The aerial photography shall be taken at such time as deciduous trees are free of leaves and the ground is free of seasonal snow. The aerial photography shall be produced in a controlled manner under specifications sufficient to meet the accuracy requirements of the base manuscripts.

Control points utilized in the photogrammetric procedures in the preparation of the base manuscripts shall consist of existing monumented stations established by or for the United States governmental agency now known as the National Geodetic Survey, and additional points established by ground surveys and/or aerial triangulation. Ground surveys shall be based upon said existing monuments using generally accepted procedures and achieving results consistent with the accuracy requirements for the base manuscripts. Aerial triangulation shall be based upon said existing monuments and said ground surveys and shall also be executed using generally accepted procedures and achieving results consistent with the accuracy requirements of the base manuscripts.

Base manuscripts shall be prepared by photogrammetric methods using stereo plotting instruments and aerial photographs obtained with cartographic cameras. The New York State plane coordinate system shall be adopted as the horizontal datum for all base manuscripts; grid intersections shall be shown at intervals of five inches and shall not vary by more than 0.01 inch from true grid value on each map sheet. Each horizontal control point shall also be plotted on the map sheets within the coordinate grid and should lie to an accuracy of 0.01 inch of its true position as expressed by the plane coordinates of the point. Manuscripts shall be compiled directly to the required map scales with the exception of the one inch equals 50-foot scale. One inch equals 50-foot manuscripts may be obtained by photographic enlargement of one inch equals 100-foot manuscripts. The absolute horizontal accuracy of the manuscripts shall be such that 90 percent of all well defined planimetric features shall be plotted within one fortieth of an inch of their true coordinate position as measured on original one inch equals 400-foot and one inch equals 200-foot manuscripts. For one inch equals 100-foot manuscripts the requirement shall be one twentieth of an inch. Well defined features within each original manuscript shall be of greater relative accuracy than of absolute accuracy. Use of the term absolute in this subdivision shall be construed as being in relation to the nearest National Geodetic Survey stations used for ground surveys and/or in aerial triangulation.