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When a rectangle would swallow half the background, you need a polygon. The Polygon tool traces an object point by point, which makes it the right choice for irregular shapes: billboards at an angle, vehicles in perspective, buildings, produce on a shelf, anything a box cannot hug.
Available in image projects. Polygons live in the same schema as your other annotations, so a class can mix boxes and polygons freely; the class color and hotkey work identically for both.

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Box or polygon?

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Draw a polygon

PixlHub editor with the class panel and Polygon tool highlighted with step markers

The two-step setup: arm the class with its hotkey, then pick the Polygon tool from the floating palette.

1

Arm the class

Press the class hotkey (shown as Hot: 1, 2, 3 in the class panel) or click the class name.
2

Select the Polygon tool

Click the polygon icon in the floating palette.
3

Click each vertex

Click along the object’s outline. Every click drops a vertex; the shape fills with the class color as it forms.
4

Close the shape

Double-click on the first vertex to close the polygon. It joins Object Instances with an ID like every other annotation.
Here is the full loop on a real scene, from tool selection to a closed polygon:

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Edit vertices

Select a polygon with the Select tool and its vertices become draggable handles. Pull any vertex to refine the outline; the polygon reshapes live.
Zoomed view of a Traffic Sign polygon with draggable vertex handles in PixlHub

A selected polygon exposes its vertex handles for fine-tuning.

As with every annotation, moving, reclassifying (press a different hotkey while selected) and deleting work the same way they do for boxes, and undo covers each vertex operation individually.

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Work precisely

  • Zoom first. Vertex accuracy is a function of zoom level; draw detailed sections at 200 percent or closer.
  • Fewer, better vertices. A clean 8-point outline usually trains better than a shaky 40-point one, and it is far easier to edit later.
  • Use the pixel readout. The status bar shows cursor coordinates, useful when guidelines specify snapping or margins.
  • Lock finished polygons. Dense scenes plus draggable vertices invite accidents; the lock toggle in Object Instances prevents them.

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Frequently asked questions

Select the polygon and drag existing vertices to reshape it. For a materially wrong outline, deleting and redrawing is usually faster than reworking many vertices.
Both export with their geometry type preserved, so downstream formats receive polygons as point lists and boxes as rectangles. See Exports for format specifics.
Yes, the Freeform tool draws continuous outlines instead of clicked vertices, and AI-assisted annotation can propose an outline you only correct. Polygon is the precision middle ground.

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Next steps

AI-assisted annotation

Let a model propose the outline; you adjust vertices instead of placing them.

Image annotation editor

The full editor tour: panels, palette, hotkeys, saving.