There are several problems. One is that haptic perception is much less detailed than visual perception. Another is that most blind people have little experience in reading tactile pictures. Consequently it is difficult to make tactile pictures that are very detailed without simultaneously making them confusing to blind readers. Research on haptic perception, development of inexpensive methods for making tactile graphic materials, and early training of blind children in techniques for reading tactile graphics are needed before the full potential of tactile graphic materials is likely to be realized.
Reference is made to a few other research efforts as well.