I'd been following ILM's Open-Source, OpenEXR format for some time, (www.openexr.com/). It's a format that supports up to 32-bit, floating point images, with additional channel buffers, and modern, lossless compression technologies. It's solid-color areas are clean and continuous, and with its RLE, ZIP, ZIPS, and PIZ supported lossless compression algorithms, the files are small and easily portable. After exploring it in the later days of production on Kaze, Ghost Warrior, it became my file-format of choice.

Pieces
This summer, Kelly "Kat" Myers, the VFX Consultant on Battlestar Galactica introduced me to an EXR saver plug-in he was testing for the show. And while I don't want to sound like an "infomercial," I really like the way exrTrader worked into both Galactica's pipeline and my own, solving a lot of outstanding problems other solutions still haven't addressed.

ExrTrader (exrtrader.com ) solves the problem I've had for years when working with Buffer-Savers, in that it polls LW to see where you have your Save RGB Output Path set, and writes its image there, without needing to be told in its Image Filter interface. (There were a couple times on Kaze where I forgot to change an older Buffer Saver Plug-in's output directory and ended-up overwriting perfectly good renders.) ExrTrader integrates a "Dummy" Image saver into your Render Globals > Output > Save RGB > Type options so that LightWave and network rendering apps know where to expect the .exr files it saves, but LW doesn't actually need to write an image file with its standard, non-Layered image savers.

(EXR Trader)

The Layering ability of exrTrader lets you choose to include in your rendered image, if you wish, additional buffers for: Raw Color, Reflection Color, Diffuse Color, Specular Color, "Special" Buffers, Luminosity, Diffuse, Specularity, Reflectivity, Transparency, Shading, Shadow, Geometry, Depth, Diffuse Shading, Specular Shading and Motion Buffers. All this can be written into a single file, or be written into separate files in subdirectories it makes, drawn from the Base name you can modify for each Channel.

And something else I found very handy with exrTrader is its ability to save both network/global Presets and individual user presets. So, whenever I have to export Buffer-set "A" for my Radiosity or Translight pass, I just select it from the drop-down box, just as I do for Buffer-set "B" for key-light specific Shadow, Specular highlight and Diffuse information.

I'll be showing you some techniques on how to use some of these Buffers in the following article, but to get you started, here are examples of most of the buffers, what they do and how they can be used: