Align Surface headache, Corner Pin error.

Apologies in advance if I overlooked the solution to this, I’ve been searching around for a while now.

So I’m trying to use the technique from Andrew Kramer’s Subsurface Skin tutorial, when I think my planar surface looks right, I goto the last frame and align the surface, copy the tracking data to clipboard and paste on a solid layer on the first frame. Then everything turns to crap for me.

In the footage I’m using I have an actress that is turning her head from left to right multiple times and the camera man is moving a little bit as well. It’s not a closeup of the face either. Before I use align surface it looks like it’s following the face pretty well but does stretch and distort a little despite my efforts with AdjustTrack.

After I align surface and check out the solid in After Effects, the solid completely disappears in some frames and doesn’t seem to be following the face well at all. If I hit space bar to preview playback I get an error in After effects that says “Corner Pin cannot allocate a buffer larger than 30000 pixels in either dimension.” 25::56

Any suggestions? Different workflow?

I’ve also noticed I can’t undo in AdjustTrack which has caused some headaches. It seems like it would be a lot easier if I could just animate the planar surface tool instead of the tedious clicking of the left/right/up/down buttons.

I’d also love to know how the Black Swan team managed their skin effects with so much motion going on.

How big is your solid and what resolution are you working in?

Make sure your insert and your base footage are the same comp size to get corner pins to paste right in AE, or use align surface: Boris FX | Align Surface and Mismatched Resolutions

Hi Mary,

I’m working in 1920x1080 and my solid matches that size. As far as I can tell all the sizes match. In this case my insert is a collection of vein images so fitting them to comp size works but doesn’t allow as much control as I’d like.

If you meant my operating system resolution, I’m working at 2560 x 1440 with multiple monitors.

My main issue is that when I use Align Surface, After Effects throws out that error when rendering and when scrubbing through the footage I can see the vein effect completely vanish during the more extreme turns of the head. I’ve seen multiple tutorials that use the Align Surface method and am at a loss as to I’m missing.

EDIT: So it appears the problem is that when I use the Align Surface feature, during head turning the surface is getting stretched to extremes. I was trusting that if nothing extreme was happening before using Align Surface that it would be ok, apparently not.

Ah ha! That is the clue I was looking for. If the veins are disappearing, turn on your surface tool and see if it is disappearing. If it is, the surface is going behind the camera. Try tracking shear only instead of perspective during the extreme turn or using manual track to get past it. It is likely that the track is bad.

Let me know if that fixes your issue for you.


Turning off perspective helped improve some areas, but didn’t get rid of all the problem areas. I just attempted using manual track mode to fix problem areas, then looked back at the other frames only to find what looked good before was completely messed up. I literally watched my x-spline float up and away, then decided I need to go for a walk.

This face is literally looking right, left, down and up with the camera moving in as well. Tried tracking different parts of the face to try to get a better planar track without much luck so far.

It sounds like you have a very complex track. I understand the need to take a walk after dealing with such a shot. Try instead of tracking the face for the entire shot, breaking it up into smaller tracking sections and blending tracks into one another where the face turns away from camera. If you track from areas where the section you are tracking is most parallel to the camera to areas where the face is the most angled away you can blend those two layers together in the areas where the planar data is the most pushed in perspective.

Deceptively complex I’d say. I tried tracking small areas of the face which mostly failed, had some areas oddly shrink. Think it’s because the actor’s face is small relative to the overall screen.

Any tips for blending different tracks together? I’m going to try that next. When it comes to manual track, are there no hotkeys for switching and deleting keyframes? Seems like a lot of clicking, would be nice to select multiple keyframes to delete at once.

So far the most annoying thing is align surface. I can get what looks like a good enough track on the planar surface, then use align surface and find out that has major issues.


Well, you don’t have to use align surface, you can also simply make the insert for the corner pin the size of the comp and then it will size correctly onto the face. I blend tracks by finding 4 points I can find again and aligning the corners of the corner pin to those areas. You can also simply turn the surface tool on for each layer and make sure they line up.

If there aren’t many pixels on the person’s face to track, that is absolutely going to be hard for mocha. Try using adjust track to help correct some tracking problems as they arise. You can also try tracking without perspective and using shear only, if it’s small in the screen it might read fine.

For hot keys, you can find those here: Boris FX | Mocha V5.6.0 User Guide

You can customize them as well. There should be keys for adding and removing keyframes.


Found the hotkeys I needed, delete keyframe oddly was unbound by default.

Now I’m convinced I’m running into some kind of bug. I went into manual mode and deleted a bunch of keyframes only to see the entire planar surface leap out of position even in previous keyframes I hadn’t touched. My intention was to retrack or possibly delete tracking data for frames I didn’t want to copy if I was using a different layer for those frames.

Perhaps I’m rusty, but as far as I know there shouldn’t be any global changes happening to previous keyframes unless I’m using uber key, right?

Do you have any existing videos on merging tracks? I’ve watched a lot of your videos but don’t recall seeing that technique.

So about avoiding align surface, it looks easy for flat screen inserts but appears to a little more challenging when the effect isn’t meant to fill the entire corner pin area. At first I was trying to get a good planar track which seems to require tracking more than just the area I want to apply the effect to. Could I just use uber key to resize the entire planar surface without retracking or would it be better to just do a new track and set it’s parent to the “good” track?

Thanks for your time, I appreciate it.

You probably aren’t running into a new bug, but the surface tool might be encountering an issue if part of it is going “behind the screen.” This can cause large leaps like that when the data is corrupt. Try tracking those areas with shear only as I had said above. It really sounds like that is what is happening.

You can’t merge the tracks, but what you can do is have several layers of track and “blend” them into one another with hand animation. We don’t have a tutorial for that, but I can put it on my to do list. Essentially, start a new track where the other track ends.

You can get away with not using align surface if you simply make the object you need to corner pin the size of your comp. It’s an alternate workaround that you might have to use if the track keeps getting corrupted by going behind the camera.