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Definition
OHIO BASEMAP README FILE OHIO DEPARTMENT OF NATURAL RESOURCES DIVISION OF GEOLOGICAL SURVEY This readme file gives a short explanation on the Ohio Basemap files that the Ohio Geological Survey distributes as part of the Oil & Gas Well Location Digitizing project. Contact Information: For further information with, or information about these files, please contact: James McDonald Ohio Department of Natural Resources Division of Geological Survey 4383 Fountain Square Drive Columbus, OH 434224 Phone: 614-265-6601 E-mail: jim.mcdonald@dnr.state.oh.us Web Site: http://www.dnr.oh.us/odnr/geo_survey/ 1. TYPES OF MAPS AVAILABLE There are three types of files available to the public on the CD-ROM. There are two types of county files, the background and the road files. The background files have the naming convention of the following: WAY_SPN.DWG Where the first three letters generally stands for the first three letters of a county name, the SPN or SPS stands for the coordinate system of the digital file. In these cases, SPN stands for Ohio State Plane Coordinate System - North Zone, using the North American Datum of 1927 (NAD27). SPS stands for Ohio State Plane Coordinate System - South Zone, using the North American Datum of 1927 (NAD27). The road files have the naming convention of the following: WAYRTE_SPN.DWG Where the first three letters generally stands for the first three letters of a county name, the RTE indicates that the file contains the roads for the county, and the SPN or SPS stands for the coordinate system of the digital file. In these cases, SPN stands for Ohio State Plane Coordinate System - North Zone, using the North American Datum of 1927 (NAD27). SPS stands for Ohio State Plane Coordinate System - South Zone, using the North American Datum of 1927 (NAD27). We have also included two statewide base maps. These are named STATE_SPN.DWG and STATE_SPS.DWG. These base maps contain only the original ODOT features. They do not contain any of the U.S. Geological Survey DLG features. Therefore, these two should only be used for statewide displays, not for any detailed county or township displays. These maps are not accurate at the County and Township level. 2. LAYER NAMES Background File Layer Names (XXX_SPX.DWG) Layer Name 2 County Polygon 3 Township Polygon 5 Corporation Polygon 6 Urban Area Polygon 7 Census Area Polygon 8 Unicorp Polygon 9 Airport Boundary 10 Quad Lines and Monuments 11 State Lines 12 County Lines 13 Township Lines 14 Section Lines 15 Corporation Lines 16 Urban Area Lines 17 Census Area Lines 18 Unicorp Lines 19 Airport Runway 20 Quad Name 21 State Name 22 County Name 23 Township Name 24 Section Name 25 City Name 26 Urban Area Name 27 Census Area Name 28 Unicorp Name 29 Airport Name 30 Major Lake Polygon 31 Major River Polygon 32 Minor Lake Polygon 33 Minor River Polygon 34 Other Hydro Polygon 35 Irregular Subdivision Lines-Lots or small subdivisions 36 Irregular Subdivision Lines-Intermediate subdivisions 37 Irregular Subdivision Lines-Large subdivisions 38 Section Lines not found on the 1:24,000-scale topographic maps or 1:24,000-scale DLG files 39 Rail Lines 40 Major Lake Linework 41 Major River Linework 42 Minor Lake Linework 43 Minor River Linework 44 Other Hydro Linework 45 Irregular Subdivision Text-Lots or small subdivisions 46 County Road Name 47 Township Road Name 48 City Street Name 49 Rail Line Name 50 Major Lake Name 51 Major River Name 52 Minor Lake Name 53 Minor River Name 54 Other Hydro Name 55 Interchange layout 56 Irregular Subdivision Text-Intermediate subdivisions 57 Irregular Subdivision Text-Large subdivisions 58 Section Text not found on the 1:24,000-scale topographic maps or 1:24,000-scale DLG files 60 Township Number (assigned by ODOT) 61 Route Shield Punch Out 62 Route Shield Lines & Text Route File Layer Names (XXXRTE_SPX.DWG) Layer Name 11 Interstate 12 United States Route 13 State Route 14 Turnpike 15 Proposed State System 21 County Principal, Mileage Class=1 22 County Subdivision, Mileage Class=2 23 County Within Corp., Mileage Class=8 32 Township Principal, Mileage Class=1 33 Township Subdivision, Mileage Class=2 34 Township Within Corp., Mileage Class=8 41 Municipal Street Statewide Basemap File Layer Names (STATE_SPN.DWG and STATE_SPS.DWG) Layer Name 1 API County Codes 2 State Outline-Thin lines 11 State Outline-Thick Lines 12 County Lines 13 Township Lines 20 County Names-Small 21 County Names-Large 22 Township Names-Large 50 Township Names-Small 3. GENERAL PROCESS IN CONSTRUCTING THE BASEMAP FILES From: McDonald, J., Wickstrom, L.H., and Steck, C.D., 1997, History of Ohio's Oil-and Gas-Well Location Maps and Their Conversion to Digital Form, in Ohio Geological Society Fifth Annual Technical Symposium, Akron, Ohio, November 12, 1997: Ohio Geological Society, Columbus, Ohio, p. 52-64. To produce any sort of accurate product in this digitization effort, it was necessary to register our inaccurate paper and mylar township spot maps to an accurate representation of the land subdivisions for Ohio. This process is known as "rubber-sheeting." Via a process called digitizer setup, the operator registers a number of points on the mylar map (minimum of four points) to corresponding points on the digital map. The computer program then stretches and squeezes the input to minimize error over that area. The setup program reports error statistics that allow us to judge how accurate our representation will be. Our accuracy requirements for spotting wells on a base map must be less than 100 feet. Some of the mylar townships were so distorted that a digitizer setup had to be run on each section/subdivision in the township. Therefore, the success of this project largely depended on the accuracy of the digital base map that we used. There have been a number of previous efforts to build a digital base map for Ohio, the first started in the early 1980's by the Ohio Department of Transportation (ODOT). Between 1980 and 1985 ODOT digitized the following elements from the U.S. Geological Survey 1:24,000-scale topographic maps: 7.5-minute quadrangle boundaries; political boundaries such as state, county, township, and municipal boundaries; Public Land Survey System (PLSS) boundaries (sections); roads and railroads; airport locations; and hydrography (streams and lakes). Another effort to build a contiguous statewide base map was initiated by the Public Utilities Commission of Ohio in the late 1980's. These files did not include the PLSS section lines, which were of critical importance to our project. There are other small-scale digital base maps that are available for use, such as the U.S. Bureau of the Census TIGER files and the U.S. Geological Survey 1:100,000-scale digital line graph (DLG) files. Both the TIGER files and the 1:100,000-scale DLG files were considered to be too inaccurate for spotting the locations of the oil and gas wells. In addition, the TIGER files did not include the PLSS section lines, and the 1:100,000-scale DLG files did not completely cover the entire state. The Survey had been using ODOT's digital base maps since 1987 for smaller scale mapping projects and, therefore, we were familiar with their structure. When we started this project we thought these files would be sufficient for us to build upon. Unfortunately, we discovered a number of problems associated with these files. First, although ODOT did perform quality control on the layers that were of importance to their mapping, the PLSS lines were not a priority so did not have very rigorous quality control performed. Initial comparison of the PLSS lines between the paper 1:24,000-scale- topographic maps and the digital files showed errors ranging up to 500 feet. The PLSS layer was one of the most critical features needed for our project. We had hoped that by using ODOT's section lines, we would only have to digitize the irregular subdivisions in the state. The second major problem discovered in the ODOT files was the Ohio State Plane Coordinate System zone boundary. By law, the Ohio State Plane Coordinate System zone boundary falls along a specified set of county lines (Ohio Revised Code, 1985). When ODOT digitized those counties and quadrangles that fall along the zone boundary, they introduced a distortion so that neighboring counties in different zones could be merged seamlessly together without a coordinate transformation. This distortion ranges anywhere from 0 to 200 feet for those boundary counties, depending upon distance from the principal meridian. This distortion affected elements within those county files, rendering them useless for our needs. Luckily, several Ohio state agencies, including ODNR, are involved in a cooperative agreement with the U.S. Geological Survey (USGS) to convert all the USGS 1:24,000-scale topographic maps to digital line graph (DLG) files. The resultant DLG files are very accurate digital representations of the elements comprising the 7.5-minute quadrangles. The contractor for the project was The Ohio State University's Center for Mapping. The project is known as Generating Information from Scanning Ohio Maps (GISOM) (Ramirez, 1997). The DLG files, when complete, will represent the most accurate, contiguous, and consistent set of digital base maps available across the state of Ohio. To obtain the U.S. Geological Survey DLG files from the State of Ohio over the Internet, please access the Ohio DLG Web Site: http://www.geodata.state.oh.us/dlg/ . To obtain the DLG data on CD-ROM, or if you have any other questions, please call the State of Ohio's GIS Support Center at 614-644-8041 or send e-mail to dlg@ohio.gov. Using the new DLG files was considered our best solution for a number of reasons. These data conform to the National Map Accuracy Standards for 1:24,000 scale, which translates to an accuracy of 40 feet (U.S. Bureau of the Budget, 1947), which meets our accuracy needs. Another reason for using the U.S. Geological Survey DLG maps is because they include the hypsography (topographic contours). No other map series in the United States has as detailed hypsography as this map series. The final, and most compelling, reason to use the DLG files is the accuracy of the PLSS features. Although the USGS does not claim legal responsibility for the accuracy of the PLSS data, it was discovered that considerable effort was made to recover the PLSS section corners for Ohio. According to the specifications used to create the topographic maps (U.S. Geological Survey, 1980), all efforts must be made to recover the PLSS section corners so that the PLSS lines can be represented accurately. Examination of the original source materials stored at the USGS offices in Rolla, Missouri revealed that the mapmakers and surveyors collected, in the field, the locations of the original section corners. The surveyors used copies of the original survey plats from 1786 to 1820 to survey and recover the section corners. These copies of the plats came from the National Archives in Washington, D.C. This effort to accurately recover and represent the section corners gave us confidence that this map series would meet the needs of the oil and gas industry to locate wells throughout the state of Ohio. Unfortunately, the GISOM project was not completed by the time we needed the base map for this project. After we had finished capturing well locations and attributes for the western half of the state, we discovered that the ODOT base map we were using was not accurate enough for our purposes. We then had to start over again and build the base map using the DLG files. But, because the GISOM project was not completed at that point, we had to digitize some of the political boundaries and PLSS section lines from the 1:24,000-scale topographic maps. The quality-control checking of our digitizing of the political boundaries and PLSS lines indicates that our work is within National Map Accuracy Standards. We plan to go back and substitute in the newly released DLG files for those quadrangles we had digitized. Because our digitizing conforms to the National Map Accuracy Standards, replacing our digitizing with the DLG data will not degrade the accuracy of the digitized well locations. In addition, the DLG files were supplemented by adding the original, irregular land subdivisions. Ohio was the first state in which the federal government subdivided the land before it was sold. This process started in 1785, right after the end of the Revolutionary War. Between 1786 and 1838, many different schemes were used to subdivide the land. In Ohio, nine major schemes were used, along with many different minor subdivisions (Sherman, 1925). Eventually, the federal government settled upon the scheme that is now known as the Public Land Surveying System (PLSS). This system was first applied in the United States in northwestern Ohio. The PLSS layer in the DLG files does not include the irregular land subdivisions of Ohio. These irregular subdivisions occur in the following surveying districts: Virginia Military District, Ohio Company Purchase, Donation Tract, Connecticut Western Reserve, and U.S. Military District. There are also numerous other small surveys in which irregular subdivisions occur, such as the French Grants, Refugee Grants, the Twelve-Mile-Square Tract; these divisions are well described in Sherman (1925). There are many wells located by footage calls in these areas of irregular land subdivisions. Therefore, it was important that we add the irregular land subdivisions to the PLSS layer of the DLG files. We needed to capture the irregular land subdivisions for our work to accurately digitize the well locations. The process that we used involved digitizing the irregular land-subdivision lines from the county engineer tax maps. In some cases, the irregular land- subdivision lines were not reliable or could not be read from the tax maps. In those cases, we used alternative sources for the irregular land subdivisions. These sources included Ohio Fuel Gas township-well-spot maps, Ohio Division of Geological Survey county base maps, county plat books, Pure Oil Company township well-spot maps, larger scale subdivisions from Sherman (1925), Sherman's (1922) map (used as a secondary source of Virginia Military District lots), and the Quaker State Oil Company base maps (used especially as a tertiary source for the Virginia Military District lots). We would do a digitizer setup of a township tax map to the digital base map assembled from the DLG's. If the misclosure between the township map and the digital base map was greater than 50 feet, then a digitizer setup was performed on a smaller area of the tax map. Once an acceptable digitizer setup was established, the operator digitized the irregular land-subdivision lines into the graphics file. Our resultant digital base-map series now contains new county, township, section and irregular subdivision lines either captured from DLG files or digitized at the Survey. The digital ODOT files have been rectified to fit these new bases to allow us to use their hydrography and textual labeling. In the near future, we plan to bring in the hypsography, hydrography, and roads from the new DLG files. We then plan to add major roads and streams to the new digital township well-spot maps. We also intend to offer 7.5-minute quadrangle well-spot maps, complete with topographic contours, in the near future. Ramirez, J. R, 1997, Generation of consistent digital geographic data for the state of Ohio: the GISOM Project: Proceedings of 1997 national GIS/LIS meeting, Cincinnati Ohio, October 1997, p. 365-373. Sherman, C. E., 1922, Map of Ohio showing original land subdivisions to accompany Volume III, Final Report: Ohio Cooperative Topographic Survey, 1:500,000 scale. ____________ 1925, Original Ohio land subdivisions: Ohio Cooperative Topographic Survey, Volume III of the Final Report, 233 p. U.S. Bureau of the Budget, 1947, United States National Map Accuracy Standards. U.S. Geological Survey, 1980, Public-land subdivisions on 1:24,000-scale maps, in Chapter 4A4, Topographic instructions: U.S. Geological Survey, 14 p. 4. DETAILED INFORMATION ON EACH COUNTY FILE Detailed information is listed on the source of the features in each base map file. All of the ROAD file (RTE files) features come from the original ODOT files. The boundary features in the background files, which include the political boundaries and the PLSS sections, can come from either the U.S. Geological Survey DLG files/in-house digitizing of the 1:24,000-scale topographic maps (the source is indicated as DLG) or from the original ODOT files. The remainder of the background file features, such as the hydrography, railroads, airports, and the text for all the features comes from the original ODOT files. COUNTY File Names Data Sources for Features Adams adarte_sps.dwg Roads-ODOT ada_sps.dwg Boundaries-ODOT Allen all2_spn.dwg Boundaries-DLG allrte_spn.dwg Roads-ODOT Ashland asdrte_spn.dwg Roads-ODOT asd_spn.dwg Boundaries-DLG Ashtabula atbrte_spn.dwg Roads-ODOT atb_spn.dwg Boundaries-DLG Athens athrte_sps.dwg Roads-ODOT ath_sps2.dwg Boundaries-DLG Auglaize aug2_spn.dwg Boundaries-DLG augrte_spn.dwg Roads-ODOT Belmont belrte_sps.dwg Roads-ODOT bel_sps.dwg Boundaries-DLG Brown brorte_sps.dwg Roads-ODOT bro_sps.dwg Boundaries-ODOT Butler butrte_sps.dwg Roads-ODOT but_sps.dwg Boundaries-ODOT Carroll carrte_spn.dwg Roads-ODOT car_spn.dwg Boundaries-DLG Champaign chp2_sps.dwg Boundaries-DLG chprte_sps.dwg Roads-ODOT Clark clarte_sps.dwg Roads-ODOT cla_sps.dwg Boundaries-ODOT Clermont clerte_sps.dwg Roads-ODOT cle_sps.dwg Boundaries-ODOT Clinton clirte_sps.dwg Roads-ODOT cli_sps.dwg Boundaries-ODOT Columbiana colrte_spn.dwg Roads-ODOT col_spn.dwg Boundaries-DLG Coshocton cosrte_spn.dwg Roads-ODOT cos_spn.dwg Boundaries-DLG Crawford crarte_spn.dwg Roads-ODOT cra_spn.dwg Boundaries-ODOT Cuyahoga cuyrte_spn.dwg Roads-ODOT cuy_spn.dwg Boundaries-DLG Darke darrte_sps.dwg Roads-ODOT dar_sps.dwg Boundaries-ODOT Defiance defrte_spn.dwg Roads-ODOT def_spn.dwg Boundaries-ODOT Delaware del2_spn.dwg Boundaries-DLG delrte_spn.dwg Roads-ODOT Erie erirte_spn.dwg Roads-ODOT eri_spn.dwg Boundaries-DLG Fairfield fairte_sps.dwg Roads-ODOT fai_sps.dwg Boundaries-DLG Fayette fayrte_sps.dwg Roads-ODOT fay_sps.dwg Boundaries-ODOT Franklin frarte_sps.dwg Roads-ODOT fra_sps.dwg Boundaries-DLG Fulton fulrte_spn.dwg Roads-ODOT ful_spn.dwg Boundaries-ODOT Gallia galrte_sps.dwg Roads-ODOT gal_sps2.dwg Boundaries-DLG Geuaga gearte_spn.dwg Roads-ODOT gea_spn.dwg Boundaries-DLG Greene grerte_sps.dwg Roads-ODOT gre_sps.dwg Boundaries-ODOT Guernsey guerte_sps.dwg Roads-ODOT gue_sps.dwg Boundaries-DLG Hamilton hamrte_sps.dwg Roads-ODOT ham_sps.dwg Boundaries-ODOT Hancock hanrte_spn.dwg Roads-ODOT han_spn.dwg Boundaries-ODOT Hardin har2_spn.dwg Boundaries-DLG harrte_spn.dwg Roads-ODOT Harrison hasrte_spn.dwg Roads-ODOT has_spn.dwg Boundaries-DLG Henry henrte_spn.dwg Roads-ODOT hen_spn.dwg Boundaries-ODOT Highland higrte_sps.dwg Roads-ODOT hig_sps.dwg Boundaries-ODOT Hocking hocrte_sps.dwg Roads-ODOT hoc_sps.dwg Boundaries-DLG Holmes holrte_spn.dwg Roads-ODOT hol_spn.dwg Boundaries-DLG Huron hurrte_spn.dwg Roads-ODOT hur_spn.dwg Boundaries-DLG Jackson jacrte_sps.dwg Roads-ODOT jac_sps2.dwg Boundaries-DLG Jefferson jefrte_spn.dwg Roads-ODOT jef_spn.dwg Boundaries-DLG Knox knorte_spn.dwg Roads-ODOT kno_spn.dwg Boundaries-DLG Lake lakrte_spn.dwg Roads-ODOT lak_spn.dwg Boundaries-DLG Lawrence lawrte_sps.dwg Roads-ODOT law_sps2.dwg Boundaries-DLG Licking licrte_sps.dwg Roads-ODOT lic_sps2.dwg Boundaries-DLG Logan log2_spn.dwg Boundaries-DLG logrte_spn.dwg Roads-ODOT Lorain lorrte_spn.dwg Roads-ODOT lor_spn.dwg Boundaries-DLG Lucas lucrte_spn.dwg Roads-ODOT luc_spn.dwg Boundaries-ODOT Madison madrte_sps.dwg Roads-ODOT mad_sps.dwg Boundaries-ODOT Mahoning mahrte_spn.dwg Roads-ODOT mah_spn.dwg Boundaries-DLG Marion mar2_spn.dwg Boundaries-DLG marrte_spn.dwg Roads-ODOT Medina medrte_spn.dwg Roads-ODOT med_spn.dwg Boundaries-DLG Meigs megrte_sps.dwg Roads-ODOT meg_sps2.dwg Boundaries-DLG Mercer mer2_spn.dwg Boundaries-DLG merrte_spn.dwg Roads-ODOT Miami miarte_sps.dwg Roads-ODOT mia_sps.dwg Boundaries-ODOT Monroe moerte_sps.dwg Roads-ODOT moe_sps.dwg Boundaries-DLG Montgomery motrte_sps.dwg Roads-ODOT mot_sps.dwg Boundaries-ODOT Morgan mrgrte_sps.dwg Roads-ODOT mrg_sps.dwg Boundaries-DLG Morrow mrw2_spn.dwg Boundaries-DLG mrwrte_spn.dwg Roads-ODOT Muskingum musrte_sps.dwg Roads-ODOT mus_sps2.dwg Boundaries-DLG Noble nobrte_sps.dwg Roads-ODOT nob_sps.dwg Boundaries-DLG Ottawa ottrte_spn.dwg Roads-ODOT ott_spn.dwg Boundaries-ODOT Paulding paurte_spn.dwg Roads-ODOT pau_spn.dwg Boundaries-ODOT Perry perrte_sps.dwg Roads-ODOT per_sps.dwg Boundaries-DLG Pickaway picrte_sps.dwg Roads-ODOT pic_sps.dwg Boundaries-DLG Pike pikrte_sps.dwg Roads-ODOT pik_sps2.dwg Boundaries-DLG Portage porrte_spn.dwg Roads-ODOT por_spn.dwg Boundaries-DLG Preble prerte_sps.dwg Roads-ODOT pre_sps.dwg Boundaries-ODOT Putnam putrte_spn.dwg Roads-ODOT put_spn.dwg Boundaries-ODOT Richland ricrte_spn.dwg Roads-ODOT ric_spn.dwg Boundaries-DLG Ross rosrte_sps.dwg Roads-ODOT ros_sps2.dwg Boundaries-DLG Sandusky sanrte_spn.dwg Roads-ODOT san_spn.dwg Boundaries-ODOT Scioto scirte_sps.dwg Roads-ODOT sci_sps2.dwg Boundaries-DLG Seneca senrte_spn.dwg Roads-ODOT sen_spn.dwg Boundaries-ODOT Shelby she2_spn.dwg Boundaries-DLG sherte_spn.dwg Roads-ODOT Stark starte_spn.dwg Roads-ODOT sta_spn.dwg Boundaries-DLG Summit sumrte_spn.dwg Roads-ODOT sum_spn.dwg Boundaries-DLG Trumbull trurte_spn.dwg Roads-ODOT tru_spn.dwg Boundaries-DLG Tuscarawas tusrte_spn.dwg Roads-ODOT tus_spn2.dwg Boundaries-DLG Union uni2_spn.dwg Boundaries-DLG unirte_spn.dwg Roads-ODOT Van Wert van2_spn.dwg Boundaries-DLG vanrte_spn.dwg Roads-ODOT Vinton vinrte_sps.dwg Roads-ODOT vin_sps2.dwg Boundaries-DLG Warren warrte_sps.dwg Roads-ODOT war_sps.dwg Boundaries-ODOT Washington wasrte_sps.dwg Roads-ODOT was_sps.dwg Boundaries-DLG Wayne wayrte_spn.dwg Roads-ODOT way_spn.dwg Boundaries-DLG Williams wilrte_spn.dwg Roads-ODOT wil_spn.dwg Boundaries-ODOT Wood woorte_spn.dwg Roads-ODOT woo_spn.dwg Boundaries-ODOT Wyandot wyarte_spn.dwg Roads-ODOT wya_spn.dwg Boundaries-ODOT |
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