1. A method for influencing a depiction of a three-dimensional object that is displayed using volume rendering, the method comprising: providing a representation of the object, in which values of a variable characterizing the object are given at spatial points of the object in a form of gray scale values obtained through imaging of the object, and in which color values are allocated to the variable during the course of the volume rendering; inputting a set of points defined in a space of the representation of the object; calculating a distance from the spatial points in the space of the representation of the object to the set of points, wherein a first segment that connects a first spatial point and the set of points is not restricted to being parallel to a second segment that connects a second spatial point and the set of points, wherein the calculated distance is either along the first segment or the second segment; inputting a threshold value for comparison with the calculated distance; modifying the color values allocated to the spatial points according to the calculated distance from the set of points when the calculated distance is smaller than the threshold value; and calculating a depiction of the object by the volume rendering, using the representation of the object, wherein the representation comprises the modified color values.