Multi-pass and g-buffer

[MTM]

I am trying to use mult-pass and or g-buffer from Vue 7.5 in AE, but it is not obvious how to obtain the same results as a color pass. An explanation is lacking in "from the ground up" and I can't find any tutorials. A few paragraphs on the technique would be very helpful.

Thanks,

Mike

[Amka]

Hi Mike,

Sorry for the time it took to reply.

Saving in G-buffer and Multi-pass are slightly different things. Which one you use depends on the information you're trying to save with your files. I have to admit I'm not very adept with After Effects, and beyond the files that Vue gives you, I may not be able to give so much advice. Vladimir, however, has used AE quite a bit and is following this conversation. Also, if I'm saying anything you already know, please forgive me. This might answer someone else's question later on so I like to cover things thoroughly. And if I don't answer it, give me a holler.

The G-buffer will give you the kind of information such as normals, material ID, transparency, etc that is common when 3D artists are porting their rendered footage into software such as AE. This information in channels so you can access it while working with AE. In the Render Options,to use the G-buffer you must have either preset render settings higher than preview or analogous user render settings. With that set, in the bottom left you can enable the G-buffer. Now click the edit button to open it up, and you'll see the different channels that the G-buffer can save. Select the ones you want to use. Now at the bottom of the G-buffer options, you will need to save this information to disk if you want to use it in AE later. So enable that option and then click on browse to save the file with the name and type you want. There are two different types of files for saving G-buffer information. One is .RPF and the other is .RLA. Now the important thing to understand is that this won't be the only file generated when you render. Click OK on the G-buffer options. Now, you'll also need to set the Render destination. Set it to Render to disk, and then in the options you'll be able to browse and name the color picture as well. Keep track of where you've saved both files.

Now, when you open After Effects, you can import them both. You'll have a color picture and the G-buffer file.

Multi-pass is similar, except that there are a lot more options to save and you have the choice to save all this information as separate picture files or as a single .PSD which AE can also handle. Once again, you'll need to select Save to disk and then choose either multi-layer psd or separate files. You'll want to click the browse button to name it. And if you've chosen a PSD you also have the option to embed alpha information. This may or may not be useful to you. Once again, both the jpg and the psd will be generated, but in this case the color picture will also be saved as the background layer in the psd file.

I have only worked with multi-pass files outside of Vue. But even so, you should be able to find some tutorials about rpf/rla files in AE.

Hope this helps and good luck! If you have any other questions, don't hesitate to ask.

Cheers,

Ami

[MTM]

Thank you Ami,

I will look for tutorials on rpf/rta with AE and let you know how it goes.

Thanks,

Mike

[MTM]

I found quite a nice tutorial on RPF at http://cgswot.com/tutorial/tutorial_12_pt1.html and was encouaged that I had found what I need, but in the end it was incomplete.

Many of us doing animations have struggled with long render times and I have spent countless hours trying to optimize my renders. In particular, I have a desert scene I made in vue 7.5 with 58M polygons that requires a 3+ hour render time per frame to reduce flicker. I found that flickering was mainly in the sandy terrain part of my scene. So, I found, if I just rendered it (minus the ecosystem) I could render it at 10 minutes per frame with a high level of anti-alias. The ecosystem required about 30 minutes per frame (with a lower level of anti-alias) to look good. I thought, wow, if I can reneder them separately and composite them I would be in business. Alas, I have not found it to be easy to separate the two since the ecosystem and terrain are together in Vue. This is why I started looking at g-buffer and muti-pass. The RPF method looks like it might work, except, I am using X-stream with XSI to add an animated coyote to the scene. Now, it appears that XSI does not recognize the Vue objects to its render passes. So I am stuck. I am begining to wonder if the concept of xstream is viable for serious cgi.

Maybe I am making this too complex, but so far I have not found a solution. This seems like a complex subject that needs to have some light shed on it.

A tutorial on this topic or a reality check would be great!

Mike

[vovka]

Most "flickering" happen in ecosystem, reason - millions of leaves moving, changing reflection and lighting.
To reduce flickering in animation, if it possible in your idea, turn off wind, no breeze animation on plants.
Problem with light optimization and how it cutoff values when it's calculating reflection light, plus no collision detection leaves, so they cross each other. Increasing atialising or sharpness, just work with light optimization, not with source of flickering.

[MTM]

Normally, I would agree that flickering would be mainly a problem of the ecosystem. In this case, however, there is no wind, the bushes have no leaves (tumble weeds). The flickering is entirely coming from the terrrain (.tif material). The problem is that the anti-alias I need for the ground is also applied to the ecosystem (that does not need it) and thus takes forever. To make matters more difficult, xstream and xsi don't make it easy (or is it even possible) to render these separate passes (ecosystem and terrain). At least, I don't see how to do it.

I believe the solution is compositing, after performing separate render passes on terain vs everything else.

Mike

[jcbrown]

Well, from what I have learned over this time, all I can say is that both are totally different. Of course, you definitely need to save the G buffer and I get that and so is the case when you need to do the multi pass. But if you think you can achieve both at the same time then I must say that you are told wrong by someone. Handling G buffer will give you the insurance of getting information that you want, mind you!

[Erwin0265]

So where is this table that lists what each channel/layer of the multi pass and g buffer does [as mentioned in the book - page 287]?
I can't find it anywhere...................
And I would also like to add that a complete tutorial on this feature would be great - no-one has created one, it appears; always skimming the topic, but never explaining what ech layer/channel can be used for [even the book has a mere page on this rather indepth topic].

[vovka]

I have few tutorials about multipass and g-buffer on site. And prepearing new tutorial where i am using multipass and layer to create book cover illustration. It should be out soon.

[Erwin0265]

Vladamir,
Thanks for the speedy reply.
I have watched one of your tutes on the multipass feature, but nothing that covers [comprehensively] what each layer/channel can be used for in Photoshop.
The tute I refer to is, "33. Introduction to Vue 9. Multipass Render".
You do go through what type of masks and channels can be saved; but what can all of the layers/channels be used for?
Masks in the channel tab are obvious [to me - but for newer users, may not be; it is, after all, anIntroduction], but what can you use all of the layers in the layer tab be used for?
For example, I may have layers for different terrains; all of the thumbnails are black; what are they for?
What other tutorial covers the multipass feature?
Thanks for your time.
Erwin

[Erwin0265]

OK,
It's been a few weeks; surely someone knows something more about this issue??!
I can see that my post has been added to similar questions posted way back in 2008; yet there still are no real, useful answers.
Vladamir; you mentioned:-
"I have few tutorials about multipass and g-buffer on site. And prepearing new tutorial where i am using multipass and layer to create book cover illustration. It should be out soon."
Great!
But you have not let me [or anyone else] know where they are. If I knew, I wouldn't be asking...........

Please understand; if this post appears to have a rude tone to it; this is definitely not my intention - you provide a wonderful service to the Vue community.
My tone is one of frustration.
I have probably got over a $1000 worth of tutorials from numerous sources; Not one gives me a conprehensive overview of the Multi-pass feature.
Many mention it's existence and some things you can do with it; but nothing comprehensive and useable.
I believe it is one of those features where, if you knew Photoshop, or Nuke inside out, it would all be obvious.
But many of us who post on the forum/s are hobbyists, not professionals.
As hobbyists, we may have equal talent to many of the professionals [after all, talent cannot be taught]; but our work can appear less polished because we lack the knowledge; knowledge that [I think] many professionals take for granted and simply don't realise we don't have.
The book, "Vue 7, From the Ground Up" is a good example [from my point of view anyway]; there is a single page on what the multi pass and g buffer does; that's it!
As I mentioned in my first posting [June 20, 2011], there is mention of a table that covers what each channel/layer does on the book's website [this is what helps those of us who are not professionals and is, frankly, essential].
Unfortunately, I cannot find it anywhere on the site; was it something that was planned to be done, but wasn't; was it removed because no-one used it; or am I just blind and it's right there staring me in the face [if so - PLEASE lmk the link]??

Anyway, I hope that I have gotten my point across; I am still stuck and I have left Vue alone and am back to learning more about Photoshop [I tend to hop from one application to another; at least until I know enough to be able to use them all in a usable workflow].

I again await to hear the wisdom from all that are wise...................
And please remember; If I have sounded rude/obnoxious/a pain in the ___/etc; it was not my intention.
I just want to learn...................
Thank you

[vovka]

It's may help if you tell me what you looking directly. You can contact by skype and we can share screen, this way will be way easer to explane some questions. Search for geekatplay at skype (if you using it) or send me direct email, so we can connect other way. (my writing english not so good )

[Erwin0265]

And here we are, months down the track - after making direct contact [as requested] - but no response at all.
Why oh why offer help if I contact you directly with specific issues [which I did, in full detail] when you're not going to bother to respond?
What you do for the Vue community is great; but this just plain simply annoys me [I'm trying to be polite here.............].
Has ANYONE [who will actually tell me] worked this all out yet?
I suppose it's time to buy some other books; support for this one appears to have left us.............

[vovka]

I may missed your request. skype : geekatplay

[Erwin0265]

I pm you a rather long message [11.7.11] entailing everything that I wanted to know.
I don't have Skype as we are on opposite sides of the Earth [so your time would be no good for me, and vice versa].
You suggested pm ".....or send me direct email, so we can connect other way. (my writing english not so good )"; so that is what I did.
I really don't care if your written English isn't so good; your spoken English is also hard to understand [no offense meant] - I have a lot of difficulty understanding your tutorials; both Amy's are easy - but English is not your native tongue [spoken or written]; that's no big deal.
One problem I have is remembering spoken conversations; written is way better for me.
So please; just write back; I'm sure that I will be able to work it out from there.
Lastly, the book mentioned a table that lists what each channel/layer of the multi pass and g buffer does [page 287]; where is it? Or please, just give be a link.......
Some of my original entries in this post [20.6.11 & 21.6.11 & 9.7.11] go through what I want to learn [I hope you still have my pm to you as I appear to not to have kept a copy].
Hope you can give me all that I need regarding this potentially useful feature...............