Eastern Topographics (e-topo.com)
Eastern Topographics - Aerial photography and topographic mapping of Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, Connecticut, New York and New Jersey.
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Mapping Standards

Provided minimum third order ground control (1:5000) is performed, map accuracy will be as follows:
Ninety percent (90%) of the elevations determined from the solid line contours of the topographic maps shall have an accuracy with respect to true elevation of ½ the contour interval or better, and no remaining contour line shall be in error by more than one full contour interval. In densely wooded areas where brush or trees substantially obscure the ground, contours will be shown as dashed lines, and be plotted as accurately as possible from the stereoscopic model. Areas of dense foliage will be identified as "ground obscured" and no contour lines will be shown. 

Spot Elevations:
Ninety percent (90%) of all spot elevations placed on the maps shall have an accuracy of at least ¼ the contour interval and the remaining ten percent (10%) no more than ½ the contour interval.

Coordinate Grid Lines:
The plotted position of each plan coordinate grid shall not vary by more than 1/100 of an inch (0.25mm) from the true grid value on each map manuscript. Horizontal Control: Each horizontal control point shall be plotted on the map manuscript within the coordinate grid in which it should lie to an accuracy of 1/50 of an inch (0.51mm) of it’s true position for the point.

Planimetric Features:
Ninety percent (90%) of all planimetric features, which are well defined on the photographs, shall be plotted so that their position on the manuscript shall be accurate to within at least 1/40 of an inch (0.64mm) of their true coordinate position. None of the features shall be misplaced on the manuscript by more than 1/20 of an inch (1.27mm) from their true coordinate position. Partially obscured planimetric details that may not meet this requirement will be shown by dashed lines where possible. Planimetric features totally obscured will not be shown.

Quality Control:
It is your responsibility and/or the subsequent users to perform field comparisons and sufficient quality control to determine suitability and acceptance of said mapping for it’s intended use, and assume all risk and liability in connection therewith. Eastern Topographics’ liability is hereby limited to warranty and accuracy of said mapping within the expense of flying, photography, and compilation. Any errors or omissions, as determined by field editing, will be corrected by Eastern Topographics at no additional expense. Failure to notify Eastern Topographics within sixty (60) days of any errors and/or omissions, shall be deemed an acceptance of the map and any claims as a result of such defect are waived.

The above Map Accuracies apply only to the contracted map scale and contour interval. In the event that digital terrain information is delivered in the form of breaklines and spot elevations, you and subsequent users are responsible for verifying that subsequent terrain model generation in other software environments conforms to the final mapping product delivered. Any photographic enlargement, retracing or other reproduction of the original delivered products are not covered by these same warranties, since copies may not meet National Map Accuracy Standards. This caution applies especially to digitized mapping delivered in a digital electronic format and subsequently used at a different scale from that originally compiled.