QUANTITATIVE MEASURES Using values from Tissot(see Box 5.A) on all conformal projections, beverywhere on the projection. When a b, the value of20 is0°.Hence there is no angular deformation at points on con- formal projections. Because the values of a and b vary from place to place, however, the product of ab will alsovary from place toplace. Consequently, all conformal transformations enlarge or reduce areas relative to one another. The product ab at various points provides an index of the degree of areal change.