Cuyahoga County Planimetric Geospatial Data

Conversion To Latitude/ Longitude Coordinate System

In ArcInfo^TM and MapInfo^TM Formats

The Northern Ohio Data & Information Service (NODIS) in The Urban Center of the Maxine Goodman Levin College of Urban Affairs at Cleveland State University are making available a series of geospatial data sets of 18 planimetric data layers for Cuyahoga County and two miles outside the county border.

The methodology used to convert data from its original format to a latitude/ longitude coordinate system and to ArcInfo^TM and MapInfo^TM formats⁽¹⁾ is described below.

Background

The data in these files represent all lines, polygons, and text as seen on selected planimetric layers from digital orthophotographs. They were developed from files supplied originally by the Cuyahoga County Engineer's Office in .dwg (AutoCAD^TM) format. The Cuyahoga County Engineer contracted Aerocon Photogrametric Services Inc. to create digital orthophotographs and to develop these files in AutoCAD^TM file format. The AutoCAD^TM files are used by the Cuyahoga County Engineer for project-specific engineering work. The files are current as of March 1993.

In order to make these data useful to other users of Geographic Information Systems (GIS), three obstacles had to be overcome. First, the County’s files were developed using the Cleveland Regional Geodetic Survey (CRGS) as the coordinate system. This coordinate system is locally unique and prevents other potential users of the data to overlay (combine and relate) other geospatial data which are developed in more common coordinate systems such as latitude/longitude or state plane coordinates.

Second, many GIS users use ArcInfo^TM and/or MapInfo^TM software and may have difficulty importing and using AutoCAD^TM drawing data.

Third, the data layers were originally created in over 900 AutoCAD^TM drawing files (.dwg), and each map was comprised of many data layers covering 4,000-foot by 5,000-foot rectangular areas. With so many files it is laborious to assemble the data for a municipality or other geographic areas of interest. Furthermore, the arbitrary rectangular structure ignores municipal boundaries, adding an obstacle to using the data on a community by community basis.

Thus, in their original format, the data are unavailable and/or difficult to use for many GIS users.

Therefore, NODIS undertook the task of converting the data to latitude/longitude coordinates and to ArcInfo^TM and MapInfo^TM formats, and to create a fewer number of data files.

The converted data are made available on CD-ROM.

Methodology

ArcInfo^TM software was used to build arcs, polygons, and text from AutoCAD^TM .dwg⁽²⁾ data. ArcView^TM v. 3.2 was used to define the CRGS custom projection. The CRGS parameters are based on the revised "McFadden Shift" method. McFaddden was staff member of the Cuyahoga County Engineer's Office. The "McFadden Shift" method and parameters are described in a series of reports produced by the Engineer's Office from the 1930's to the 1950's. Errors of up to 7 feet were observed at the northeastern edges of the county. The Cuyahoga County Planning Commission discovered a "Scale Factor" as well as some other parameter adjustments such as a Stereographic Projection to improve the CRGS projection accuracy. The Planning Commission defined the CRGS projection in MapInfo^TM. NODIS created the CRGS projection in ArcView^TM 3.2 and ArcInfo^TM Beta v. 8.02. The locational accuracy was very similar. The stereographic method was tested using 500 USGS monument and GPS control points that have known x and y coordinate values in CRGS and US State Plane NAD 83 meters. 78% of all the projected points were within 1 foot and 96% were within 2 feet of the known x and y locations of the control points.

(See Figure 1: 500 GPS and USGS Monument Control Points).

The ArcView^TM v. 3.2 projection file associated with the shapefile would be as follows:

96012192]]

The parameters are:

The CRGS projection can then be changed to any standard projection such as US State Plane NAD83 feet or the latitude/longitude coordinate system.

The planimetric files are provided in the latitude/longitude coordinate system since it is a projection-free coordinate system and since it may be difficult for some GIS users to use projection-based coordinate systems such as CRGS and State Plane. 

The CRGS projection can also now be defined in the latest release of ArcInfo^TM beta v. 8.02. Comparisons to the known CRGS coordinate values are the same as is seen in ArcView^TM. However, NODIS discovered that the datum conversion to US State Plane NAD83 (NADCON 1927 to 1983) in ArcInfo^TM Beta v. 8.02 does NOT work at this time (2/15/00).

Accuracy

NODIS does not guarantee the completeness nor accuracy of the data.

Potential errors may result from any combination of the following.

1. The original planimetric data may have some errors of unknown character.
2. The city border data set may not be highly accurate in areas where the city border follows parcel boundaries and not     planimetric features. The source of any such error is in the County’s original planimetric data.

NODIS has overlaid Cuyahoga planimetric and parcel layers. The planimetric data are assumed to contain a higher degree of accuracy than the parcel data. In most areas, the planimetric spatial objects are located relatively accurately to the parcel polygons. This includes road pavement edges and building footprints. There are some areas where the parcel polygons are apparently displaced relative to the planimetric features.

Attribute Data

The data have been converted to ArcInfo^TM export ("e00") and MapInfo^TM formats. The only attribute data fields that are attached to any of the various layers are the following:

• 2 and 10 foot contours - elevation value in feet above sea level
• spot elevations - elevation value in feet above sea level
• city - city name and census code

File Organization

Each layer was created as one file containing geographic coverage for the entire county (plus the two-mile area beyond the county border). The layers are listed below. File names are shown in parenthesis and spatial object type (arcs, points, polygons, and text) are noted in brackets.

(Figure 2: Digital Orthophotograph Index Map shows the original 900 digital orthophoto outline areas.)

Credits

Please provide the following credits in any published report or map

Notes

1. ArcInfo^TM (and its related ArcView^TM) and MapInfo^TM are among the most commonly used Geographic Information System (GIS) software in the world.

2. dwg is an AutoCAD^TM native format..

Prices - Cuyahoga County Parcel Data on CD-ROM

Supplied by Northern Ohio Data & Information Services at Cleveland State University

Contact Jim Wyles at 216-687-2221 or wyles@urban.csuohio.edu

Source data for all files originated from Cuyahoga County Engineer, current as of March 1993.

NODIS cannot guarantee the completeness or accuracy of the source data. Prices may change. Please confirm price when ordering. All data available only on CD-ROM.

Data Compression: The ArcInfo^TM .e00 data on the CD-ROM has been compressed into archive files to reduce the number of CD-ROM disks required to contain the data. Use software compatible with PK-ZIP 2.04g to decompress the data. Info-Zip's software (Zip, Unzip and related utilities) are examples of packages that can be used. The Info-Zip software is free and can be obtained as source code or executables on various computer platforms. One site from which this software can be downloaded is: http://www.cdrom.com/pub/infozip/UnZip.html

Planimetric files covering all of Cuyahoga County and two miles outside the county border:

Filename = planall.zip 565 MB (uncompressed .e00 = 3.2 GB)

This compressed file, planall.zip, contains the following .e00 files: road (road), road name text (roadlbl), interstate (inst), spot elevation points (spot), railroad (rail), water (wtr), wall (wall), driveway (dvwy), bridge (brdg), recreation polygons (recre), dense tree (dtree), city polygons (city), county polygons (county), original 900 sheet index (planidxl), building footprint polygons (bldg), 2 foot elevation contour lines (elv2), 10 foot elevation contour lines (elvlb), and trees (tree) as lines.

Coordinate system: Latitude/ longitude NAD 83, Northern Ohio Units- decimal degrees

All .e00 files are contained on one CD (565 MB- compressed, 3.2 GB- uncompressed)

Cost…………………… $ 1,200

Planimetric files covering all of Cuyahoga County and 2 miles outside the county border: road (road), road name text (roadlbl), interstate (inst), spot elevation points (spot), railroad (rail), water (wtr), wall (wall), driveway (dvwy), bridge (brdg), recreation polygons (recre), dense tree (dtree), city polygons (city), county polygons (county), original 900 sheet index (planidxl), building footprint polygons (bldg), 2 foot elevation contour lines (elv2), 10 foot elevation contour lines (elvlb), and trees (tree) as lines.

Coordinate system: Latitude/ longitude NAD 83, Northern Ohio Units- decimal degrees

All MapInfo^TM native format files are contained on one CD (578 MB)

Cost…………………… $ 1,200