Rotation

Rotation is an operation used to change the position angle of an image.

Based on a set of input images (or, if this is not the first operation, previously generated data), it iteratively creates a series of new images. In each iteration, the input image is rotated by a multiple of the Angle specified in the parameter. The loop ends when the rotation reaches 360 degrees, or when the limit of images per rotation specified in the Generate up to parameter is reached.

For example, for an Angle of 30 degrees, 12 new photos rotated by angles of 30°, 60°, 90°, 120°, 150°, 180°, 210°, 240°, 270°, 300°, 330° and 360° will be generated.

A maximum of 35 images can be created from a single photo. Blank spaces are replaced by a black area in JPG format or by transparency in PNG format.

The rotation operation may cause some part of the annotated object to fall outside the image, i.e. to be cropped. The Crop threshold function determines how much of the object must be visible in the resulting image for the annotation to make sense. Setting the crop threshold will cause annotations of objects with visibility less than the indicated percentage to be removed.

The Rotation option can only be used once. Using it multiple times would result in a very large number of very similar images, without increasing the effectiveness of the models trained on them.