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Polygon Annotation

When it’s time to annotate your data, the Workspace is where the magic happens. The Workspace is a feature-rich interface for creating polygons, or multi-sided irregular shapes, that are tightly constrained to the edges of an object that you wish to label with a class.

Tagging Tools

Brain Builder includes a number of tools in the Workspace to make your tagging more efficient—each of which may be best suited to tag different types of objects. Tools may be selected with a mouse click or with hotkeys (noted in parentheses).

Drawing Tools

Brain Builder features a suite of drawing tools that allow you to create and refine polygons.

  Pen Tool (P)

Use the Pen tool to create sequential anchor points around the object. The Pen tool works best with objects that have straight-lined edges. To complete the polygon, make your way back to the first anchor point and click it.

  Brush Tool (B)

Hold down the Brush tool to create a polygon that follows the contours of the path drawn by the pointer. Works best when tagging irregular objects that lack straight lines. The polygon completes itself when you release the click. Works best with a mouse or tablet/stylus for control.

  Addition Tool (A)

The Addition Tool increases the area of an existing polygon. Use this tool to draw a polygon that at least partially overlaps the polygon you want to add it to. When it is complete, it automatically merges with that polygon.

The Addition Tool is a great choice for fine-tuning polygons created with Smart Fill, Snap-to-Fit, or AI Video Annotation.

  Subtraction Tool (D)

Use the Subtraction Tool to remove part of an existing polygon. With this tool selected, draw over the polygon to remove the area you create.

Cut Tool

The Cut tools are used to create a polygon without overlapping an existing polygon. It has two options:

Subtract from Background (G)

When you use this Cut tool, your new polygon erases any other polygons with which it overlaps and fills in the entire polygon as this class.

Subtract from Foreground (F)

When you use this Cut tool, you may overlap existing polygons but they persist and any areas of overlap are removed from the new polygon you create.

Smart Fill (S)

Use the Smart Fill tool to create polygons based on regions with similar color ranges. This tool works best when tagging objects that are mostly the same color (or within a narrow range) and have a distinct color from the area around them.

  1. Select the tool. You are prompted to select an area of the image. You can draw a rectangle to specify the region of the image where Smart Fill is applied, or click Next to select the entire image.

  2. Choose the color you want to focus on. The color selection tool helps you zoom in to the pixel-level detail of the image to select the color.

  3. Adjust the slider and see in real-time how the Smart Fill selection changes from low to high. Pick the level that best captures the objects you wish to label and click Accept.

  4. Choose the appropriate class from the Class selector.

Eraser (E)

Use the Eraser to decrease the area of a polygon by removing anchor points. This tool does not allow the same precision as the Subtraction Tool.

Other Workspace Tools

The Workspace has additional features to aid in accurate, efficient tagging.

Brightness (R)

Use the Brightness slider to change the brightness of the image. This can help reveal details to make tagging easier. It does not change the actual image.

Undo (Ctrl + Z Windows, Cmd + Z Mac)

Redo (Ctrl + Shift + Z Windows, Cmd + Shift + Z Mac)

Use Undo and Redo to step your tagging work back and forth to quickly correct mistakes.

Select Tool (T)

Use the Select tool to adjust anchor points, move polygons, or select polygons.

Move Tool (M)

Use the Move Tool to move the image within the screen. You can use the tool when you have zoomed in on the image.

Zoom ( + / - )

Use the Zoom tools to enlarge areas of the image for detailed tagging. You can zoom in, zoom, out, or type a specific zoom level into the text field.

Tagging Images

  1. Use the Pen Tool to draw a polygon around the object in the image that you want to label with a class.

    After a polygon has been created, the Class Selector appears.

  2. Assign a class to the polygon by choosing an existing class or creating a new one.


    When you have more classes than can be displayed at once in the Class Selector, typing a partial name will filter the selector to only show the matching classes.

    The Workspace also features a Class Manager where you can create, review, and edit your classes. See the Class Manager section below.

  3. When you’re finished drawing and tagging polygons on the image, click the Next > arrow in the top-right corner of the screen to move onto the next image. Your polygons save automatically.

Class Manager

Within the workspace, you can create, delete, and manage the Classes of objects you are annotating.

Open the Class Manager by clicking the Classes button at the top of the left-side toolbar. This opens a window where the current classes are listed with a count of the number of polygons that have been labeled with each class in the current Dataset. Within this window, you can:

  • Rename an existing class—Click the Class name and edit it as you wish.
  • Change the Class color—Click the color field next to the Class name and select a new color from the color selection window.
  • Delete a class—This will delete all associate polygons!
  • Add a new class—Type the name into the field at the top of the window.

Next: Polygon Annotation on Video >>