The History Of Cartography In Ancient China Explained

When Pei Xiu noticed that maps were not realistic enough during the Jin Dynasty, he decided to change them himself. He came up with six principles which were incorporated into future Chinese cartography. The Yu Gong Diyu Tu ("Tribute of Yu," that was yet another Yu the Great homage) was his compilation of maps, now mostly lost. However, according to historian Cordell D.K. Yee's book "History of Cartography," a piece of it copied into a later work survives.
Pei Xiu's six principles, as Yee lists them, are "proportional measure (fenlü), standard or regulated view (zhunwang), road measurement (daoli), leveling (or lowering) of heights (gaoxia), determination of diagonal distance (fangxie), and straightening of curves (yuzhi)." This was supposed to be an improvement on previous maps that were incomplete, and sometimes featured phantom landmarks. Fenlü was supposed to help readers make out the distance between things, zhunwang made sure locations were accurate, and daoli helped gave an idea of where exactly you were on the road. The rest — gaoxia, fangxie, and yuzhi — used geometry to get mountains and other aspects of the terrain correct.
Because of how he revamped cartography, Pei Xiu has been immortalized as "The Chinese Ptolemy," as Jerry Brotton says in his book "A History of the World in Twelve Maps."
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