Riemannian metric tensors are used to control the adaptation of meshes for finite element and finite volume computations. To study the numerous metric construction and manipulation techniques, a new method has been developed to visualize two-dimensional metrics without interference from any adaptation algorithm. This method traces a network of orthogonal tensor lines to form a pseudo-mesh visually close to a perfectly adapted mesh but without many of its constraints. Although the treatment of isotropic metrics could be improved, both analytical and solution-based metrics show the effectiveness and usefulness of the present method. Possible applications to adaptive quadrilateral and hexahedral mesh generation are also discussed.