Tracking Basics 跟踪基础
Overview 概述
Imagineer’s Planar Tracker technology can provide the same 2D tracking output
as a 1-, 2-, 3- or 4-point track, but does so by tracking planes rather than points.
The key to getting the most out of the Planar Tracker is to learn to find planes
of movement in your shot which coincide with the object that you want to track
or roto.
让平面跟踪发挥最大功效的关键是学会查找与你想要跟踪或者roto物平相一致的动态平面
Sometimes it will be obvious - other times you may have to break your
object into different planes of movement.
经常它是显而易见的，其他时候他可能会再移动的时候分裂你的对象为两个不同的平面
For instance if you were tracking a
tabletop, you would want to draw the spline to avoid the flower arrangement
in the center of the table — it is not on the same plane and will make your track
less accurate.
To select a plane you simply draw a spline around it. You can be fairly loose with
your spline — the Planar Tracker is intelligent enough to discard the pixel
movement that doesn’t conform to the movement of the majority of the pixels
within the shape.
Our tool feature two spline types, X splines and Bezier splines.
In general X splines work better for tracking, especially with perspective motion.
Nevertheless the Bezier Spline is versatile and is the industry spline standard.
Selecting What to Track
Most tracking applications use small rectangular boxes for selecting what to
track. Our tools use splines.
For example if you are tracking the position of mobile phone screen, you would
normally have to look for a point of high contrast that was relatively stable,
with no significant brightness changes over time to get a good track. You may
have to reposition the tracker to another more desirable point half-way through
the track if your original point moves out of frame. This makes point tracking
very complicated.
With the Planar Tracker you simply draw a spline around the screen as shown
below.
Try this out on the iPAQ demo clip: Use the shape tool to create a shape
around the outside edge of the iPAQ.
You will notice that the shape is not tight
on the edge but actually has a little space to allow for the high contrast edges to
show through, as these provide good tracking data.
Start creating your shape by clicking onto the screen. After the third point, the
shape will auto-close, but you can continue to add points. After you have added
all the points you need, right-click to close.

Dealing With Obstructions or Reflective Surfaces
处理遮挡或反光曲面
In some cases there are parts of an image that can influence the effectiveness of
the Planar Tracker.
在一些情况中，有一部分图形可能影响平面跟踪的效力
To handle this, you can create an exclusion zone in the area
you are tracking.
要处理这种情况，你可以在你跟踪的区域内创建一个排斥地带
For instance, in the iPAQ example we are using, there are frames where there
are strong reflections on the screen.
例如，在我们使用ipaq的例子中，有一些帧里屏幕有非常亮的反光
These reflections can make the track jump.
这些反光可能致使跟踪跳跃
So what we need to do is isolate that area and tell the tracker to ignore it.
Here’s how this is done:
所以我们所需要做的是孤立这些区域以及高速跟踪器忽视这部分
方法如下：
1.First select the initial layer you created.
首先选择你最初创建的图层
2.Second, select the add shape tool to add an additional shape to the current
layer, which selects the area you want the tracker to ignore.
然后，选择加形工具来为当前图层添加你所要忽视区域形状，
3.Draw this second shape inside the
screen. Note that both splines have the
same color, which is an indication that
they belong to the same layer. Also you
will notice in the Layer Controls panel
that you only have a single layer.
注意所有的样条曲线具有同样的颜色，这表示他们属于同一个图层。
4。Lastly, using the handles at each point, pull
them out to create a straight cornered
shape.
最后，使用手柄调整使得每个角呈直角形状
By turning on the Mattes button under
View Controls you can see the area that
will be tracked.
在视图控制栏下方打开mattes按钮，然后你会看到将被跟踪的区域


Before You Track 跟踪开始之前的工作
Various tracking parameters can be accessed by selecting the Track tab.
各种跟踪参数可以通过选择跟踪标签进行读取
On the left hand side of the Track tab, you will see two sections:
在跟踪标签的左手边，你将会看到两部分内容
Motion and Search Area. 动作和搜索区域
Motion allows you to define the type of motion the tracker should be
calculating and whether it should expect large motions (specified in the Search
Area) or only small motions (up to about 3 pixels shift per frame),
动作允许你定义将要计算跟踪的动作类型，以及是否期望产生庞大的动作（特指在搜索区域）或只是轻微的动作（多达3像素偏移每帧）
which is faster and great for tracking small jitters to be stabilized.
这使得跟踪更快更好，不抖动非常稳定
The settings under Search Area allow you to control how large a motion the
tracker should expect, similar to the way you would increase the size of the rectangle for a point tracker to handle faster motion.
在搜索区域下的设定允许你控制最大期望的跟踪动作量，类似于点跟踪时增加矩形大小来操控快速的动作
If the object in your shot is moving significantly and you are working on a large 2k–4k image, you may wish to manually enter some large pixel values.
如果你目标中的物体动作非常明显而且素材高达2k-4k分辨率，你可以手动输入一些大像素值
1-, 2-, 3- and 4-Point Style Tracking
If you would like to track just x,y position information, like a traditional point tracker, then select only Translation in the Motion section.
If you’d also like to track the Scale and Rotation, simply check the Motion mode to include Rotation + Scale.
Keep in mind, because this is a Planar Tracker, you do not have to track two
separate splines.
记住，因为这是平面跟踪，你不需要跟踪两条分离的样线
Unless they are on the same plane of movement, this will
actually make for a poor track.
除非其在一个平面中移动，这会导致跟踪不理想
Trust the planar tracker to derive the Rotation
and Scale based on pixel movement within the spline.
4-point or corner pin tracking is where the Planar Tracker really begins to shine.
You can achieve more accurate tracks faster than you would think possible.


Tracking the Spline 跟踪样条线
Before we move on to performing the actual track, we first
need to adjust a couple of settings depending on the
movement in the clip.
在我们执行当前跟踪工作之前，我们首先需要调整几个设定
In this example, keep the default motion settings Translation,
Rotation + Scale and Shear, which is the equivalent of a 3-
point track.
Track the plane selected by pressing the Track Forwards button on the righthand
side of the transport controls section.
Stop the track and adjust the shape if it doesn’t seem to be tracking properly.
You may keyframe the spline shape so that it tracks only the planar region of a
shape by adjusting the shape and hitting Add Key in the keyframe controls
menu.
你可以通过调整形状和在关键帧控制菜单中添加关键点为样条线形状设定关键帧用以仅跟踪形状区域的平面
Keep in mind that no initial keyframe is set until you first hit Add Key or
move a point with Auto-Key turned on.
记住当自动记录帧打开时没有初始帧设定直到你第一次添加关键点或移动点
Checking Your Track 检查你的跟踪
The spline should be tracked in addition to the clip being cached to RAM.
You can play it back and get an idea as to how the track went. Feel free to change the playback mode in the transport controls to loop or ping-pong your track.
Another trick you can do to check your track is hit the Stabilize button in the
View Controls.
Turning on Stabilize will lock the tracked item in place, moving the image to
compensate.
In the track module, stabilize view is a preview mode to check your track. Actual
stabilization output is handled by the Stabilize Module, explained in the
Stabilize Overview chapter.
You can check the accuracy of your planar track by turning on the Surface and
Grid overlay in the View Control panel. Drag the corners of the Surface overlay
(the dark blue rectangle) to match the perspective of your tracked plane. If you
play the clip, you should see the surface or grid line up perfectly with the plane you tracked.
IMPORTANT CONCEPT
The Surface and Grid have no keyframes; they are
simply guides that let you check the accuracy of your
track. Note that the position of the Surface WILL affect
the exported tracking data, so you MUST position the
corners of the Surface before exporting tracking data.
Next click on the Surface button under View Controls.
When you turn on the surface
you will see the blue box that
represents the 4 points of the
corner-pin. Right now you will
see that it is not lined up with
the screen.
By selecting each corner one at a
time you can adjust the surface
area to cover the area of the
screen.
The Grid overlay should line up with the
plane you’re tracking and move with it as
you cycle through the clip.
网格覆盖将会在你跟踪的平面排列以及跟你的裁剪一起运动
You can change
the density of the grid by adjusting the X
and Y grid values in View | Viewer
Preferences:
The grid overlay can give you a quick
representation of the accuracy of the track.
The Trace feature allows you to
see the position of the planar
corners over time. Skip allows
you to work with only every nth
frame, useful on particularly
long roto shots where the
movement is predictable.
IMPORTANT CONCEPT
When you track a layer, the mattes of any active layers
above the layer itself are subtracted from the matte of
the layer and hence influence the area being tracked.
To keep your tracking predictable, it is recommended
that you keep your tracking layers on the top of the
stack unless you specifically wish to use other layers to
subtract from the tracking area of layers beneath it.
To monitor what the tracker “sees” as a tracking area, select the Track Matte
button in the view control.
Importing Mattes
There may be instances where you have already created mattes for one or more
objects in the shot, for example using a keyer or another roto tool that would
help you isolate areas to track. You can import such mattes by creating a new
layer and then using the Matte Clip setting under Layer Properties to assign it to
the layer.

situations. Simply click the New Ref button to create a new reference point for
the selected corner.
You cannot keyframe the Surface — only the Reference
Points. The original track and any refinements you
make in AdjustTrack cause the Surface to move
however.
Working Backwards
Every so often a shot will come along that is easier to track backwards than
forwards. This is fairly simple when running the tracker backwards, but
introduces some rather obtuse concepts when keyframing is involved. This is
why there are two “New Ref” buttons provided. If you are working backwards
and wish to set a new reference point, you will probably want to use the “<-
New Ref” button instead of the forward-thinking “New Ref ->” button.
Because keyframing “thinks”
forward, hitting “<-New Ref” will
not create new Master Reference
points on the current frame, but will go backwards in time, looking for any
existing keyframes and set new Master Reference points on the frame directly
after. For example, if you decide to create a new backwards reference point at
frame 20, a new master reference will be created at frame 21.
Some people may be more comfortable doing this manually by moving the
playhead themselves and using the traditional “New Ref ->” button. Others who
do a lot of tracking and find themselves working backwards often may find the
backwards-thinking New Ref button helpful.
About Master Reference Points (the red X)
Every Reference Point has one frame in which its initial placement is determined
without causing any adjustment to the track. This is called the Master Reference
Point; if you step forward or backward in time you will notice the red X change
to a red dot.
The red X indicates that this particular frame is the
starting point for calculating adjustments. Moving a
Master Reference Point will NOT change the tracking
data.
Go ahead and experiment - move the Reference Point
when it is a red X (a Master Reference Point). You will
notice the Surface isn’t adjusted at all. Step forward a
frame and move the same point - this time the surface
will move because you are now adjusting the track.
Changing the Master Frame for a Reference Point
By default, the frame in which you create a Reference
Point is its Master Reference frame. This Master
Reference can occur on a different frame for each
reference point. You can change the Master Reference
frame by selecting a Reference Point, going to the
appropriate frame and hitting the “Set Master” button.
You may set a new Master Reference Frame for all active
points by hitting the Set Master All button.
Selecting Different Reference Points
One method for selecting different reference
points is to hit the “Next” button.
The next button simply cycles through the
active reference points for that frame. More
fine-grained control of reference points can be
obtained through the Nudge control panel,


described below.
Deleting Reference Points 删除参考点
Deleting Reference Points is done by selecting the point you wish to remove and
hitting the delete key. If there are multiple Reference points on a particular
corner, the preceding Reference Point will be extended through your time line
until a new Reference point is encountered.
Nudging Reference Points
The Nudge section allows you to move Reference points in 0.1 pixel increments,
much more fine grained than would be possible by dragging the points
manually. You can easily select any active Reference
Point by selecting one of the corner buttons in the
Nudge section.
If you hit the Auto button, a tracker will attempt to
line up the selected Reference Point based on its
position in the Master Reference frame. The Search
Region Size and Maximum Motion parameters can
be set in pixels in the Auto Nudge section.
You can quickly select any corner by using the Corner selector buttons in the
Nudge control panel. In the image below, the user is selecting the upper right
corner in preparation for nudging operations.
View Options
The AdjustTrack tab has a View section for cleaning up your
AdjustTrack workspace. Deselecting the Inactive Traces
button will cause the display to hide the traces of the
inactive Reference Points. This is helpful if you have a corner
with numerous Reference Points offsetting it.
Deselecting the Unselected Traces button will hide any
Reference Point that is not selected.
Finally, deselecting the Search Area button will hide the
Search Region Size (in Yellow) and the Maximum Motion
search area (in Pink).
AdjustTrack Keyframing
The AdjustTrack tab has a setting that determines
whether keyframes are per corner point or per
surface.
Normally, you would want to keep your corner
adjustments discrete, so that adjusting one would
not automatically set a keyframe on another
corner. In this case, you would want to keyframe by
points. There are some special cases where you
want to create a keyframe on every active
Reference Point when any one of them is
manipulated. For this case, choose the Corner Pin
keyframing method.

Stabilization Overview 固定概述
Overview
The stabilize feature in Mocha V2 uses the data you have tracked to lock down a
moving shot.
You can think of it as the inverse of what tracking does: It moves
the footage around an area rather than an area around the footage.
Stabilization is useful for:
• Removing camera jitter and bumps
• Locking off a shot so it is easier to work with, before restoring the motion
back into the final composition
The Interface Stabilization is a fairly straightforward operation. Once you have selected the
tracked layer you wish to work with you have options to restrict the stabilization
to key details.
Input Tab: Select the clip that you wish to use to stabilize here.
Range Tab: Select the frame range for the stabilization.

Rotoscoping Basics 转描技术基础
Choosing Tracking Parameters 选择跟着参数
Next we choose our tracking parameters, specifically making sure we are
tracking the right type of motion, for example we need to select Perspective for
the side of the car as there is a reasonable amount of perspective change on this
plane.
接下来我们选择我们的跟着参数，特别是确定我们采取了正确的动作跟踪类型，例如，我们需要为车的侧面选择透视跟踪因为这个平面有大量的透视变化。
Select Perspective motion model for the'BMW side track' layer.
为‘BMW side track’图层选择透视动作模式
Select the Shear motion model for the 'BMW front track' layer.
为‘BMW front track’图层选择剪切动作模式
Note: The Track | Motion parameters work
in a hierarchical order i.e. selecting
Rotation + Scale forces Translation to be
selected and subsequently selecting
Perspective forces all Motion parameters
to be selected. Additionally it’s worth
mentioning that the Motion parameters
are keyframable as it can be useful to change the settings for part of the clip.
Tracking
Ensure that tracking is enabled for both
layers, then click the Track Forwards button.


Turning Layers On and Off 打开关闭图层
Once tracking is complete and we have a satisfactory track, we deactivate the
mattes of the tracking layers as we do not want them used in our renders.
One method is to keyframe the Layer
Active/Inactive state in the Curve Editor.
The layer curve in the curve editor is a
constant value of 0 or 1. 0 indicates that
the layer is inactive and 1 indicates that
it is active.
Keep in mind that the Layer
Properties allow you to turn off layer
visibility in the canvas, but don’t affect
the layer Active/Inactive state in any way.
The second method is to set the In and Out
range of that specific layer in the Layer Controls
panel.
The layer will become inactive
automatically before and after the In and Out
points (though you won’t see any keyframes
created in the Curve Editor).
The final method is to right click on
the layer in the Layer Controls panel
or to right-click on the actual spline
itself.
If you right-click on the layer in the
Layer Controls panel you can select to
Deactivate or Activate the layer.
Right-clicking on a spline
brings up a contextual
menu, giving you the ability
to Deactivate the layer
directly from the canvas.
Once a layer has been made
inactive, it will not be
visible in the canvas. To
make it active again, you
must either right-click the
Layer in the Layer Controls
panel and activate it or
change the active value in
the Curve Editor.
Keep in mind that if you have multiple splines on a single layer individual splines
cannot be made active and inactive independently - only the layer on which they
reside has this control.
COMMON ERROR
Deactivating the layers is not the same as merely hiding
the layers using the 'eye' in the Layer Controls menu; it
literally switches the layers off. This is a keyframable
parameter so make sure the value is set for the entire
project.
Adding Your Roto Spline
Once you have a track for a layer we recommend that you add a new layer to
use for the actual roto spline, rather than refining the spline you used for the
actual track as you might need to do more tracking with it later.
NOTE: Autokey should be on such that we are creating a keyframe for the spline
on the frame we add the spline on. This is relevant as we will be refining the
spline on other frames and need to ensure it is locked off on the frame we start
on.
Select the X spline or Bezier spline tool and draw a tight spline around the
object you are rotoscoping. Ctrl/Cmd+drag the Bezier tangents if you wish to
break them. You will see that a new layer is automatically created.
Tip: You don’t want to inadvertently track with this layer, so disable tracking for
the layer by turning off the tracking button (the cog) for the layer in the Layer
Properties panel.
You can also hide the spline use for tracking by turning off the display button
(the eye) for that layer.


every point in the spline.
Green keyframe markers will be added to the timeline to indicate the presence
of a keyframe on that frame. Only keyframes of the selected point will be
shown.
Try to switch on Autokey mode and go to the last frame of the shot. Refine both
the front and side roto splines by moving any points that have drifted away back
into position.
Now go to a frame in the middle of the shot, say frame 12. Again, reposition
points as needed.
Note: The idea is to refine the spline on as few keyframes as possible and instead
depend on the tracking to drive the interpolation of the point positions
between keyframes. The approach we describe here is 'divide and conquer',
where you continually insert keyframes halfway between two existing
keyframes until the spline is accurate enough between two keyframes for any
further refinement not to be necessary. Another approach is to start at the first
frame and skip, say 10 frames, forwards for each keyframe.
What’s the Überkey? Powerful. And Dangerous.
The Überkey is a powerful tool that allows you to offset the positions of control
points without destroying their keyframe data.
Use this tool with care, as it is not setting any keyframes per se, it is offsetting
any and all keyframe data on the points you move while it is on. Überkey will
save your life one day, but don't let it ruin your day. Use with care.
Überkey affects only those frames between the timeline's In and Out point. If
you wish to make adjustments to a particular range, set the In and Out points to
that range.
Translate, Rotate and Scale your Splines
You can translate, rotate and scale selected points as a
group by using the corresponding tools listed in the toolbar.
An overlay shows the delta change.
The center or anchor point of these
movements appears where you first
click your mouse. Keep in mind that
these three tools do not work in
conjunction with the Überkey
function.
Turning On and Off Points
You can turn on and off individual points in a spline.
When they are off, you can still see the points, they
can still be animated, but they are not contributing
mathematically to the spline. This allows you to have
a complex spline only when you need it, rather than
having to deal with superfluous points in parts of the
shot when they are not needed.
To turn off points, select the points
on the spline and hit Shift+Delete.
You will see the curve change
shapes, but the points will remain.
To turn a point back on, right-click
on it and select Point->Activate.
If the Autokey button is enabled, a
keyframe will be created when you
change a point’s active status.
Add Motion Blur
You can use the movement of the
individual spline points to determine
motion blur. Any movement in the spline,
whether through simple X/Y translation or
by shape deformation will cause motion
blur.


You can control the amount of blur by
changing the motion blur value in the Edge
Properties panel.
Changing the Matte Blend Mode
Although not necessary in this example, note
that you can change how mattes are blended
in the Layer Properties panel. You may make
each layer’s matte Add or Subtract and you
can also invert the matte.
Note that this can't be keyframed and that
these settings apply to the entire layer, not to
individual splines of the same layer.
Viewing your Mattes
In the View Controls, several options are offered for viewing your mattes. The
Matte drop down is has options to view all mattes, just the mattes you have
selected or no mattes.
Select the Matte button and you will see your rotoscoped object against a flat
background.
Changing the Background Color
You may wish to rotoscope against a
particular color. Select View -> Canvas
Color… and a color picker will allow
you to choose a particular background
color.
Colorize your Matte Overlay
When you have your Mattes turned on, you may
choose for the matte to be filled with a color instead
of cutting out the object, using Colorize.
You can adjust the opacity of the color fill by changing the blend
value to the right of the Colorize button.
The color used by Colorize is derived
from the Selected and Unselected
properties of the Overlay Colors
panel, which can be changed per
layer.
This is only a preview and will not
affect how your mattes are rendered
when exporting.
Preview Rendered Mattes
In the View Controls panel, you will find a drop-down menu for selecting the
clip to view.
This allows you to view the actual rendered mattes, which can be especially
useful when tweaking motion blur. The motion blur you normally see in your
canvas is an OpenGL preview and can differ slightly from the actual render.
If you’d like to see what the actual motion blur render looks like, switch to
viewing the layer whose matte you
wish to see.
Because you can choose specific
layers for export when you render,
a render pass is created for each
layer.
Switch the View Clip drop-down
back to your source clip to continue
working with that clip.
To actually render your matte for use in a composite, read the instructions in the
chapter on exporting mattes.


Switch back to your After Effects window and locate and select the item on the
time line that is the insert object. Paste the data to the selected layer. You can
do this by selecting the ‘paste’ option in the edit menu or by typing “commandv”
(Mac) or “ctrl-v” (Windows).
Using Tracks For Stabilizing In After Effects
You can use the tracking data created to stabilize a shot in After Effects. The
process is simple.
Track your footage as normal, then turn
on the Surface button and center the
surface box on the area you wish to use
as the stabilize center.
Export the tracking data in the After Effects Transform format. Switch to After
Effects, select the layer you wish to apply the stabilize data to and paste it to
that layer.
Now delete the Position key frames. You can skip this step if you first delete this
information from the saved text file before copying it to After Effects.
Select the Rotation channel and click Animation | Add Expression. In the
expression box enter the formula rotation*-1.
Select the scale channel and click Animation | Add Expression. In the expression
box enter the formula:
x = 10000/scale[0];
y = 10000/scale[1];
[ x, y ];
You should now have a stabilized image.

1. Introduction
Welcome to mocha, tracking and rotoscoping tools that make your tracking and rotoscoping work
much easier.
Our tools are based on our proprietary Planar Tracking technology, an awesome approach to 2D tracking
which will help you to generate accurate corner-pins and track and transform your roto splines
in a powerful way.
Please note: This manual covers all products in the mocha family. Export and interface features may
differ between mocha Pro and mocha AE. Legacy applications such as mokey and monet will have
significant interface difference to the current versions. Please refer to their offline manuals.

The Art of Tracking
Tracking and rotoscoping are part of almost any visual effects project. For 2D tracking, point trackers
are most commonly used, but to get good point tracks requires a mix of experience and luck. You often
have to “prime” a clip for optimum tracking using color correctors and other image manipulations.
If the point being tracked exits frame, you get into offset tracking, which presents its own set of
challenges. If it all fails, you are into hand tracking, which is time consuming and very hard to get
accurate.
Mocha is a 2D tracker that requires less experience and luck to be successful with, does not require
the image to be primed and is less likely to require a lot of tricks or hand tracking on difficult shots.