Synthetic data is data generated by models or my manipulating real data. It can be useful for training deep neural networks when there is insufficient real data or real data is hard to obtain. For example, 3D simulations can be used to emulate near accident situations, such as pedestraians crossing buy roads or in the dark; these will hopefully be rare in real gatgered video data, but invaluable to help autonomous cars respond well to exerme events. Synthetic data can also help generalisation, for example by adding noise to images or addings cropped, rotated or resized copies. Synthetic data has also be sggestd as a way to reduce bias in data sets.
Used on page 154