| Addresses |
| Rural addresses/house numbers are assigned and maintained by Ogle County Planning & Zoning Department in the unincorporated areas of Ogle County. Incorporated cities and villages assign addresses within their respective jurisdictions. Cities/villages will forward address assignments, either as assigned or periodically, to the Ogle County Planning & Zoning Department for digitization. The unincorporated rural addresses/house numbers are digitized as they are assigned. |
| Parcels |
| Bruce Harris & Associates of Batavia, IL has created GIS Parcel Information layers for Ogle County. The process includes collecting the original sectional surveys and placing section boundaries on the orthophotography using the surveyed measurements as best as possible. All hydrography is redrawn based on the visible evidence on the digital orthophotography. Road right-of-way information is placed based on any strip map information as well as dimensions on the current tax maps. Then all subdivisions with appropriate distance and bearing calls are placed using coordinate geometry and placed on the orthophotography. What cannot be placed using coordinate geometry is mapped based on the legal descriptions in the tax data and measurements on the current tax maps. Parcel Identification Numbers (PIN) are placed on every parcel. When parcel polygons are created, these numbers are placed in the attribute table and serve as the link between the computerized tax system and the GIS. Other source data referenced are the current tax parcel maps used in the Ogle County Supervisor of Assessments Office and legal descriptions found in the tax database. Digitally combining, all these resources along with digital orthophotography creates a solid, highly accurate parcel base, which is the foundation for the Ogle County GIS. Parcels are maintained and updated by the Ogle County Supervisor of Assessments with the digital gis data updated by the GIS Coordinator. |
| Planimetrics |
| 2' contours can be purchased by quarter section. Currently 10' contours are available in USGS DLG format. |
| PLSS/Control Points |
| PLSS consists of Township, Range, and Section divisions. This layer also contains several types of control points. In 2002, many NGS benchmarks were recovered and mapped by Ogle County Highway Department staff. The points utilized by Ogle County air photo rectification are listed with the type of monument to be found at that location. These points would be considered semi-permanent. Another type of monument to be found in this layer are brass tablets placed in bridges and box culverts by the Ogle County Highway Department. The accuracy of all the above points is listed in the data on each point. All these points have 3-dimensional data utilizing Illinois State Plane coordinates with NAD83 datum. |
| Soils |
| The soils layer is a part of the National SSURGO database maintained by the USDA-NRCS Soil Survey Division. Their website has more information SSURGO soils data. STATSGO soil information is available. The Soils layer for the balance of the County will be completed by USDA-NRCS by December 2004. |
| Street Centerlines |
| Surdex Corporation created the 3-dimensional street centerlines utilizing a proprietary process. The vertical component, elevation, is based upon Illinois State Plane, NAD 83 feet. The Ogle County Highway Department maintains geo-coded attributes along with surface type, jurisdiction, and many other highway attributes. The GIS Department updates the centerline file on a continous basis. |
| Zoning/Jursidictional Limits |
| Zoning district boundaries are maintained by Ogle County Planning & Zoning Department. The County and every incorporated city and village has a unique zoning scheme. The County zoning districts are updated as changes to the official zoning map occur (usually on a monthly basis). The city and village zoning districts are also updated as changes to the official city or village zoning map made. |
| Ortho Photography - Aerials available 1998, 2002 and 2005 |
| The 2002 aerial images are a combination of two sources of orthophotography. The orthophotography in the rural areas was completed by USGS Eros Data Center. The orthophotography in the urban areas was completed by Surdex Corporation. A Digital Orthophoto Quadrangle (DOQ) is a computer-generated image of an aerial photograph in which the image displacement caused by terrain relief and camera tilt has been removed. The DOQ combines the image characteristics of the original photograph with the georeferenced qualities of a map. The Surdex orthophotography was flown in April of 2001 at a scale of 1"=100'. This orthophotography covers the populated areas of the county. Once the digital imagery is oriented, terrain data is used to complete the orthophoto process through digital differential rectification. Surdex uses the cubic convolution re-sampling technique, which is more accurate than either nearest neighbor or bilinear interpolation (of unknown values) techniques. In 2005 the Ogle County Partnership had the entire county flown at 6" resolution. The imagery was oriented to the Illinois State Plane West, NAD83, feet. In November 2006, the aerials were finally accepted and available to the public. A copy of this aerial set is available (See Data Fees) on a cost fee basis. The data set is in TIF format, which is 100% compatible with most platforms including ArcInfo, ArcGIS, ArcView, Mapinfo, and other GIS/CAD software. Each digital ortho tile was inspected for: -Out of focus imagery, image smear -Scanning artifacts -Tile mismatches -Mosaic mismatches, and radiometric color balance -Black lines -Bridges, overpasses, elevated or depressed surfaces -Positional accuracy of Quality Control points The geometric accuracy of a product can be statistically evaluated through the analysis of error propagation. |
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1989 IL Rt. 2, South
Oregon, IL 61061
815-732-2851
gis@oglecounty.org