Announcing Auto-Segmentation Tracking For Video

Akruti Acharya
March 22, 2024
5 min read
blog image

In computer vision, where accurate training data is the lifeblood of successful models, video annotation plays an important role. However, annotating each frame individually is time-consuming and prone to inconsistencies. Nearby frames often exhibit visual similarities, and annotations made on one frame can be extrapolated to others. Enter automated polygon and bitmask tracking!

Automated segmentation tracking significantly reduces annotation time, while simultaneously improving accuracy - gone are the days of tediously labeling every frame in a video. Polygon and Bitmask tracking provides the tooling required to build labeled training data at scale and at speed.

Polygon tracking meticulously outlines objects with a series of interconnected vertices, offering precision and flexibility unparalleled in video annotation. Conversely, Bitmask tracking simplifies the annotation process by representing object masks as binary images, streamlining efficiency without compromising clarity.

Join us as we explore these techniques that are not just enhancing the process of video annotation, but also paving the way for more accurate and efficient machine learning models. 🚀

Training CTA Asset
<Curate your Video Dataset with Encord >
Book a live demo

Understanding Polygon and Bitmask Tracking

Polygon Tracking

A polygon is a geometric shape defined by a closed loop of straight-line segments. It can have three or more sides, forming a boundary around an area. In video annotation, polygons are used to outline objects of interest within frames. By connecting a series of vertices, we create a polygon that encapsulates the object’s shape.

Advantages of Polygon-Based Tracking

  • Accurate Boundary Representation: Polygons provide a precise representation of an object’s boundary. Unlike bounding boxes (which are rectangular and may not align perfectly with irregular shapes), polygons can closely follow the contours of complex objects.
  • Flexibility: Polygons are versatile. They can adapt to various object shapes, including non-rectangular ones. Whether you’re tracking a car, a person, or an animal, polygons allow for flexibility in annotation.

Use Cases of Polygon Tracking

  • Object Segmentation: When segmenting objects from the background, polygons excel. For instance, in medical imaging, they help delineate tumors or organs.
  • Motion Analysis: Tracking moving objects often involves polygon-based annotation. Analyzing the trajectory of a soccer ball during a match or monitoring pedestrian movement in surveillance videos are examples.

Bitmask Tracking

A bitmask is a binary image where each pixel corresponds to a specific object label. Instead of outlining the object’s boundary, bitmasks assign a unique value (usually an integer) to each pixel within the object region. These values act as identifiers, allowing pixel-level annotation.

Advantages of Bitmask-Based Tracking

Bitmasks enable precise delineation at the pixel level. By assigning values to individual pixels, we achieve accurate object boundaries. This is especially useful when dealing with intricate shapes or fine details.

Use Cases of Bitmask Tracking

  • Semantic Segmentation: In semantic segmentation tasks, where the goal is to classify each pixel into predefined classes (e.g., road, sky, trees), bitmasks play a vital role. They provide ground truth labels for training deep learning models.
  • Instance Segmentation: For scenarios where multiple instances of the same object class appear in a frame (e.g., identifying individual cars in a traffic scene), bitmask tracking ensures each instance is uniquely labeled.

Temporal Consistency

Maintaining temporal consistency when annotating objects in a video is crucial. This means that the annotations for an object should be consistent from one frame to the next. Inconsistent annotations can lead to inaccurate results when the annotated data is used for training machine learning models.

Temporal smoothing and interpolation techniques can be used to improve the consistency of the tracking. Temporal smoothing involves averaging the annotations over several frames to reduce the impact of any sudden changes. Interpolation, on the other hand, involves estimating the annotations for missing frames based on the annotations of surrounding frames. Both these techniques can greatly improve the quality and consistency

light-callout-cta Read the documentation, to know how to use interpolation in your annotation.

Applications of Polygon and Bitmask Tracking

Polygon tracking in video annotation

Object Detection and Tracking

With polygon tracking, objects of any shape can be accurately annotated, making it particularly useful for tracking objects that have irregular shapes or change shape over time. Bitmask tracking takes this a step further by marking each individual pixel, capturing even the smallest details of the object. This level of precision is crucial for detecting and tracking objects accurately within a video.

Semantic Segmentation

In semantic segmentation, the goal is to classify each pixel in the image to a particular class, making it a highly detailed task.

Bitmask tracking, with its ability to mark each individual pixel, is perfectly suited for this task. It allows for the creation of highly accurate masks that can be used to train models for semantic segmentation. Polygon tracking can also be used for semantic segmentation, especially in scenarios where the objects being segmented have clear, defined boundaries.

Interactive Video Editing

Interactive video editing is a process where users can manipulate and modify video content. This involves tasks such as object removal, color grading, and adding special effects.

Polygon and bitmask tracking can greatly enhance the process of interactive video editing. With these techniques, objects within the video can be accurately tracked and annotated, making it easier to apply edits consistently across multiple frames. This can lead to more seamless and high-quality edits, improving the overall video editing process.

Semantic Context and Automation

Semantic Context

  • Scene Understanding: When placing polygons or bitmasks for video annotation, it’s crucial to consider the context of the scene. The semantics of the scene can guide accurate annotations. For instance, understanding the environment, the objects present, and their spatial relationships can help in placing more accurate and meaningful annotations.
  • Object Relationships: The way objects interact within a scene significantly affects annotation choices. Interactions such as occlusion (where one object partially or fully hides another) and containment (where one object is inside another) need to be considered. Understanding these relationships can lead to more accurate and contextually relevant annotations.

Automated Annotation Tool

  • AI Assitance: With the advancement of machine learning models, we now have the capability to propose initial annotations automatically. These AI tools can significantly reduce the manual effort required in the annotation process. They can quickly analyze a video frame and suggest potential annotations based on learned patterns and features.

  • Human Refinement: While AI tools can propose initial annotations, human annotators are still needed to refine these automated results for precision. Annotators can correct any inaccuracies and add nuances that the AI might have missed. This combination of AI assistance and human refinement leads to a more efficient and accurate video annotation process.

light-callout-cta Read the blog The Full Guide to Automated Data Annotation for more information.

Real-World Applications

Polygon and Bitmask tracking, along with the concepts of semantic context and automation, have a wide range of real-world applications. Here are a few key areas where they are making a significant impact:

  • Medical Imaging: In medical imaging, precise annotation can mean the difference between a correct and incorrect diagnosis. These techniques allow for highly accurate segmentation of medical images, which can aid in identifying and diagnosing a wide range of medical conditions.
  • Autonomous Vehicles: Polygon and Bitmask tracking allow these vehicles to understand their environment in great detail, helping them make better driving decisions.
  • Video Surveillance: In video surveillance, tracking objects accurately over time is key to identifying potential security threats. These techniques can improve the accuracy and efficiency of video surveillance systems, making our environments safer.

These are just a few examples of the many possible applications of Polygon and Bitmask tracking. As these techniques continue to evolve, they are set to revolutionize numerous industries and fields.

In summary, Polygon and Bitmask tracking are transforming video annotation, paving the way for more precise machine learning models. As we continue to innovate in this space, we’re excited to announce that Encord will be releasing new features soon. Stay tuned for these updates and join us in exploring the future of computer vision with Encord. 🚀

Written by Akruti Acharya
Akruti is a data scientist and technical content writer with a M.Sc. in Machine Learning & Artificial Intelligence from the University of Birmingham. She enjoys exploring new things and applying her technical and analytical skills to solve challenging problems and sharing her knowledge and... see more
View more posts
cta banner

Build better ML models with Encord

Get started today
cta banner

Discuss this blog on Slack

Join the Encord Developers community to discuss the latest in computer vision, machine learning, and data-centric AI

Join the community

Software To Help You Turn Your Data Into AI

Forget fragmented workflows, annotation tools, and Notebooks for building AI applications. Encord Data Engine accelerates every step of taking your model into production.