* * Poser Multipass Render Tutorial * * by PhilW
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No AI - This artwork was created entirely by hand or with traditional digital tools.
Description
I received a couple of questions about the "Multipass Render" technique that I used in my last post so I have put together a little tutorial which I hope is helpful.
Some programs (eg. Vue) have a multipass function built in, but you need to do it manually with Poser. This sounds time consuming, but it can be an effective way to combine different processor intensive render effects into a balanced final picture without endless test renders. In this picture, I wanted to use both volumetric light coming through the window and also IBL with Ambient Occlusion for the ambient light in the room, and I thought it could take forever to get the balance of lighting and effects right.
So I rendered three times - once (1) with just the light coming through the window with no atmosphere. This gave a high contract look with no ambience in the room, so there were areas of complete black where it was in shadow. The second render (2) had the volumetric atmoshere set quite high (still just the one light!), so it was mostly the rays of light coming into the room (and some artifacts in the shadowy areas that I could block off later as it was separate!). The third render (3) was just with a single IBL light that looked quite flat but filled the room with light - this last render took the longest, several hours I so left it running overnight.
The next morning, I combined the three using layers in Photoshop and Screen mode for each layer so that they added together. By playing with the opacity of each layer, you can visually balance the different lighting effects to get the final version. Easier than having to adjust lighting and keep re-rendering each time, as you can do it interactively and instantly see the results!
For this it was (1) 80%, (2) 15% and (3) 15%. I also used a layer mask to remove the artifact areas from render (2). But obviously this will vary with the picture that you are doing and the effect you are trying to create. A tweak of overall levels and contrast and it is done.
I hope that this is useful and gives you some ideas to try - let me know! Thanks for looking, have a great weekend. Phil.

Comments (8)
Very nice render and a useful explanation. Thanks for sharing!
Multipass to Pay, in Poser 7, it is in the command Scripts, and it works quickly. But of any it sorts things out, it is another solution;. Belissima obra, aplausos (5)
Great explanation...thanks. Not sure I'll ever find the time to try it out, but well worth knowing. :)
Fantastic made and a great explanation!!!! Thnak you Phil for this tutorial!!! Hugs Ute
I'll have to say it again! I admire your patience with renders! :) Coming from a straight P4 engine renderer here as I can't stand waiting for ever on anything to render! :)
WOW Phil!Thanks for shearing it!
I like how 1/2 or so of the picture is in darkness, but you can still infer it. Makes the composition interesting. Thanks for the tut too!
Thank you for the tutorial, Phil!