Huge quantities of art were produced for use in both public venues and for the home
The human figure was the main motif in Roman art:
The portrayal of the human figure was codified and stylized:
Ordinary (mortal/real) humans (men, women, and children) are *NORMALLY* depicted fully clothed
Empresses and high ranking wives, when not depicted in the guise of a goddess, are almost always in some version of the "good wife" outfit of tunica, stola, and palla and/or the modesty pose to reinforce their image as a "good wife of high reputation". This remains true even after the "good wife" outfit is no longer in fashion.
Gods, goddesses, and heroes are *usually* depicted naked, partially clothed, and/or with their nipples showing, with diadems/crowns and holding symbols of their power(s)
The portrayal of real humans in the guise of gods/goddesses varied -
Empresses were frequently depicted "as" goddesses, especially if they were deified after their death. They were normally depicted: fully clothed in the traditional "good wife" outfit, but with their nipples showing through the fabric of their clothing; wearing the contemporary hairstyle they were known for; wearing the diadem and other jewelry of the goddess; and holding the symbol of the goddess being depicted.
Emperors were more likely to be depicted partially clothed when in the guise of a god as there was no stigma attached to it
There was a fashion in the Antonine period (138-193 CE) for non-Imperial couples to have themselves depicted as gods and goddesses, especially Venus & Mars
Gods, goddesses, and heroes tend to be depicted in specific garments and/or accessories based on their Greek prototypes
These garments are often stylized versions of "archaic" dress, sometimes blended with elements of contemporary fashion (similarly to how fairy tale books today depict the characters in "archaic" but historically inaccurate clothing, and how biblical scenes are depicted)
The symbolic clothing of gods/goddesses includes:
naked or half-dressed men, and women who are naked, half-dressed, or have displayed nipples
women wearing a skimpy "tube dress" (likely the archaic vestis longa)
women with their dress falling off one shoulder, possibly with one breast exposed
Mars & Venus = a man naked, but wearing a helmet and/or carrying a weapon, and a woman totally or partially naked
holding symbols associated with specific gods or goddesses in their hands (for example: Neptune's trident, Juno's diadem & pomegranate, Minerva's owl, Apollo's bow & arrows, Ceres' cornucopia, etc.)
wearing a crown or diadem - in general, only women of the Imperial family and goddesses wore diadems.
In this case a diadem refers to a "tiara-shaped" or "crown-shaped" crown or coronet which stands up from the surface of the head. Other Roman women are depicted wearing cloth and/or metal plain or decorated bands which lie flat on the head.
In the late 3rd century CE there was a movement to depict gods and goddesses in less archaic dress, but they are still not wearing real, contemporary dress either (think of the depictions of Saints during the Renaissance)
The primary aim of Roman artists was *not* to render accurate, detailed representations of current clothing styles (unfortunately)
Roman artists had a deep reverence for ancient Greek art, and made many copies of Greek-era statues
Roman artists used a catalogue of stylistic conventions that conveyed important messages about the people represented in the art to their audience
Much of the extant Roman-era art that is readily available to us today is either unlabeled, partially labeled, mislabeled, and inaccurately dated, and/or not dated at all
Other common issues encountered by amateur researchers:
No back or side views available of many sculptures
"Artistic" camera angles
Non-Roman works in the Roman style (often unlabled) are often mistaken for Roman art by amateurs