One approach to overcome this would be to use a long, thin cylindrical brush. The problem with this approach is that painting a fine line with such a long, thin brush would force us to ensure that the brush is perpendicular to the mesh throughout the stroke. Slight changes in brush orientation would change the size of the area painted on the mesh.
An alternative approach is to give the user the option of ``gluing'' the brush to the mesh. When painting, the location of the brush is constrained to be the closest point on the mesh to the sensor, rather than the sensor's location itself. We can think of this as extending the tip of the brush so that it always touches the mesh surface. Since the brush's position is now forced to lie on the surface, we can paint with very small brush shapes, even in the presence of registration errors.