地圖係由各種符號所組成，而符號與實體地物間存在著幾何對應之關係。在地圖資料蒐集過程中，即為對地物進行抽樣作為，比例尺愈大則抽樣程度愈高，在單位面積內所投入之製圖作業經費亦愈高。本文旨在探討基本地圖之定義與內涵，及在制定國家基本地圖系列時比例尺因素對其之影響，以為未來國家地圖發展之參考。

Maps are composed of symbols, the geographic features that were mapped will hold the geometric correlation with those symbols. In the process of map production, map data gathering means to sampling from these features. The density and frequency of data sampling will went higher when the map scale became more larger, and the spend of mapping will increasing quickly. The theme of this article is to discuss the definition and essence of the base map. Besides, the influences of scale factor in the constituting of national base map series were also be considered. It is helpful in the development of national mapping.