DIGITIZED & VECTORIZED USGS 7.5' QUADRANGLE MAPS
*(click states for lists)*
AL, IL, IN, KY, MD, MN, OH, PA, TN, UT, VA, WV, WY,
Eastham & Associates brings a unique perspective to Quadrangle conversion in the form of our surveying and mapping expertise. Our Owner, Mr. Ronald L. Eastham, RPS, is a Licensed Professional Surveyor in Kentucky, West Virginia and Ohio. The firm also employs four additional experienced Licensed Professional Surveyors and Engineers. All this culminates in a mapping product that reflects professional attention to detail, understanding of coordinate systems, comprehension of accuracy issues, and appreciation for mapping aesthetics.
Our personnel are proficient in Quadrangle data conversion. Our inventory of Quadrangle maps is constantly increasing. In fact, we have filled orders for 681 different Quadrangles (for portions of* AL, IL, IN, KY, MD, MN, OH, PA, TN, UT, VA, WV, and WY ) *(click for lists), most to repeat customers who have referred to our Quadrangles as 'the best in the country'. Some uses of the Quadrangles have included GIS base mapping, preliminary route layout design, coal company mine permit mapping and gas exploration projects.
BACKGROUND
METHODOLOGYSupport of a GIS/AM solution for management of mapping projects requires the conversion of Quadrangles into vectorized format compatible with AutoCAD™ Releases 12, 13 and 14. The goal of the conversion effort is to produce digital data that matches the original Quadrangles in accuracy, appearance and usefulness, and edge-matched.
By converting the 7.5-Minute Quadrangles into AutoCAD™ .DWG format, designers will be able to capitalize on new technology and automation procedures while maintaining the integrity of the original product. Digitized/vectorized format allows map entities to be manipulated to accommodate any drawing or design needs.
Eastham & Associates reproduces the original 'hardcopy' Quadrangle as closely as possible in digital format. Each map is individually scanned and vectorized into .DWG format from film mylars of the original photographic stable-base maps (maintained by USGS, TVA or other authority) to give the very best final product. The original 'hardcopy' Quadrangles are printed by combining these 'separates' to form the final published Map. (The Vegetation is not normally provided due to the changes that are inherent to vegetation areas, but may be added to the order if requested).PRODUCTIONThe raster images of the Planimetrics and Revisions separates are screen digitized manually. Topographic symbols are individually inserted at the proper rotation. Roads, Railroads, Utility lines, Fence lines, Cemetery lines, Corporate limits and other similar lines are digitized as continuous polylines. Line, Block and Text conform to the USGS symbolism. If preferred, layering can be defined according to the clients' individual needs for a nominal at-cost fee.
The raster images of the Contour and Drainage separates are vectorized with a raster to vector conversion unit. Contours are continuous 2D polylines with assigned elevation or Z values. The cleanup process for the Contour separate involves several steps utilizing proprietary methods and in-house software to perform the quality control procedures.
The final 7.5-Minute Quadrangle Map is translated to the appropriate State Plane Coordinate System. The longitude and latitude values are used to calculate the State Plane Coordinate System X and Y values for each border corner. The separate drawing files are then merged and visually inspected for proper registration. Additional raster registration techniques are available and this process can be modified if desired. Each map is edge-matched to adjoining maps as they are completed. The map entities that cross sheets' borders are manually adjusted to match those of the adjacent completed maps.
For Quadrangles not in stock, it takes approximately three weeks for the T.V.A. and one week for U.S.G.S. to fill an order for the stable-base maps. Upon receipt, the Quadrangle is scheduled in with our current production and processed according to the clients' priority. Deliveries of Quadrangles are made on CD-ROM. Each Quadrangle ranges from 10 to 20 megabytes in size depending on the contour interval and terrain.
Our standard License permits unlimited use of a Quadrangle at one office or place of business. Call 1-800-424-5258 for up to date pricing on a complete 7.5-Minute Quadrangle map or Planimetrics only quadrangle map.
Completed Quadrangles are proprietary and are ready for sale.
