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> extent of passing the mark through walls, build- ings, trees, and other features having discernible height. a. All raw orthophoto negatives shall have fine- grained quality, normal uniform density, and such tone and degree of contrast that photo- graphic detail of the original aerial negatives is preserved to the maximum extent possible. Raw orthophoto negatives shall also be free of objectionable scan lines, image discontinui- ties, double exposures, and out-of-focus images. Exact final scale negatives are desir- able, which can be obtained by direct sheet- sized scanning from the neat model or by mosaic splicing of the negatives. If the negatives are formatted by mosaicking, the splicing shall be minimized. Variance in tone and/or color contrast between mosaicked segments of an individual formatted orthophoto and between adjacent map sheets shall not be objectionable to the eye. b. Screened positives shall be produced on a 4 mil mylar base material or as specified by the contracting agency or its representative. c. Geographic orientation and appropriate nota- tions shall be made on the orthophoto maps to identify or name principal geographic and physical features. d. photographic Requirements. Prior to making the final mylar maps, the contractor shall prepare at least 3 sample screened positives from the negatives under this contract, showing the var- ious ranges of contrast and tone obtainable. The contracting agency or its representative will review and select a quality desired. '. O. Other. Any items or features not covered in these specifications and relevant to the CWCB receiving acceptable aerial surveys and mapping by photogram- metric methods shall be as stated in the "Aerial Surveys and Mapping by Photogrammetric Methods for Highways," prepared by the Photogrammetry for Highways Committee of the American Society of Photogrammetry, u. S. Department of Transportation, 1968. -6-