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<br />All the targets shall be located with GPS instruments, tied-in to local NGS control <br />monuments. Information of target locations will be utilized in the stereoscopic <br />photograph processing. <br /> <br />1 .1.1 Coordination <br /> <br />The Surveyors will meet and coordinate with the Photogrammetrist the <br />placement of the individual targets. These preliminary locations will be marked on <br />a map for field placement. Once the map is completed, the field crew will verify <br />that the preliminary target locations are suitable for the rectification process. If a <br />location is not suitable for target placement, then a new location will be chosen <br />and identified on the map. <br /> <br />, <br />Once the targets have been located and the coordinates accepted and approved <br />by the PLS, they will be forwarded to the Photogrammetrist to begin rectification <br />of the aerial data. <br /> <br />When the Photogrammetrist has completed his work, an ASCII file containing the <br />X, Y, 2, values for all points and a CADD file of line work will be provided to the <br />PLS for creation of the Digital Terrain Model (DTM). <br /> <br />1 . 1.2 Setting Target Locations <br /> <br />Once all target locations have been checked and approved, the field crew will <br />begin to place the individual targets. A P.K. nail and washer will be set at all <br />target centers placed on hard surfaces. <br /> <br />1.1.3 Placement of Targets <br /> <br />Once all target centers are placed, targets will be painted (a color contrasting <br />with the surface, usually white or black). All targets will be 4' x 4' crosses, unless <br />requested otherwise by the Photogrammetrist. <br /> <br />1.1.4 Target Locations and Coordinates <br /> <br />Targets will be located using Global Positioning Satellite (GPS) equipment <br />utilizing Rapid Static methods. Thorough reconnaissance and planning will be <br />used to insure precise, accurate results with a minimum of effort. At least 2 dual <br />frequency receivers will be placed on known control points with a published <br />accuracy of Second order Class I or greater. Each target will be observed on it's <br />center point twice, for at least 10 minutes with double occupations planned for <br />each point. The second occupation will utilize a different satellite configuration <br />and wherever possible, different control points from the first observation. <br /> <br />All vectors will be observed and processed, first through an unconstrained <br />adjustment, and then constrained to the original control points. This will be <br />