Pfederer records twenty-seven institutional examples of portolan charts and atlases by Placido Caloiro e Oliva. 

The chart extends from Ireland to the tip of the Red Sea, from the Canary Islands to the Black Sea, taking in the coastlines of France and Spain, the shore of Morocco, and a double chart of the Mediterranean coastline plus a portion of the Black Sea coast.

Stylistically Oliva’s chart adapts an honoured but obsolete navigation tool, the medieval portolan, to the fact of early-modern navigation. It shows the features of a traditional portolan, with ample space for medieval bestiary and typified representations of places, but also a chart that records the relative positions of land masses more accurately than the traditionally calculated angles. The main body of the chart is divided in two to show both the medieval and corrected views of the Mediterranean, enabling the owner to compare them directly. The corrected axis shows Crete and Cyprus aligned on the same parallel. 

Oliva produced a very similar chart to this one the next year, in Livorno. The two charts have the same essential layout but the decoration in the present example is considerably richer, linking it more closely to the medieval tradition. The similarity of the 1617 and 1618 portolans has led scholars to surmise that even though this example is signed by Placido Caloiro e Oliva, it may rather be the work of 

 and then embellished by his family after 

 (fl. 1570–1614), was a leading member of the Oliva family, a cartographic dynasty who dominated portolan chart production in Europe during the sixteenth and early seventeenth centuries. 

s signed by no fewer than sixteen different members of the Oliva family are recorded between 1538 and 1673, and individual members apparently worked throughout the Mediterranean world, as their charts originate from Mallorca, Messina, Naples, Livorno, Florence, Venice, Malta, Palermo, and Marseilles. The exact relationships between the various members are unclear, but Joan appears to have been one of the most prolific and highly regarded. The earliest of his charts were executed in Messina, but he is also recorded as living in Naples as well as Marseilles, where he is thought to have died.

Oliva’s sixteen-chart atlas tackled the problem of magnetic declination in reference to new observations from European exploration of the 

. Ever since Europeans arrived in the Americas, the phenomenon of magnetic declination had been observed empirically by sailors and it often implied very challenging departures from their earlier charts. By rotating the axis an average of nine degrees clockwise, Oliva was able to create more accurate calculations. His method became the generally accepted view at the time, in competition with the calculations of Bartolomeo Crescenzio and Gerolamo Costo.

A very unusual double portolan chart of the Mediterranean by the celebrated cartographer 

. Linking the medieval and modern, Oliva adapts an honoured but, by then, obsolete tool, the Medieval portolan, to the realities of early-modern navigation. His map shows the features of a traditional portolan, with ample space for medieval bestiary and typified representations of places, but also a chart which records the relative positions of land masses more accurately than the traditionally-calculated angles. 

A very unusual double portolan chart of the Mediterranean, linking the medieval and modern, with a committed attempt to adapt an honoured but, by then, obsolete tool, the medieval portolan, to the realities of early-modern navigation. It shows the features of a traditional portolan, with ample space for medieval bestiary and typified representations of places, but also a chart which records the relative positions of land masses more accurately than the traditionally-calculated angles (Wilson). Richly decorated and particularly attractive.

Illuminated manuscript double portolan chart, pen and ink and colour wash, heightened in gold and silver, on vellum; coastlines drawn in brown ink extending west to east from the Azores to the Holy Land, and north to south from the British Isles to the north coast of Africa, from western Sahara to the Red Sea, islands in green and yellow, rivers in blue, numerous coastal place-names in red and sepia in semi-italic lettering, 30 city views, including duplicates, with flags, 8 full and 2 half compass roses, all with fleur-de-lys north points, two large elaborate scale cartouches, decorated with sea monsters, sailing ships, galley ships, several land animals (lion, camel, unicorn, deer), palm trees, rhumb lines in green, red, and brown; the whole in a foliate border of red, blue and brown entwined acanthus leaves.

Oliva's 'Doppia' Portolan Chart of the Mediterranean