A Lambert Conformal Conic (LCC) projection with two true-scale parallels of latitudes ϕ_l and ϕ_u can be recast in a LCC projection with one standard parallel of latitude ϕ₀ and scale k₀, having the practical advantage that the same type of definition can be used for the two conformal projections universally used: LCC and Transverse Mercator (TM). While equations giving ϕ₀ and k₀ in terms ϕ_l and ϕ_u can be found in the literature, inverse relationships are not readily found. They are derived in the present paper. These may be necessary in views of the planned future definition of the United States State Plane Coordinate System (SPCS) 2022 for the users of particular mapping software requiring to specify the two latitude values instead of the central latitude and central scale. While map projection parameters are customary selected to minimise ellipsoid-to-grid distortions for a region, in some cases it could be more convenient to study and minimise ground-to-grid distortions. Also bearing in mind the design of SPCS 2022, we discuss the advantages and disadvantages of working with each type of distortion definition.

具有两个纬度ϕ _l和ϕ _{u 的}真实尺度平行线的兰伯特等角圆锥 (LCC) 投影可以在具有纬度ϕ ₀和尺度k _{0 的}一个标准纬线的 LCC 投影中重铸，具有以下实际优势：定义可用于普遍使用的两种共形投影：LCC 和横轴墨卡托 (TM)。而方程给出ϕ ₀和k ₀在ϕ _l和ϕ _{u 方面}可以在文献中找到，逆关系不容易找到。它们是在本文中导出的。考虑到美国国家平面坐标系 (SPCS) 2022 的计划未来定义，对于需要指定两个纬度值而不是中央纬度和中央比例尺的特定地图软件的用户，这些可能是必要的。虽然习惯上选择地图投影参数来最小化一个区域的椭球到网格失真，但在某些情况下，研究和最小化地面到网格失真可能更方便。同时考虑到 SPCS 2022 的设计，我们讨论了使用每种失真定义的优缺点。