Guidance on the Corner Pin Studio

I have to track and insert into several computer monitors, and am hoping Corner Pin Studio will work here. I’m not clear on the concept of Foreground and Background implemented here. Is there more documentation, and any video demos besides the 2 minute intro? Thanks.

  • Harry

Hey Harry,

I have just finished a tutorial on this exact topic for the Boris FX YT channel, so Peter will be able to let you know when it’s going live. It’s for Media Composer, but the concepts work exactly the same across all the host applications.


Corner Pin Studio has a lot of built in workflow flexibility which can be quite useful, but it’s important to get the naming conventions right. Think of Foreground as the clip you’re going to insert - i.e the clip that will be deformed by the pin. Think of the Background as the layer you will track, e.g. the shot of the monitor/phone/tablet/billboard/etc - the one whose motion you will analyze so that the Foreground/Insert stays locked to it. (If you want to composite the Insert layer BEHIND a tracking layer that was keyed/masked, you do that via the Composite Behind option, but the clip you’re inserting is still considered the Foreground and the clip you’re tracking is still considered the Background.)

In most hosts you can apply Corner Pin Studio to either the Foreground clip (and then select the right Background track) or you can apply Corner Pin Studio to the Background clip (and then select the right Foreground/Insert layer). Once you apply the filter and choose the right foreground/background layer, the next step is to place the four Corner Pin point picker locations on the right positions for your current point in the timeline. Then launch Mocha and the default shape/surface will align with those initial starting points that you set. Go ahead and track as usual in Mocha, fine tune the surface corner locations as necessary, and apply back. You should see the Foreground/Insert following the tracked Background layer. The rest is then a matter of fine tuning the composite/scale/offset/color etc. using the rest of the controls.

Does that help you get started? More detailed tutorials will be added soon.

We’ll be posting Kevins new Corner Pin Studio in Avid tutorial shortly. It’s a great in depth look at how to use this filter to achieve exactly the result you’re looking for.


Thank you, guys. Kevin, I’m very much looking forward to your tutorial. It couldn’t come at a better time. Attached is my current task, the first shot in a sequence full of these monitors. Monitors

The shots are seemingly all hand-held, with people walking through on a regular basis. Yikes!

  • Harry

There are very many Mocha tutorials on the Boris FX website and the knowledge is easily translated to Corner Pin studio. Depending on the motion of your shot, you may be able to track just one montior and apply (link) the tracking data for each montior. Or possibly one track for the first 6 could be used, one for 7-12, etc. Montiors on each row are most likely all on the same relative plane.

You will want to avoid the blue screens and focus Mocha to track only the edges of the screens.

Lastly, with 12 screen comps, this is most likely a candidate to finish in a compositing app like AE, Nuke or Flame with Mocha tracking. Not to discourage you, it can be done in Corner Pin Studio and Primate on an editing system like Avid or Premiere, but will not be very interactive or enjoyable.

Hope this helps.

Thank you for the advice. I found putting the insert on the top layer and on that applying the effect to be counter-intuitive. The terms ‘foreground’ and ‘background’ are a bit misleading. ‘Insert’ would be more precise and consistent.

I ended up using mocha Pro in AMC. Starting with the background plate, added mocha Pro, tracked the shot, then created one of the screen inserts. Into that I imported the .mov file, rather than use the layer below as insert. I then copied that clip to a lower layer, and repeated the insert with a different monitor. With up to 13 layers of mocha, my system ground to a halt. So I did some video mixdowns to simplify the processing. Once the screens are created, I place a clean layer of the BG plate on top and key it with Primatte.

This worked until I upgraded to mocha Pro 2020. My imported .mov insert screens went black. Upon opening up in the effect editor / mocha interface, there was an error message about the media being corrupt (I reported this error in the mocha Pro forum). Downgrading to 2019.5 restored the video imports.

I am only doing these as temps to get the producer to sign off on the design of the screens. Ultimately, a professional will actually make these shots.

BTW, I’ve looked at every mocha Pro tutorial I can find on the Boris site, Youtube, Vimeo. Although extremely helpful, it takes time for me, an editor, to absorb the concepts (tracking, insert layer, surface tool, grid tool) and how they work together. At times I track a shot, create an insert, then get wildy off results. It baffles me when the surface moves differently from the insert shape.

The hardest part, I think, is understanding how to correctly track a shot. Most of the shots in the demos are relatively straightforward. The shots I encounter seem much more complicated. Shots that are handheld, with two people walk through the frame, at times completely blocking the frame and surface I’m tracking. Or a green card with no tracking marks that should be a photograph, but is variously blocked, curled and moved, making it seemingly impossible to track.

I love the challenge, though. And greatly appreciate the feedback and support from BorisFx.

  • Harry

I completed the temp screens on about 10 shots, with between 2 and 13 screens per shot. Mocha worked extremely well. But once you get 7 - 8 layers of mocha shots, the Avid gets very slow. But it worked.

My question is how would I make the screens more realistic? Doing a basic replace screen with a Quicktime file shows a very bright and sharp screen image. What should I add to blend the screen better?


  • Harry

Generally screens are much dimmer and less saturated than you would think. If the screen is black than you can typically do a comp set to “screen” and bring opacity down. Since your screens are already blue, your best best is to color correct and reduce the brightness and saturation. Then add a small blur to match the shot.

The final compositor might choose to key the blue out and put screens below which will give more options.

Sometimes very subtle fake reflections, lights or glows can help sell the shot as well.

Thank you. H

  • Harry