Text · page 52 of 67
Read the whole document on one page (all 67 pages, each with its own heading)
maps at 1:20,000 or smaller, not more than 10% of the well-defined map points tested must be more than 1/50 inch (0.508 mm) out of correct position. At 1:24,000, this tolerance translates to a required horizontal accuracy of 40 feet. If by prior agreement with the Department the map product does not conform to National Map Accuracy Standards, then a statement of actual map accuracy should be included in the Documentation above. Furthermore, hydrographic surveys and maps should conform to recommended accuracy standard proposed in the joint USGS, NOS, Coastal Mapping Handbook, 1978, Melvin Ellis editor, U.S. Government Printing Office, Appendix 6. 2. Additional Digital Cartographic File Requirements - The following cartographic construction requirements must be adhered to by the Contractor: a. Edge-matching -- All map sheets must be both visually and coordinate edge- matched with adjacent map sheets. No edge-match tolerance will be allowed. Attributes for splitable features must also be identical. b. Common Boundaries -- All features that share a common boundary, regardless of map layer, must have exactly the same coordinate position of that feature in all common layers. c. Point Duplication -- No duplication of points that occur within a data string is permitted. d. Connectivity -- Where graphic elements visually meet, they must also digitally meet. All confluences of line and polygon data must be exact; "overshoots", "undershoots", "slivers", or "offshoots" are NOT permitted. e. Line Quality -- A high quality cartographic appearance must be achieved. Transitions from straight lines to curvilinear elements must be smooth, with angular inflections at the point of intersection. The digital representation must not contain extraneous data at a non-visible level. There should be no jags, hooks, or zero length segments. Any lines that are straight, or should be straight, should be digitized using only two points that represent the beginning and ending points of the line. f. Polygon Closure -- For area features being digitized, the last coordinate pair must be exactly (mathematically) equal to the first coordinate pair. No line or polygon must cross itself except to join at an actual confluence. All digitized features across map boundaries must be edited to effect smooth and continuous lines. g. Graphic Precision -- Positional coordinates for all digital graphic elements should not be reported to a level of precision greater than one thousandth (.001) of a foot. h. Digitizer Accuracy -- The required RMS error for digitizer accuracy must be 0.003 or better for digital map registration. Contract Number: C1003337 Page 10 of 11, Attachment A-2 – Program Specific Terms and Conditions