3a. Setup: Object Marking

Table of Contents

What is Object Marking?

By marking the objects you wish to track on certain frames of your video, ABC Tracker is able to determine the size, visual appearance, quantity, and environment of objects to be tracked. Please mark objects carefully: these marks are used extensively throughout the tracking process.

Sample of Fully Marked Frame

How Many Frames Will be Marked?

Currently, ABC Tracker usually requests object markings on three frames.

 Occasionally, ABC Tracker will request more than three frames...

ABC Tracker would like to have at least 50 object marks before running tracking. This allows the tracker to have a sufficient amount of data about the visual appearance and size of the objects to be tracked.

If the source video has fewer than 15 objects in each frame, ABC Tracker may request object marking on more than three frames.

How to Mark Objects

Set the Correct Brush Size

Set the brush size to cover the body of the objects, but as little image background as possible.

The brush size can be set using either:

  • The scroll wheel on a mouse, or
  • The "Brush Size" slider underneath the playback video


It is important to cover just the body of the objects, and not a large amount of the background image. To do this, it may be necessary to use the zoom features.

Mark Each Object

Mark the objects by clicking three times on each object: once on the object's head, once in the center of the object, and once on the object's tail.

While it does not matter whether the head or tail are selected first, the center of the object will need to be the second click.

How to Undo Object Marks

Undoing an Incomplete Mark

If a mark has not yet been completed (i.e. there are only 1 or 2 highlighted circles, and the third click has not been completed), right clicking with the mouse anywhere on the video area will remove the incomplete mark.

Undoing a Completed Mark

If a mark has been completed, right clicking with the mouse on the finished mark will remove only that single mark.

Questions on Object Marking

What if No Objects Exist in Frame?

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If no objects exist in a frame, select the "No Objects Present" button

What if Object has an Abnormal Appearance in Frame?

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Sometimes an object takes on an unusual appearance in a particular frame being marked, such as the object not marked here:

In these cases, it is still important to mark the object, approximating the head, middle, and tail of the object as well as possible.

Since ABC Tracker will later examine the video footage and track the object's appearance before and/or after the selected frame, the application will compensate for the object's unusual appearance in that specific frame.

The completed markings for the object above look like this:

What if Object is Partially Off of Screen?

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In general, if more than half of the object is visible in the frame being marked, then the entire object should be marked.

What if Part of the Image should be Ignored (Binary Mask)

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ABC Tracker has the ability to ignore certain regions of a video. This is useful if, for example, only objects outside of a colony should be tracked, or vice-versa.

To learn how to do this, see Video Processing: Use Binary Mask.

Read Next: Define Tracking Area