Friday, July 29, 2011

HR Project Lighting Settings

Hi all,

Here are the settings and accompanying screenshots for lighting/rendering on the HR project. You may have to click on the images to make them large enough to read.

To begin, open up your Render Global Settings window. Make sure it is set to render with Mental Ray and not Maya Software or something else.

Settings for Common tab:

  • Image format should be changed to OpenEXR (the exr format is ideal as it allows for multiple passes to be contained in a single file whereas these same passes would have to be split up into separate files using almost any other file format. The exr format also has good support for floating point bit depths, which is also lacking in many other formats).
  • Frame/Animation ext should be changed to "name.#.ext" (most compositing programs prefer this formatting for image sequences)
  • Be sure to change the Frame Range and Renderable Camera to the proper settings for your shot
  • Change the height and width of your shot to 720 pixels wide and 388 pixels high

Settings for Passes tab:
  • Under render passes press the button with an image of a sparkling clapper that will be in the top-right most corner of the window. This will bring up a dialog with different types of passes to choose from. Create passes for 2D Motion Vector and Camera Depth and then close the dialog.
  • After doing this you must explicitly add these passes to each layer you wish to have it rendered out for (thus all passes don't need to be put out for all Render Layers). When highlighting a pass, a button with a image of a clapper and a green checkmark should no longer be grayed out; pressing this button will associate the highlighted pass with the currently selected render layer. The Camera Depth pass should be added to every single layer pretty much without fail. The 2D Motion Vector pass only needs to be added to render layers that have moving objects in them (keep in mind that if your camera is moving then, for all intents and purposes, all your objects in all your render layers are moving)

Settings for Features tab:
  • Render Mode should be set to Normal
  • Primary Renderer should be set to Scanline
  • The only secondary Effect that should be toggled on should be Raytracing. If you are not using Raytrace shadows you should also turn this off. If you are unsure of whether you are using Raytrace shadows or not then simply leave raytracing on.
  • Shadows should be turned on
  • Motion blur should be turned off (the 2D Motion Vector pass will allow us to compute this in post)
  • All other settings on the Features tab can be left at their defaults.

Settings for Quality tab:
  • Under Anti-Aliasing quality:
    • Set sampling mode to Custom Sampling
    • For foreground render layers set Min Samples to 0. For background render layers set Min Samples to 1.
    • For foreground render layers set Max Samples to 2. For background render layers set Max Samples to 4.
    • For Multi-Pixel filtering set the Filter Type to Gauss and Filter Fize to 3.0 x 3.0
    • Under Anti-Aliasing quality, all other settings can stay at their defaults
  • Under Raytracing
    • Raytracing should automatically be turned on when you toggled it under the Features tab. If for some reason it is not on then do so now.
    • Set Reflections to 3
    • Set Refractions to 3
    • Set Max Trace Depth to 10
    • Set Shadows to 2
    • Set Reflection Blur Limit to 1
    • Set Refraction Blur Limit to 1
  • Under Framebuffer
    • Set the data Type to "RGBA (Half) 4x16 Bit"

Under the Indirect Lighting tab:
  • Be sure to click "Create" on "Image Based Lighting" if Rob has photographed an HDR image for the set you are lighting. When you do so an Environment light will appear in your scene's outliner. Be sure to set all your option appropriately within the environment light (such as which HDR image to use and so forth).
  • Make sure all other indirect lighting options are turned off. Most of these features add an excessive amount of work to mental ray which slows down render times considerably. Also, some (such as Final Gather) can sometimes cause flickering renders, which means you may have to re-render your entire shot or at least individual frames. Joe Creswell recommends using Final Gather in his previous post as it does improve the quality of the final renders (as do most indirect lighting features). However, Hazel and I have found the high render times and flickering frames to not be worth the time and effort. I suggest avoiding Mental Ray's indirect lighting features (other than image based lighting) whenever possible. Similar features can be faster to render in some other renderers, but as a general rule indirect lighting features are slow and/or hard to work with in most renderers and should be avoided unless necessary (or you have a large, fast render farm at your disposal or you are only rendering a single still image).

Under the Options tab:
  • Leave these settings alone. Whatever defaults Maya has in here should be just fine.
Be sure to smooth all geometry before rendering. By this I mean select all geometry to be rendered and press the 3 button to use Maya's smooth preview. Mental Ray will understand that this means it should subdivide at render time (and not before). If you do a true subdivision (smoothing) to your geometry before rendering this will cause more geometry to have to be sent to Mental Ray, which will in turn slow down your renders considerably.

Pretty much all other settings will be dependent on your setup of lights and geometry in your particular scene. I recommend using raytrace shadows on area lights with 16-32 Shadow Rays and a Ray Depth of 3. If you want softer shadows simply scale the size of your area lights (keep in mind that this will increase their area of illumination thus lighting everything more brightly so you may need to turn down the intensity of your lights after scaling up their size). Area lights mimic more accurately the way real light sources act and thus give better looking lighting with less effort. Raytrace shadows are much easier to manage than depth map shadows and also look better and more accurate with less effort. Since Mental Ray is a raytracer it renders raytrace shadows at decently fast speeds.

I do not recommend using light decay unless you find that you need it to make your lights illuminate correctly. With light decay off your lights will be less physically accurate, but will be more predictable to work with since they will infinitely illuminate at the same intensity.

That is all I have for now. As I think up more tips and tricks I will edit this post and add more. Good luck!

1 comment:

Hazel Law said...

As far as I know you should have Final gathering turned on or else the environment light won't work.