Graphics of various types appear in documents of a (not only) scientific nature. It is not always appropriate, necessary or desirable to prepare them in a tactile form. In pedagogical practice we can thus encounter the following types (the boundaries between them are not always sharp).
The graphics have almost no information value. Their role is to make the content more attractive.
Their role is to make the content more comprehensible.
Schemes or other kind of graphics describing relations.
This graphic can exist independently, introducing new information that is not available elsewhere in this form.
The graphic does not carry any essential information, but is intended to generate discussion about the content.