Overview of the Polygon labeling tool in Ango Hub

The polygon labeling tool allows you to draw a polygon around an object or point of interest in an image.

How to add a Polygon tool to your project

From the project’s Settings tab, enter the Label Set section.

Click on Add Category. From the list that appears, click on Polygon.

A new row will appear named Polygon. Click on it to expand it.

Give your polygon tool a title and description.

Enable the Required toggle if you want to force labelers to create a polygon on every asset. When the toggle is disabled, labelers will be able to save and move to the next asset without creating a polygon.

If you would like to ask labelers further questions, for example, if you want to show a further radio after drawing the polygon, click on Add Classification and add a further question. More on nested questions here.

How to Draw a Polygon

Click on the image where you’d like the first point of the polygon to be. Click again where you’d like the second point to be, and so on. When you are done, click on the first point again or press on N on your keyboard to close the polygon.

While drawing, you may click anywhere with the right mouse button to delete the last point you have placed.

To add a new point after closing the polygon, hold CTRL and click anywhere on an edge to add a point. To delete a point, hold CTRL and right-click on the point you’d like to delete:

To quickly trace a polygon without having to click on each point manually, after having drawn the first point, hold Shift then start moving your cursor:

Edge Sharing

While drawing a polygon, if you press E, Hub will highlight the points of other polygons, polylines, and points. By clicking on the other object's points, you can snap your current polygon's points to them:

You can also share edges with the polygon itself the same way:

By snapping at least two points to the existing polygon and holding Alt (⌥ on macOS) + clicking, you can quickly anchor a series of points to the existing object:

Nudge Tool

You can apply small changes to your polygons by 'nudging' them.

To nudge a polygon, click on the polygon on the asset, then pick the type of nudge tool you'd like to use:

Nudge Erase will allow you to reduce the size of your polygon while applying small changes. Nudge Draw will add area to your polygon.

Once you have picked your nudging tool of choice by clicking on either the "plus" or the "minus", click and drag around the polygon's edge to refine the edge of your polygon:

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