InFusing CSI
By: Eddie Robison

When CSI: Miami VFX Supervisor Larry Detwiler phoned to ask if I was interested in doing their "money shot" for episode 618 of the hit T.V. drama, I jumped at the chance without ever considering the potential difficulty. After 17 years of doing Television and Film visual effects I had taken a Senior Artist position at Inhance Digital. Inhances’ mainstay has been producing corporate animation and post that is a little known, but highly profitable sector of the effects industry. They have recently been branching out into the entertainment side of the business after moving to the heart of Hollywood from San Jose, CA just over a year and a half ago. Such a high profile shot on one of T.V.'s number one shows could not be passed up, even with the tight turn around.

The shot would consist of an HD plate with two cars driving toward a locked off camera in broad daylight with the cars almost filling the frame. The less fortunate car on the right would drive into a sinkhole triggered by the cars weight and violently smash down through the roadway. After the writers’ strike, shows like CSI have been scrambling to catch up with three or four episodes in production at a time so, in this case, plans to shoot additional practical elements were foregone at the last minute. This left me a single plate with both cars in it to work with. Here begins my part in bringing this shot home.

(Click Image For A Larger View)

The Plate was shot with both cars moving slowly, the one on the left driving past camera left and an unlucky Pontiac GTO stopping right where the CG sinkhole was to open up. Since there was no clean plate filmed, I first had to combine the first and last frame to make a clean frame, painting out the GTO entirely. A road sign on the right was also painted out in Photoshop and I removed the grain there as well. This "clean frame" and the moving plate were then brought into eyeon's Fusion. Fusion is my compositing package of choice and the only package suitable for this job due to many factors that I will discuss here. I stabilized the plate to remove the subtle gate weave and merged my clean frame over using Fusion's tracker with an animated mask to completely remove the doomed GTO. The car on the left, a silver BMW, had an obvious reflection of the red GTO on its door that had to go as well. To accomplish this I simply tracked a soft edged mask around the reflection and used this to desaturate the reds and a gaussian blur to soften the detail. I also added film grain back to both that portion using the same mask, and to the portion of the clean frame that is now covering the GTO. I then doubled the speed of the plate to bring the BMW on the left up to an exciting pace. Now I had a prefect plate I could work with and I saved my new version as a half resolution jpeg frame sequence to my local drive for easier use in my 3D package.

(Click Image For A Larger View)

On this kind of time frame there's no way to do any real modeling so I turned to the source so many artists have before me. Turbo Squid has a multitude of models including the Pontiac GTO that I needed, so that was a no brainer. I did do extensive clean up and retexturing of the model as well as rigging up a pretty convincing 3D driver to flail around behind the wheel as it went crashing into the "Pit" (as I came to refer to it).

Using lens information and camera height recorded on set, I easily matched my 3D camera to the practical one used in filming and brought my 3D GTO into the scene to start animatics. Having the plate in the background with the BMW in frame helped me fine tune the perspective and gave me good size and speed reference as well. Going back and forth with a few quicktimes Larry and I settled on our timing for the shot and I got down to work.

(Click Image For A Larger View)

For the “pit” I first modeled a piece of the roadway in Newteks Lightwave 9.3 and I busted up a rough hole in it by hand, extruding each piece as I went. This object was textured using a few reference frames of the sinkhole (provided to me by Larry) they created on set with a practical GTO nose down in it. I used Lightwave’s dynamics system to simulate the road giving way, using collision and gravity. I added to this both hand animated chunks of rubble as well as other dynamic simulations for the impact of the car. All of this proved to be very much a trial and error process since I've never seen a sinkhole actually collapse. After some tweaking I came up with something that was convincing and rendered out separate passes with the GTO as a matte object to provide shadow on the falling debris.

(Click Image For A Larger View)

The car itself was initially rendered in four separate passes to be combined in Fusion later, but I soon found that using Area lights and Global Illumination gave me almost exactly what I needed in one pass. So, I rendered it out two ways, with and without reflections. The reflections were accomplished using my clean frame of the plate wrapped around a dome since there were no HDRI images (or otherwise) shot on set. Using another 3D car, I match moved it next to my GTO and made it unseen by the camera but visible by rays so that I had some reflection play on the side of the hero car. I did have trouble matching my windshield reflections to the BMW's glass so I tracked a separate 3D windshield onto the BMW and rendered new reflections for it, which I would later add in comp so that they matched perfectly. Lastly, I rendered a shadow pass for my GTO and then brought all of my elements together in Fusion to begin my comp.

(Click Image For A Larger View)

I started by using the cars shadow pass as a mask to color correct through to the plate, matching the real world shadows of the BMW. I accomplished this by going through each of the RGB channels, one by one, using the RGB levels of Fusions color corrector to match each channel. This gives you shadows that have color in them, not just a dark patch on the ground. Using this method for all of my color correction also means that no matter the differences between my monitor and the client's (or ultimately the home viewer's) the blacks will always match and won't just be based on what looks correct on my monitor here at Inhance. Because I originally had a plate with both real cars in it, I could use this color correction method to match my CG car to the real one as well. Each 3D render was layered over my clean background plate in succession and all motion was approved by CSI to go to final.

(Click Image For A Larger View)

Having spent more time than I wanted to with the dynamics in Lightwave, coupled with the fact that the second unit element shoot ended up not happening, I was left with one option for the remaining elements I needed to complete the shot and deliver it on time. I had a convincing street that caved in and a photo realistic CG GTO to crash into it, but I need additional small power debris and a lot of dust and smoke. For this, I dipped into my library of stock elements, all at very different resolutions, which is one of the many areas where Fusion really sets itself apart from it's competitors. Fusions resolution independency is invaluable for doing this kind of thing. I was able to use a variety of methods to key my various elements and set them up onto 3D image planes using Fusions native 3D compositor. This method makes it really simple to layer my dust, smoke and debris elements in front of and behind my cg car layer. The ability to use true 3D in my compositor saves me time and effort and adds a whole new level of control to my comps not found in other packages. I am also able to work from my half resolution files for speed and switch out proxy plates for the full resolution at render time. All of my custom masks then automatically scale up to fit exactly the way that I cut them at half resolution. Again, this underscores Fusions power as a versatile production tool. I finished the shot off by mapping my comp back onto a 3D piece of geometry match moved to the BMW and adding the result back onto the door in comp. At speed, you can't really see it but it’s one of those little things that are felt rather than seen. Regardless, I know it's there and it's correct. It's the little things........

In short, mastering the tools made available by eyeon has allowed me to take on, with confidence, the most daunting of tasks and helps me remain flexible as I work in the face of unexpected changes. I'd like to thank the guys at eyeon for making such a superior product and CSI: Miami for giving Inhance Digital a chance at creating some great shots for their hit series. Thanks for reading!

Visit eyeon at www.eyeonline.com
Inhance Digital at www.inhancevfx.com
or myself at www.eddierobison.com