This article analyzes the principles of compilation and source utilization in Wisa, a late eighteenth-century world geography treatise that sought to integrate the Xiantian (先天, Prior Heaven) cosmological framework with mathematical astronomy derived from the Zhoubi (周髀). Conceived by Seo Myeong-eung (徐命膺) and completed by Seo Yu-gu (徐有榘), Wisa grounded geographical knowledge in celestial order, expressed through latitude. Its core lies in a latitudinal system of regional classification, implemented through analytical categories such as Geug-wi (極緯, Polar Altitudes, quantifying latitude) and Hwangjeok-gyeong (黃赤經, Solar Altitudes, calculating seasonal day/night length). Drawing on Western cartographic and geographical sources, including Matteo Ricci’s Kunyu Wanguo Quantu (坤輿萬國全圖), as well as Chinese classical texts, the compilers collated and recalibrated geographical data. This synthesis of Western astronomical knowledge with the indigenous Xiantian system reveals both the intellectual ambitions and methodological constraints of the project, ultimately reconfiguring geographical description within an astronomical and calendrical order aimed at interpreting the Yugong (禹貢).