February 22, 2012

Light Escaping the Computer

By Andrew at 9:20 AM

What exactly is a “render wrangler”?  I am looking forward to tackling that question, but first I think that I need to define “rendering”.  In another post, I will build off of this definition and further explore what my job looks like.  For now, I will try to adequately describe a process that I am a part of and why it is needed.  In college, I was fortunate enough to work on an independent study related to rendering, and as a result, I created a presentation which contained a description of rendering.  So, building off of that, here goes!

In animation and the majority of digital media production, including filmmaking, rendering is the process of converting multiple pieces of video, photos, drawings, and so forth, into a single, polished image.  Once the animator/film editor/artist finishes arranging the pieces on his digital artboard, he will then wish to take a photo of the final product so that the edges can be trimmed up nicely and duplicated, in order to share his finished piece of art with the rest of the world.  What remains is the “flattened” image of all the pieces that went into creating the final product, yet it only retains the visible information related to the interaction of the pieces with each other.  This allows the storage of such images to be much smaller than would be required to store multiple copies of all the original pieces.  This is how rendering video works for the most part, but animation is a bit more complex.  Computer animation is made up of objects that have never physically existed in the “real world,” yet we wish to “take pictures” of these virtual objects.  Rendering for animation is a process of painting digital objects, bouncing light particles (in some software, literally called “photons”) off of their surfaces, and photographing the resulting photons using a virtual camera.  As some of you may know, we are able to easily create a conceptual line inside of a computer by defining a start point and an end point.  The difficult part, however, is to convert that line to a representation which can be displayed on a computer screen.  If you take a look at your computer screen, you will see that it is made up of many tiny dots (pixels).  These pixels cannot, of their own accord, display the representation of a line merely defined by two end points and filling in the line between them.  But in rendering, as photons bounce off of objects and lines, computers can interpret their proximity to a virtual camera lense and assign a color value to an individual pixel at a location on the screen, based off of how much influence the photons have at that specific location.  Think of it as a window screen or a grid, and when the computer forces the finished output through the screen (double-meaning intended), small chunks of visual information are passed through to form a mosaic of sorts.  The screen can only handle one piece of color information per pixels, but with current technology that is enough to create what would appear to be a recreation of a virtual object in the physical world.

As you may have guessed, for a single image to be created, millions of individual pixels must be properly arranged on a screen.  And by extension, video is made up of thousands of these still images for even a few minutes of video.  While computers are great mathematicians and can handle such tasks with ease, the time required for a computer to handle such an image can be quite long.  The more complex or realistic an image becomes, the more time it will take for a computer to finish the image.  And when there are hundreds of thousands of images to work on, well, the time really adds up.  It is not unusual for computers to take hours or even days on end worth of computation time to create an individual image.

Whew!  An incredibly complex process, I know, but in reality my description barely scratches the surface.  There are actually multiple rendering phases involved in the movie-making process, but it can ultimately be pared down to the representation of virtual objects through a series of pixels on a screen.

I hope my quick explanation of rendering makes sense.  It is an incredibly complex process, and I do not claim to know more than the most basic of what is actually behind the equations and mathematics of rendering.  In an upcoming post, I will talk more specifically about my role in the rendering process, but I hope that this post will help lay some groundwork.  Thanks for reading, and as always, please feel free to contact me if you are interested in hearing more about this topic!

Comments »

  1. Valerie Van Ee — February 23, 2012 @ 8:32 AM

    Hey, Hope you are enjoying Dream Works. I really like reading your blog. It gives me a slight hope for the future. lol. As you may know I took over render farm on campus. I enjoyed reading how you define rendering. I’ve got many blanks stares when I tell people I work as a render wrangler or work on a render farm. I think you did a good job explaining what rendering it.

  2. Andrew — February 27, 2012 @ 4:49 AM

    Thanks Valerie! I am enjoying DreamWorks, and I am learning many new skills at the same time. Keep up the hard work, and be sure to feature your render farm work on your resume. Wrangling is a great entry level position, and previous wrangling experience may be just the thing to get you noticed in the “industry.”

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