Closed Thread
Page 1 of 3 1 2 3 LastLast
Results 1 to 10 of 24

Thread: Definitive Guide to VRay and Render Passes

  1. #1
    Junior Member
    Join Date
    Jun 2006
    Location
    Arizona
    Posts
    6

    Name
    Shawn Lochman
    Forum Username
    fire3d

    United_States

    Default Definitive Guide to VRay and Render Passes

    After using Brazil R/S for some time I decided to get with CGIs architectural adopted format VRay. Honestly, I feel comfortable with the renderer at this point. What I am looking for is more information on rendering passes with VRay. I didn't really have a lot of experience in architectural visualization or composting so I purchased Tim Jones's DVD Environment Creation for Production. Working through his online tutorial http://www.seraph3d.com/CompositingTutorialA02.htm he gives examples of rendering passes with the scanline renderer.

    My issues is that I can't get my passes to look correct with VRay. After spending two frustrating weeks with this I am at my wits end. So my question is is there a more definitive guide on rendering passes with VRay?

    I did find a nice script by Marc Lorenz to quickly render ambient occlusion in VRay.

    http://plugins.angstraum.at/vrayao/index.htm

  2. #2
    Senior Member
    Join Date
    Nov 2004
    Location
    Montreal
    Posts
    279

    Name
    David Rees
    Forum Username
    DavidR

    Canada

    Default Re: Definitive Guide to VRay and Render Passes

    watching this thread

  3. #3
    Senior Member bigroo's Avatar
    Join Date
    Jun 2005
    Location
    Cobham
    Age
    48
    Posts
    308

    Name
    Michael Daburn
    Forum Username
    bigroo

    England

    Default Re: Definitive Guide to VRay and Render Passes

    I'd say the best (& free) definitive guide to Vray is at http://www.spot3d.com/vray/help/150R1/ and it sure helped me when I first started looking into it.
    Last edited by bigroo; August 31st, 2006 at 06:15 AM.
    All things in nature are dark except where exposed by the light. Leonardo da Vinci

  4. #4
    Moderator Christopher Nichols's Avatar
    Join Date
    Apr 2002
    Location
    Lalaland
    Posts
    1,163

    Name
    Christopher Nichols
    Forum Username
    Christopher Nichols



    Default Re: Definitive Guide to VRay and Render Passes

    Quote Originally Posted by fire3d
    After using Brazil R/S for some time I decided to get with CGIs architectural adopted format VRay. Honestly, I feel comfortable with the renderer at this point. What I am looking for is more information on rendering passes with VRay. I didn't really have a lot of experience in architectural visualization or composting so I purchased Tim Jones's DVD Environment Creation for Production. Working through his online tutorial http://www.seraph3d.com/CompositingTutorialA02.htm he gives examples of rendering passes with the scanline renderer.

    My issues is that I can't get my passes to look correct with VRay. After spending two frustrating weeks with this I am at my wits end. So my question is is there a more definitive guide on rendering passes with VRay?

    I did find a nice script by Marc Lorenz to quickly render ambient occlusion in VRay.

    http://plugins.angstraum.at/vrayao/index.htm
    You will find that most people that use Vray will find no use for AO unles they want an extra bit of dirt. Which is why the AO shader in Vray is called a VrayDirt. As far as making passes and compositing back together, I did this a while back

    http://www.chaosgroup.com/forum/phpB...ic.php?t=13818

    Vray can split out all the relavent layer info and can be reconstructed in comp.

  5. #5
    Senior Member martin walker's Avatar
    Join Date
    Jan 2005
    Location
    Yorkshire
    Age
    42
    Posts
    344

    Name
    Martin Walker
    Forum Username
    martin walker

    United Kingdom

    Default Re: Definitive Guide to VRay and Render Passes

    [QUOTE=Christopher Nichols]You will find that most people that use Vray will find no use for AO unles they want an extra bit of dirt.QUOTE]


    Christopher, Im intrigued by that comment. I use AO quite considerably, especially coupled with a direct light I get excellent rendering times for a decent result.

    Ive found the v-ray lights extremely slow and grainy, especially in interiors

    Id be interested to hear your reasoning behind not using AO and opting for V-Ray lights.

    btw....your DVDs where a great help when i first started using V-Ray !

  6. #6
    Moderator Christopher Nichols's Avatar
    Join Date
    Apr 2002
    Location
    Lalaland
    Posts
    1,163

    Name
    Christopher Nichols
    Forum Username
    Christopher Nichols



    Default Re: Definitive Guide to VRay and Render Passes

    [quote=martin walker]
    Quote Originally Posted by Christopher Nichols
    You will find that most people that use Vray will find no use for AO unles they want an extra bit of dirt.QUOTE]


    Christopher, Im intrigued by that comment. I use AO quite considerably, especially coupled with a direct light I get excellent rendering times for a decent result.

    Ive found the v-ray lights extremely slow and grainy, especially in interiors

    Id be interested to hear your reasoning behind not using AO and opting for V-Ray lights.

    btw....your DVDs where a great help when i first started using V-Ray !
    Just keep in mind that the whole AO pipeline was developed for people that don't have the luxury of full GI, such as renderman users. They needed a way of creating the "look" of ambient light without having to calculate it. So elaborate AO pipelines were developed, starting with Pearl Harbor. With Vray GI is practically free, as light, especially diffuse light, bounces around very fast and nicely. I always use these two images as examples of that:




    The math is the same in either case, just multiply it by the diffuse color... it is just that you get the proper light bouncing around. Like I said, sometimes people use the AO pass like a dirt pass to darken corner. Never use an AO pass on an interior unless it is for dirt. The only way to get ambient light in an interior is to have it bounce around.

  7. #7
    Senior Member martin walker's Avatar
    Join Date
    Jan 2005
    Location
    Yorkshire
    Age
    42
    Posts
    344

    Name
    Martin Walker
    Forum Username
    martin walker

    United Kingdom

    Default Re: Definitive Guide to VRay and Render Passes

    Thanks Christopher

    I think im getting my terminlogy confused, isnt AO the process of using the ambient /environment colour as a "light" which is bounced around by the GI ?

    or am I mis-understanding the process ?

  8. #8
    Moderator AJLynn's Avatar
    Join Date
    Aug 2004
    Location
    Boston / Cambridge
    Age
    35
    Posts
    6,446

    Name
    Andrew Lynn
    Forum Username
    AJLynn

    United States

    Default Re: Definitive Guide to VRay and Render Passes

    The AO Chris is talking about is a pass for faking GI. Basically, when rendering, from each sample point draw a hemisphere over it and randomly shoot some HSphere rays. If they hit something, they return dark. If they don't hit something, e.g. they escape to the environment or hit the max distance, they return bright. Average the darks and brights to get the shading.

    So it's not based on actually bouncing any light, it just darkens a surface according to how much of its environment is "occluded" by other objects within a certain distance. It's really good at darkening the inside of your corners, if you have a radiosity render and you need to add a bit of "something", some kinds of dirt, some NPR techniques, but for our purposes when doing Vray renders it's easier, faster and looks better to do real GI instead.

  9. #9
    Moderator Christopher Nichols's Avatar
    Join Date
    Apr 2002
    Location
    Lalaland
    Posts
    1,163

    Name
    Christopher Nichols
    Forum Username
    Christopher Nichols



    Default Re: Definitive Guide to VRay and Render Passes

    Exactly as AJ tells you, but most people that use AO want you to think that it is in fact the light from the environment. Compared to true GI, it is far from it. I laugh when I read articles that claim they do GI via Ambient Occlusion. That is like saying I drive my car via ridding my bicycle. In order to be consider global illumination, the scene need to be illuminated by everything in the environment, including the scene itself. AO does not collect color, and does not bounce. Again, the GI method that is done is Vray is something that many places wish they had. That is why many mid to high end VFX places are switching to Max and Vray (or other GI rendering) just to have access to fast GI. The only thing that is stopping really big VFX shops is that their pipelines are so tied to their current system. It will take years for them to switch.... plus renderman has so much legacy, it will take years and years for it to adapt as well. Keep in mind that Renderman is a rendering engine that just got multi-threading this year.

  10. #10
    Moderator Christopher Nichols's Avatar
    Join Date
    Apr 2002
    Location
    Lalaland
    Posts
    1,163

    Name
    Christopher Nichols
    Forum Username
    Christopher Nichols



    Default Re: Definitive Guide to VRay and Render Passes

    One more thing.. Dirt is based on the AO thing. In the new Vray, there is a dirt shader. It is pretty cool because you can control distance, angle, falloff, even XYZ. Dirt is great.... Just don't confuse it for an actual lighting pass.

Closed Thread
Page 1 of 3 1 2 3 LastLast

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

     

Similar Threads

  1. render strips using vray frame buffer
    By seamus in forum V-Ray
    Replies: 5
    Last Post: August 6th, 2009, 05:35 PM
  2. Render Elements Vray Demo 1.5 RC2
    By CADuzer in forum V-Ray
    Replies: 4
    Last Post: August 29th, 2006, 06:26 AM
  3. render texture with vray
    By d7man2000 in forum V-Ray
    Replies: 2
    Last Post: January 21st, 2006, 05:42 AM
  4. vray render
    By Boizell in forum V-Ray
    Replies: 5
    Last Post: November 18th, 2005, 03:37 PM
  5. Vray free and Viz 2006 taking hours to render..
    By alfienoakes in forum V-Ray
    Replies: 5
    Last Post: October 27th, 2005, 08:44 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts