Tactile maps and diagrams are raised line pictures used to present graphical information to people with visual impairments, corollary to Braille being used to present textual information. It has been demonstrated that inkjet technology offers a novel and potentially highly efficient means of producing tactile maps.The technology utilized a custom-built flatbed printer with a 180 dpi 500 nozzle print head and ultra violet curing inks. By only partially curing print layers, sufficient that ink drops on the substrate remained domed, subsequent layers were printed which would cross-link and form a homogenous material protruding from the surface of the substrate. The 180 dpi print resolution inherent of a commercial print head is more than sufficient to exceed the areal tactual acuity of the most sensitive user. The ability to build three-dimensional features onto substrates at resolutions of 180dpi or less means more distinct symbol, line and texture features can be manufactured than by any standard tactile map making method.Psychophysical studies have revealed that users are able to understand far lower print heights than the previously recommended half a millimeter and there is a preference for matt substrates. Further research will continue to combine materials science and systems engineering principles with those of psychology and cartographic design to fully exploit the technology in such a way that it is of most benefit to the end user.
Don McCallum, Jonathan Rowell, Simon Ungar, "The Use of Ink-jet to Produce Tactile Maps" in Proc. IS&T Int'l Conf. on Digital Printing Technologies (NIP19), 2003, pp 891 - 896, https://doi.org/10.2352/ISSN.2169-4451.2003.19.1.art00105_2