, (and embarrassingly, I've rarely had much success with it myself) but I can't find anything specific to this.

Example: I have a scene of a building and I am producing an exterior view. There is quite a large glass facade, with furniture etc behind the glass. What I want to do is render the scene, but somehow have the glass 'elements' seperate so that in Photoshop, I can place people etc behind the glass.

Is this possible in a one-click process? I seriously doubt it, but what is the next best thing (which elements and which order) to isolate the glass reflections/transparency so that they can be added on top of the layer stack in Photoshop, with all the 'interior' people behind it? I want to use the 'rendered' glazing as much as possible, so the reflections of other geometry on the scene plus any HDR or Vraysky in the environment.

(Historically, I have always 'built' the reflections manually in post production from a 100% reflective/opaque layer mixed with other bits of sky etc glass mattes, reflection mattes and the like, making them transparent and dropping in people etc behind. This works most of the time, but with complex projects with many buildings and lots of glass facing different directions, it starts to get complicated. I am now looking at a pipeline where we can get more out of the rendered glass reflections of the rest of the scene/environment that we build within 3dsMAX)

I apologise in advance for certain bits of this thread crossing over other threads on the forum, but I can't find a specific thread despite looking at length.

[RErender]

Should work to render a reflection element and just add it to your people layer, and adjust the hue and tint to match what the glass might do, if you need to mask walls and mullions from the people use a multimatte(s) with id's set for anything that will occlude them

[m_hinks]

Historically, I have always 'built' the reflections manually in post production from a 100% reflective/opaque layer mixed with other bits of sky etc glass mattes, reflection mattes and the like, making them transparent and dropping in people etc behind.

Arrr I see we might have been from the same school of thinking! Nick P taught me well! and I am still using and showing people the method as it allows such full control in post.

I have been finding that its hard to get round this. Unless your working in 32 float PSD files, you cant properly layer render elements. I have played with comping all the elements in a psd file, as 32 bit, then saving and importing it as a smart object to a 8bit PSd file. It works, and means you can always click in to the 32 bit file and play. BUT the file sizes of the 8bit file get pretty damn big!

Id be very interested if you manage to work this out. Two heads are better then one after all!

[RErender]

Of course you need to work in float, doesn't everyone by now? well 1/2 float is probably enough...

[m_hinks]

Well ofcourse for animation! But with stills Apart from the renders, not much else in terms of people, cars, or vegetation are in 32 bit. That's why a 32 bit smart object works so well