Annotation with rectangles

To learn more about annotation using a rectangle, see the sections:

• Shape mode (basics)
• Track mode (basics)

Annotation with rectangle by 4 points

It is an efficient method of bounding box annotation, proposed here. Before starting, you need to make sure that the drawing method by 4 points is selected.

Press Shape or Track for entering drawing mode. Click on four extreme points: the top, bottom, left- and right-most physical points on the object. Drawing will be automatically completed right after clicking the fourth point. Press Esc to cancel editing.

Rotated bounding boxes

You can draw a rotated box from contour points, rotate an existing rectangle, or change which side carries its white rotation marker.

Create a rotated box

Use the Rotated drawing method to create a bounding box around an object that is tilted in the image. Click points along the object’s outline, and CVAT calculates the smallest-area rectangle that encloses them, including its rotation angle. This method is available in both Shape and Track modes.

1. Open Draw new rectangle from the controls sidebar.
2. Choose a Label and select Rotated under Drawing method.
3. Click Shape or Track to start drawing.
4. Click at least three points along the object’s outline. Spread the points around the object to capture its full extent. The points must not all lie on a single straight line.
5. Check the box preview as you add points. Add more points where needed to capture the object’s outline.
6. Press N or click Done on the top panel to finish.

Unlike the 4 Points method, Rotated does not finish automatically after the fourth point. You can keep adding points before completing the box.

Action	Control
Add a contour point	Left-click
Remove the last contour point	Right-click
Finish the box	N or Done
Cancel drawing	Esc

The shortcuts above use the default key bindings.

Orientation marker

The white marker shows where the box’s rotation handle will be. It starts on the side closest to your first point. As you add points, the preview changes, so the marker may move to another side. It is not fixed to the first edge you draw.

To find the closest side, CVAT measures the perpendicular distance from your first point to the straight line that each side lies on. The marker is placed just outside the middle of the selected side. As the preview changes.

To help place the marker on the side you want, start near the middle of that side rather than at a corner. After drawing, you can move the marker to another side using Orientation in the object’s actions menu.

Rotate an existing box

Drag the white rotation handle to rotate a completed rectangle around its center. The rotation angle is displayed while you drag. Hold Shift to snap to multiples of 15 degrees. This works for rectangles created with any drawing method.

Change the box orientation

Use Orientation menu to move the white rotation marker to another side while keeping the box’s outline and covered image area unchanged. This is useful when the fitted box already matches the object, but the marker is on a different side than intended.

1. Open three-dot actions menu of the object and select Orientation.
2. Choose 90° with the clockwise arrow, 90° with the counterclockwise arrow, or 180°.