Issue link: https://digital.copcomm.com/i/17668
3D Stereo Compositing of the work you can do concentrating on just one view before you really need to see how the images work in the stereoscopic world. From the beginning, our layout department establishes a working stereoscopic value for Suspect worked on this stereo project for fashion design house Armani Exchange. It features both live action and animation. each shot. But whether the shot is in stereo or 2D, all the environment and creature work takes the same amount of attention to detail to get it to work with in the plate.” SAROKIN: “Yes, for the project we most recently worked on — Honda’s Eclipse — we used Flame, Nuke and Ocula to do the compositing, with Maya and Mental Ray to create the CG.We use Flame as our pri- mary compositing tool for most jobs, but because Nuke has such an excellent stereo- scopic toolset in conjunction with Ocula,we decided to use it more than usual.The most recent Flame upgrade had a number of stereo features, which we certainly put to the test with great success, and along with Nuke we were able to tackle any of the problems we came across.” LAMBERT: “Nuke already has robust 3D capabilities, so it handles two cameras very well and we did not have to make any signif- icant pipeline modifications to accommo- date 3D work.” POST: Did you have any problems with alignment from the stereo rig or color/lens dif- ferences from the two cameras? COX: “Misalignment and color shifts are a fact of life for stereo shoots.They need to be efficiently dealt with for every 3D shoot, if you want to provide perfect 3D that gives a strong 3D image that isn’t tiring to watch. Mistika scores well here — point and click line-ups between left and right images, with the alterations being applied in realtime with no need for rendering. My method for working in 3D is that immediately after the conform, I run through the edit correcting the misalignments and color shifts and apply a ‘first-level’ depth grade to make the edit comfortable to watch.Thereafter, I just work 32 Post • October 2010 as normal, applying visual effects and color grades as required.” CREAN: “Yes.This issue is inescapable in the realm of stereoscopic live-action shoot- ing and compositing — even minuscule dif- ferences in vertical positioning can create alignment problems. Additionally, you may be surprised how different the light on an ob- ject or actor can look when viewed from just 64mm to the left or right. Most native stereo shooting will happen on a beam splitter as well, so right off the bat you are taking a lu- minance, saturation and sharpness hit in one eye. Finally, with a ‘toe-in’ lens configuration, there is bound to be some keystoning at the edges of your image, which needs to be cor- rected. Before you even get into composit- ing, all these issues should be dealt with as they will certainly haunt you throughout the post process — not to mention causing eye- strain and fatigue for viewers.” ALEXANDER: “We always knew there would be differences in the cameras that needed to be adjusted before we could begin work on shots.The alignment issues fall to our layout department.We have devel- oped some very specialized tools that make this adjustment seem nearly invisible to the rest of the disciplines contributing to a given shot.Although there are certainly times when hand-tweaking is necessary, the plan is to make this step as procedural as possible.The same can be said for the color adjustments. It’s really no different than color timing shots in a sequence.Although you can pickup some highlight differences randomly as the camera moves, you’re going through a set configura- tion of lenses, mirrors or beam splitters so within the shot it should be a pretty constant difference that needs to be adjusted.We are not quite there yet but our goal is to make this be a completely procedural process that will resolve the issue without much, if any, in- dividual tweaking per shot.” SAROKIN: “Definitely. Because we shot the Honda commercial using a beam splitter rig, there were significant color discrepancies between the plates. Highlights, reflective sur- faces and overall color balance were very different and we went to great lengths to correct the disparity between them. Align- ment wasn’t such an issue as we shot paral- lel rather than converged. Minor adjust- ments were necessary but it wasn’t nearly as much of an issue as the color differences.” LAMBERT: “When shooting with a 3D camera rig, there can be a polarization issue. The rig’s mirror system produces slightly dif- ferent colors, reflections and specular high- lights in each eye,so we worked closely with The Foundry to update the color matcher node that is now included in their latest re- www.postmagazine.com lease of Ocula. Having this solution in place will be a big help from now on, and the lat- est 3D camera rig also includes an updated mirror system designed reduce some of the issues mentioned above.” POST: How much additional roto and paint work did you have to do (if you shot stereo) specifically to fix stereo problems? COX: “If you are rotoscoping to cut out objects, then although there are some tricks using disparity maps, you are most likely going to be rotoscoping twice. It’s also worth bearing in mind that any horizontal difference in your matte edges will appear as different depth planes in a 3D composite. In terms of fixes specifically for stereoscopic shoots, a common one is dealing with light reflections that are different between the left and right eye. Imagine a shiny tabletop that has a sheen across it from a light.The chances are, its got a different sheen in the left and right images because of the different angles. If this difference is too strong, it makes the viewer uncomfortable because it makes them feel like one eye isn’t working properly — like when you have water in one eye or something obscuring one of the lenses of your sunglasses.The fix is often to roto out the sheen from one image and warp/comp it into the other image.” CREAN: “The nature of stereo composit- ing is such that roto and paint work must be very precise: ideally every brush stroke or garbage mask will be duplicated accordingly in the other eye. So while there wasn’t any specific situation where a stereo problem was ‘fixed’ with roto, there was plenty of it to One of Digital Domain’s work areas. cut out the mattes of all the talent, with their windblown hair and clothing,as well as plenty of beauty retouching.We did cut additional mattes in order to ‘dimensionalize’ or con- vert some 2D scenes into 3D stereoscopic.” ALEXANDER: “In our experience, we’ve found it is pretty close to being twice the work.We have amazing in-house roto and paint applications and amazing roto and paint artists. I have to constantly remind my- continued on page 55