1. A method for determining a virtual target path which is used to calculate an evasive steering path for a subject vehicle around a target object in a travel path of the subject vehicle without using lane markings, said method comprising: a collision avoidance system programmed for: providing a plurality of scan points identifying detected objects from one or more sensors on the subject vehicle; separating the plurality of scan points into target object scan points received from the target object and other object scan points received from other objects; determining a potential field using the plurality of scan points that is a summation of two-dimensional Gaussian functions, where each Gaussian function has a center defined by the target object scan points and the other object scan points; identifying a mesh grid in an X-Y plane and in a predefined region where the steering path will be located where the mesh grid includes mesh grid points at locations where X and Y plane lines cross, and where X plane lines are in a direction of the travel path of the subject vehicle and Y plane lines are in a perpendicular direction to the X direction; identifying a potential field value from the potential field at each mesh grid point; identifying a local minimum point of the potential field for each X plane line at each mesh grid point along a Y plane line crosses that X plane line, where the local minimum point is a curve point and where each X plane line includes a curve point; calculating a corridor width between the target object and other objects and using the corridor width as a weight coefficient to determine an optimal virtual target path such that a path with a wider corridor width is preferred over a path with a narrow corridor width; and connecting the curve points to define the virtual target path.