Air Fronts: FM 21-26, Advanced Map and Aerial Photograph Reading - Section 11.

SECTION XI:  PHOTOMAPS

72. TYPES OF PHOTOMAPS. A photomap is a reproduction of a photograph or mosaic on which grid lines, marginal data, and place names are added (fig. 78). While a photomap usually is a reproduction of a mosaic, either controlled or uncontrolled, it may be the reproduction of a single photograph of any type. Vertical photographs are usually reproduced with a point-designation grid (see par. 69). A photomap made from an uncontrolled mosaic gives a good picture of the terrain and can be prepared quickly, although it will have errors in scale and direction. A photomap made from a controlled mosaic takes much longer to prepare, but can be scaled accurately.

73. MARGINAL DATA. Marginal data for the reproduced individual photograph are given in paragraph 59, with the addition of the point-designation grid system. Photomaps which are made from mosaics and widecoverage photographs may have, in addition, the following information:

a. Marginal information similar to that shown on maps, such as graphic scale, declination diagram, date made, and locality.

b. Name of towns, streams, mountains, highways, and other important features.

74. MILITARY GRID. While the military grid is not used on single photographs or on uncontrolled mosaics, it is highly desirable on controlled mosaics and photo

Figure 78. A photomap.

maps. The military grid is used in the same manner as with a topographic map (see par. 27). The method of placing a military grid on a mosaic is shown in TM5-230.