Mocha VEGAS - Getting Started

Now we have a shape drawn, we can track right? Not yet!

In this example we have a problem. The screen has reflections which will throw the planar tracker off!

Because trackers can’t determine what is a plane and what is a reflected object like humans can (yet), we need to tell Mocha to ignore the problem areas.

First, turn on the mattes for the layer. By default this is Alt+1 or you can find it under the View menu here:

This shows the matte create by the spline:

We now want to cut a hole in the matte by adding a new spline to the existing layer. For this we need to use one of the Add Spline to Layer tools.

If you press and hold down the mouse button on any tool with a small arrow in the bottom right corner, you will get a series of other options related to that tool.

We want to choose a tool with the + sign next to it. In this case, we’ll choose the X-Spline pen tool "Add X-Spline to Layer".

Now we can draw a new shape in the layer to cut a hole on the screen, cutting out most of the reflections. Anything in the white matte area will be tracked. Anything outside the matte area will be ignored.

You want to keep a little bit of the screen inside the matte. A small amount of edge will help define the plane while ignoring most of the problem reflections.

We can also tighten the curve of any X-Spline by pulling on the handles of the control points. A left click drag on a handle will change the selected points. A right click drag will change the handles of all points.

But there is still one glaring problem. The large finger swiping at the screen.

We need to roto out this finger for two reasons:

To roto the finger, we’ll start by selecting the X-Spline pen tool to create a new layer (NOT the "Add x-spline" tool):

Then draw a basic shape around the finger:

We can then refine and smooth it out using the handles like we did before:

Note we’re once again creating a larger shape rather than following the edges. We’ll refine the shape later when we want to cut out the finger for compositing. For now, we want a bigger matte to make it easier to track.

Note that every time we create a new layer, it appears on top of the layer stack. In this case the finger layer we have made is on top of the screen layer and will matte out the layer below.

Layer order is very important. Layers higher in the stack obscure layers that are below. Think of it like a distance hierarchy:

Let’s rename the layers while we’re here to make it easier to see what’s going on. Double click on any layer in the layer stack to rename it.

For clarity, we’ll use:

If you now select the "Screen Track" layer with the mattes still turned on, you’ll see the "Finger Track Matte" layer is also cutting a hole in the bottom edge.

Now we have the two layers we need, we can start tracking.

You can track multiple layers at once as long as they are set up correctly. The little cog icon next to each layer name defines whether the layer is going to be tracked or not.

Depending on what you’re going to track, you will want a different type of Motion analysed.

In our example, the finger is moving organically and has a lot of motion blur so we’ll reduce the motion types and just focus on changes to translation, scale and rotation. The screen however needs to be very accurate, so we want all motion types including Perspective.

Select each layer and set the track motion types accordingly:

Now we can start tracking!

In the Essentials panel you’ll see two arrows with a little T in them. These are the track forwards and track backwards buttons.

You can track in either direction. Let’s start by tracking forwards:

As you track, the timeline playhead will move and you’ll see the splines update as the objects you’ve drawn around are recognised and updated each frame.

However, at some point you will probably hit this message and everything will stop:

This message just means "We couldn’t find the thing you were tracking in the next frame". Usually, this is because:

In this case, the finger has become really blurry during the swiping part of the motion:

Since we only care about the spline part of the finger layer and not the track, we can finish the finger portion by just keyframing the spline points by hand.

Move the playhead a little further along the timeline and adjust the spline points so they cover the finger in the same way until the finger is no longer covering the screen.

Notice that every time you adjust the shape around the finger, a new spline keyframe is created:

When you have finished tracking forwards, go back to where you started and track backwards.

You can stop the track when the finger moves off the screen again and we can trim this layer as it is no longer needed.

Sometimes you don’t need to see a layer for the entire timeline. For example, in this shot, we only care about the finger when it is covering the phone.

You can turn off layers so they no longer contribute to a scene by using Layer Ranges.

Go to Layer Properties tab that sits next to the essentials tab on the left hand side of the GUI:

Next, move the playhead to where the finger is off the phone screen and click the In point:

Do the same at the other end of the timeline, this time clicking the out point. When you’re done you should see two small tabs on the timeline indicating where the layer ranges are set for the finger layer:

Now when you move the playhead outside these areas, the finger will not show up and won’t contribute to the track.

Now we have the phone tracked, we want to make sure the surface is lined up to the right spot and tracked correctly.

If you haven’t already, turn on the Surface tool again, and make sure the corners are lined up exactly with the screen corners.

You can also turn on the grid tool to give you a larger view of the tracking motion and spot any jitter.

The grid placement is directly linked to the Surface and can be adjusted by moving the Surface corners, edges or center point.

Playback the shot and check for any problems.

Another way to check the track is to insert a built-in clip that will help visualise the overall movement. This is available in the Layer Properties as a dropdown:

In Mocha Pro, you can import your own or use layers in VEGAS, but here we have a simple list of clips to try out.

For example, here is one of the Grid Clips:

Scrub the playhead with the mouse or playback the shot and see how the clip matches the screen.

If you see any issues, you might need to reposition your Screen Track spline to capture more of the phone edges, or check to make sure the finger matte is completely covering the finger.

We won’t cover the AdjustTrack module in this quickstart guide, but if you want to know more about adjusting a track after it is completed, see the Essentials Course.

Now we have a screen track we’re happy with, we now need to make sure the finger swiping across the screen is correctly composited on top.

To do this, we’re going to need to make a refined roto mask around the finger.

There are two ways to do this:

In general, we recommend option (2). Keeping all your different layers as they were originally used is a good practice so when you come back to a shot later you can see the work that was done.

Select the X-Spline Pen tool again. You may need to choose the dropdown to select the New X-Spline instead of add to X-Spline.

Now draw a tighter spline around the finger on a frame where the finger is most clearly in view. Follow the edge of the finger as closely as possible:

Right-click one of the handles and pull, smoothing out the spline curves:

Rename this layer Finger Mask to make it distinct from the Finger Track Matte.

To save some time, we’re going to use the existing track we made from the Finger Track Matte.

To do this, select the Link to track dropdown in the Essentials panel and select the Finger Track Matte layer:

You’ll now see the colour in the timeline of the Finger Mask change to the blue "tracked" colour. This means the Finger mask now has the tracking data from the other layer.

Linking the track isn’t necessarily going to do everything though.

If you now scrub through the shot you’ll see some obvious problems where either the track isn’t positioning the finger mask correctly, or even where there is no tracking data at all.

The is when you need to refine the finger mask by manually adjusting each control point. Mocha keyframes the whole spline automatically when you move a point.

Note the spacing of the keyframes. Try to only keyframe at extreme points in the movement of the spline so you don’t create too many keyframes.

More keyframes means more work for you, so follow the basic keyframing methodology of:

This way you reduce the amount of keyframes you need to make over time and reduce the amount of work you need to do.

Keep refining the Finger Mask points until the finger is rotoscoped for the portion of phone covered by the finger

Once you have your track and roto mask, it’s time to use it!

Close the Mocha VEGAS GUI and save when the prompt comes up.

You should now be back inside the VEGAS interface.

In order to use the tracking data, you first need something to apply it to.

Drag the phone screen PSD file from the VEGAS Project Media window into the video track above your footage layer:

Make sure the video track layer is the same length as the phone clip in the layer below.

The final thing to do is place the finger back on top of the screen so it looks like it is resting on top.

Now when you scrub or play the shot you should see the finger composited over the screen.

This is because the plugin is rendering the mask and cutting the finger out over the top. You can then adjust blending and opacity to get the screen how you like it.

If you don’t want to render the matte directly from Mocha you can also create Bezier splines inside VEGAS.

Now instead of a rendered matte you will see VEGAS masks on the layer instead, with generated keyframes:

You can now feather these masks manually or adjust them how you like separately from the Mocha VEGAS effect.

And that’s it! You now have a functional composite using Mocha tracking data and masking.

If you’re unclear on any part of the process, we highly encourage you to watch the video at the start of this article, then follow up with the Essentials Course, which goes into much more detail.