Matthew Merkovich Says to Stop With the Crazy Tracking Markers

You probably have seen some behind the scenes reveals where there are crew and talent alike huddled around huge green screens that will eventually be turned into some amazing visual effect. Have you paid attention to the tracking markers that are on that high-budget shot though?

Matthew Merkovich has.

Matthew is a highly skilled and seasoned 3D tracking artist who has worked on a ton of feature films and top-tier television. From tracking shots for such films as Minority Report,  Equilibrium, Final destination 2, to TV shows such as Star Trek Voyager,  Terra Nova, and Grey’s Anatomy. In between, are almost endless commercials and ad work — all with rock-solid tracking.

tracking software has advanced considerably, setting up for tracking shot hasn’t

Tracking software has really come a long way in a short amount of time. There have been huge advancements in technology, that is attainable to pretty much anyone. As an example, SynthEyes is an amazing software for camera, object, geometry and planar tracking — and it is completely affordable.

The thing is, with the fast-paced advancements in tracking, people are still laying out markers as they did on day 1. If you have ever seen a green screen littered with orange, pink or dark green tape in a variety of shapes and sizes, this is where the discussion is centered.

Matthew’s campaign’s message is that that elaborate tracking makers are not needed any longer. I spoke with Matthew in the hopes of clarifying, and spreading the word for his mission to tone down tracking markers on set.

Where did the idea of using orange and different marker types such as crosses and patterns originate?

That is a fantastic question, and not just because I ask it all the time. I once got pulled onto a movie by the producers to help fix a VFX budget gone out of control and I asked the owner of the VFX company contracted to do the work why there were these huge hot pink Xs all over the blue screen footage she supervised. She rolled her eyes at me and said, “That is an industry standard best practice and I’ve been doing this with [name of renowned VFX supervisor redacted] for years!” This was a movie with a 20 million dollar budget and Academy Award winning stars.

When I ask younger people why they are placing these big plus signs on their low budget pictures, I hear, “Isn’t that what you are supposed to do? Our VFX guy said that’s what we were supposed to do.” My conclusion is that they have no good reason for these big +s or Xs.

I’ve researched this historically as well. I cannot find the big-orange-X-on-green-screen patient zero. Having personally done VFX since my first credited shot on the TV show Unsolved Mysteries way back when, I’ve seen solutions to specific problems turn into generic solutions many times. I can imagine somebody in the 1990s came up with the big garish colored X to solve a specific tracking problem and it just stuck. 3D tracking software didn’t even exist back then, but that’s when I began seeing this phenomenon, so I could conclude this was to solve a 2D tracking problem.

Later, in the early to mid 2000s, I began seeing shots with black circles with white triangles and all manner of crazy geometric shapes. Just googling “tracking marker” gave me this as the first search result…

 

tracking-markers-search

 

in 2004, I was at Asylum VFX and had many discussions about these weird new patterned markers with a coworker, math Phd Dr. Mathew Lamb. He said these features best “stimulated” the Boujou auto tracking algorithm. In 2016, placing markers like this in generic footage is no longer really a thing and I’m personally glad to see that Boujou has mostly gone the way of the dodo, though some people still use it. I can only guess that is a sunk costs issue. I still occasionally see these kinds of markers though. I’ve never needed them, ever.

People have no idea that tracking a knuckle on a c-stand is just as easy as tracking the tennis ball they cut a hole in to mount on that very same c-stand.

I guess that is what my one man campaign is all about.

 

You are also quite vocal about taking camera data while on set. Why do you think this practice has become irrelevant?

I just got lens notes on a show I am working on now. Everything came from a RED Dragon shooting a 16mm Primo V lens. When I tracked the three shots, the calculated lenses were 16.534, 16.536, and 16.321. I get results this accurate every single time, with any lens you can throw at me. These are calculated lenses! I did not give my tracking software, SynthEyes, any clue from the camera notes.

I’m working on some new tutorials about this right now, going into the subjects of lens breathe and camera and lens manufacturing error tolerances to explain why the focal length printed on the lens barrel is merely a very close guideline. There is also the factor of human error. Is that camera report accurate? Did the camera operator bump in on that zoom ring and not tell anyone? How do you even take a focal length note on a 70-200mm lens?

Bottom line, my calculated lenses are going to be more physically accurate than forcing a potentially wrong lens into a math problem.

 

What are some of the best practices for preparing to track green screen shots?

I was overseeing nearly all the VFX on a TV show a while back and I did a slapdash guide for production on how they should place tracking markers. The video was really only intended for them, but I am revising it to be more thorough. Until I finish that video, here it is:

And here are my notes from that page with a few small revisions:

As you can see, there is very little reason to add tracking markers most of the time. But I thought I should add a few important points for when you do need them.

  • Always DOTS.
  • Never X’s made with colored tape, or checkerboard patterns, or triangles, etc. Just circular dots.
  • Preferably small white dots on a dark background. If your track is in a white environment or a white object, black dots will work, but will disappear during whip pans. (I don’t make the rules of light physics; I just have to live by them.)
  • The dots should be just big enough to be visible. If you are shooting a lot of coverage, close medium and wide, let the wide shot be the guide for how small they should be. Make them just barely visible in the wide. I really don’t overthink this. I rip off half inch squares from a tape roll and call it a day.
  • You typically need to see at least nine dots on screen at any point to get a good track/match- move. The dots can leave and re-enter frame during camera moves, but you still need to see at least nine dots at any given time. That just means you need more dots off camera that come on when you pan and tilt. Nine is a bare minimum. On some tracks, the software will detect scores or hundreds of features to lock onto. The more trackers, the more accurate the 3D track.
  • And move the camera, if that’s what you want! “We only moved the camera a little to make it easier to track.” All you succeeded in doing is making your shot more boring. >Obligatory winky face goes here.< Big moves or little moves are no different in difficulty. However, fast moves with lots of motion blur are harder.
  • Crazy shapes are useful when shooting crazy, whip panning, hand held shots. The markers are going to become big motion blur streaks so having many crazy shaped patters helps disambiguate the tracking markers…I suppose. Frankly, I would still prefer plain old dots on a green screen.
  • Circular dots. CIRCULAR DOTS! CIRCULAR DOTS!!!
  • And if you need to throw up a lot of tracking markers fast, for example on a green or blue screen, get a cheap laser with diffraction grating. Blue lasers are great for blue screen. Likewise, green lasers for green screen. Too bright? Unscrew the cap and jam some ND filter in there. Boom! A field of tiny dots to track. They should be just bright enough to be visible and you won’t need to spend a lot of time doing roto or paint to clean up your edges. Of course the lasers won’t work if there is any atmo on set. Smoke machine? Forget I said anything! Break out your digi-green tape roll!

I’ll add that the reason you shoot green screen is to pull keys. Obvious, right? No one seems to remember this though when placing tracking markers. They place these big orange Xs and then a blond actor’s hair crosses that marker and your two hour comp turns into days of hair reconstruction, roto, and headaches.

 

What do you recommend someone do when they see someone going overboard with markers?

Yell at them! 🙂

12 comments

  1. Rich

    The best part is the awkward ending….

    -1
  2. David Shere

    Different “crazy” shaped markets are used so that when you are in a close-up on a greenscreen, you know which part of the greenscreen the actor is in front of. And hence, know which section if the DMP to put in behind. Orange Mathers are used so that when you key the greenscreen you can still pull some detail from the green channel but have tracking info in the red channel.

    • David Shere

      That should read, “Orange markers”

  3. Brilliant. Nice Matt. hahah hope it actually gets in front of the people who need to see it.

    • Thank you so much, Kim! Working on getting it in front of the people who need to see it right now. The new tracking marker guideline video I’m working on is really more for my producer friends than my VFX friends, who mostly all get this already. 😉

  4. Jon

    Boujou has gone the way of the dodo? Why am I always the last to know? What are you using these days instead?

  5. Mark Weingartner

    Been putting up tracking markers since 1994. Mostly tentpole features
    I have always favored ultimatte blue on green and ultimate green on blue screens…small squares (or “L” s turned in different directions if lots of fast pans and likelihood of a marker only being in one or two shots so you can differentiate them. Crosses make no sense – as soon as they are out of focus their complicated shape becomes a little cloud of different chrominance. With key able markers you can still find them for the track but if you do have actors crossing them you can key them.
    i thought this was clever in 1997 or so when I started doing it but it doesn’t seem to have caught on. On-set supervisors were always happily surprised when I offered it up.

    The more time and money you have in post the less it matters but why not give people the easiest track AND the easiest key?

    Never understood the complicated fiducials in a world shooting at f/2… they are just blurs anyway when the actor is next to camera and the screen is forty feet away.
    I try to make markers just big enough to be found in the wide shot. – that is sort of situational but you should be able to figure out what you need. If the shot is wide enough to have a bunch of foreground set detail then – voila – you don’t need to worry so much about the markers for that shot – you already have enough detail to solve the track.
    I have no idea why people put them crossing where the actors heads are – why make hair any harder than it already is? If the shot is so incredibly tight that you only have the actor’s head and a wee bit of green or blue around it – well, chances are you can pretty much slide the backplate to where it looks good. I’m also a live action DP and we move actors around in real life all the time, why not slip the bkg – a bit to make nice shot?

    If it’s an ILM show I never argue – in fact it is generally good to avoid arguing about religion… they’re used to fixing the problems they create with too many complicated markers… of course I haven’t done one with them for a while – maybe they’ve moved on.

    • Yes, yes, yes Mark!

      The only very real world reason I can imagine for markers going behind actor heads is when you are shooting for a day or ten on the same green screen stage and will have coverage ranging from masters to two shots to tight close-ups, etc., etc. Markers get placed to cover any eventuality, so how about making them easy to paint/filter/key out, right?

      Obviously a short discussion like above can’t cover everything and certainly there is plenty of opportunity where people could tell me, “You are so wrong about…[fill in the blank].” Of course I’m wrong! I’m just happy to get the conversation started about what the default settings should be.

      And FWIW, I like digi green on chroma green and digi blue on chroma blue. With the 2D tracking technology today, I can nearly track green and blue screen with absolutely no tracking markers. Just don’t ever tell anyone I said that! 😉

      • I think a lot of the time markers behind heads comes from multi-camera setups. You place markers to try and get them optimal for 2 or more cameras, one inevitably on a telephoto lens that can’t see any of them (or which positions a marker right in someone’s hair, when they do an un-anticipated slider move right on action) and its the worst of all worlds.

        I think this why some of the crazy tracking marks exist. Its tough when you have to place marks for cameras at multiple focal lengths. I favor green LEDs because unlike tape marks, they remain easy to see (instead of harder) when they go out of focus, because of the bokeh. Glowing marks present their own problems, though, so I have everything from green and blue tape to some of the ‘weird’ marks to lasers in my kit. It helps that back when my company was small, I did the 3d tracking myself, so I know what kinds of things will help or hurt my matchmover. The most accurate line in the whole article is “I’ve seen solutions to specific problems turn into generic solutions many times”. So many productions want some sort of silver bullet solution that they can just do without thinking critically about it, or base their entire philosophy of shooting vfx on some offhand remark they overheard a vfx supervisor say years ago under very specific circumstances.

        I always tell the shows that I’m supervising to NEVER place tracking marks when I’m not on set. Either the shot is complicated enough that the VFX supervisor should be there to place the markers based on the specific situation, or we can make due with a tricky track from physical landmarks and the potential extra cost to do the work will be less than the supervisor’s day rate. Whenever the production tries to get clever, their tracking marks end up being both useless for tracking purposes and expensive/difficult to roto, so its lose/lose.

        • Right on, Lawson. Agreed on all points! Multi cam TV is the worst for this “protect yourself for any eventuality” approach to placing markers. And I didn’t even get into monitors for screen displays, for which I could write an academic thesis at this point. Multi cam control rooms in crime procédurales became a big part of my life for a while there.

          And speaking of useless marks from production, How do you like the green tape plastered on the bezels of those monitors, eh? Almost as good as that one big X right in the center of the display someone though would be useful! >Ack!<

  6. Stephen

    Thanks for the article! I always thought the logic of an x or cross was to aid in calculating rotation. I understand rotation is also tracked by the relative angle of multiple points to each other, but I didn’t feel the logic of the dots was fully explained for the emphasis it was given.
    Cheers!

  7. There’s no avoiding tracking markers behind actors in a TV show shooting with 3 cameras. You’ll have your wide on a 24mm that doesn’t need markers because you can track the set, a 75mm cowboy shot that dollies with the actor as he walks across the screen, and a 120mm closeup that is just the head and shoulders moving across the screen as the actor crosses set. And you’ll have hopefully 10 minutes between when the blocking is done and the cameras roll to set up markers for any potential camera situation. Such is the nature of shooting a 1 hr episode in 8 days.

    Whenever an artist doing a wide shot complains about how many markers I had in a shot that doesn’t need them, I show them a picture of the three monitors in video village and ask them how they would have handled it. So far, every artist who sees the standard three camera setup has agreed that in this situation, too many markers is better than too few.

    I agree that using a contrasting similar color for markers is best so you can key them out (digi green markers on chroma green screens, for example) as opposed to orange markers on blue screen. Every time I go to a TV set and see orange markers, I know some feature guy who’s used to an army of roto artists has been there before me. TV people hardly ever make that mistake.

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