Short answers, pulled from the story.
Lopo Homem was a 16th-century Portuguese cartographer and cosmographer born around 1497. Beginning in 1517, he served as the crown's official cartographer and Master of Nautical Instruments, holding exclusive rights to calibrating nautical compasses in Portugal. He is best known for his work on the Miller Atlas of 1519.
The Miller Atlas is a 1519 cartographic work consisting of eight maps across six sheets, painted on both sides. It is thought to be a joint work with Pedro Reinel, Jorge Reinel, and António de Holanda, commissioned by King Manuel I of Portugal as a state gift for Francis I of France. The atlas has been held by the National Library of France since 1897.
From 1517, Lopo Homem held exclusive royal rights to constructing and correcting nautical compasses in Portugal. Anyone else who calibrated a ship's compass was required to pay him 20 cruzados. King João III renewed these rights and the title of Master of Nautical Instruments in 1524.
In 1524, Lopo Homem served as an expert witness on behalf of the Portuguese crown at the Conferences of Badajoz-Elvas, which aimed to settle a dispute with Castile over rights to the Molucca Islands. He received a pension of 1,200 reais for this service, and a letter he wrote about the negotiations survives in the Torre do Tombo.
Lopo Homem's unnamed 1554 world map is identified as the first map in history to show Argentina. It built on ideas developed by the cartographer Sebastian Cabot and is currently held at the Museo Galileo in Florence, Italy.
Lopo Homem's known works, dated between 1557 and 1578, include eleven or twelve charts and twelve atlases. Seven of the atlases covered Europe and the Mediterranean Sea, and five were world atlases. His earliest surviving work is a world map discovered in London in 1930.