1. A method for computing a change in an image scale of an object, comprising: recognizing image coordinates of characteristic image areas in an instantaneous image, the characteristic image areas depicting object features at least of the one object in the instantaneous image; providing a model, wherein model coordinates of the model represent a selection of positions of recognized object features of the object in a preceding image; scaling the model in order to obtain a scaled model, at least a portion of the model coordinates being correlated with the image coordinates recognized in the step of recognizing, and the model and the scaled model differing from one another by a model scaling factor; ascertaining an image scaling factor using the image coordinates of at least two recognized characteristic image areas, and image coordinates of the two image areas recognized in the preceding image; and combining the model scaling factor with the image scaling factor in order to obtain the change in the image scale.