Geographic Information System
A successful Geographic Information system (GIS) is built and not bought. This is because GIS is data-driven and the effective use of GIS relies on accurate and up-to-date information being available to improve the service efficiency of an organization. Often this information is dependent on other agencies to create, update and maintain. GIS, successfully implemented in an organization, is a technology that enables the non-GIS staff to be more productive and more accurate in performing their daily work, resulting in the institutionalizing (embedding) of technology in the workflows. This is an incremental process. CAGIS continues to support and create an environment of trust, success and credibility to secure long-term commitment and support at all levels of the organization for change.
CAGIS manages over 200 map information layers with many of them contributed and maintained by participating agencies. This shared dataset is the underlying foundation for the integration and coordination framework over which all agency processes are automated for effective service delivery. This dataset also supports analysis, decision making, planning, community participation and a host of other services.
What types of GIS data are available through CAGIS?
CAGIS data can be categorized into these general categories, which are made available to the public via digital data or online channels:
- Planimetric data – outlines of land features visible from aerial photography, which include building structures, pavement edges, driveways, parking lots, sidewalks, trails, walls and guardrails, poles, rivers and streams, etc.
- Ownership/administrative data – Property ownership boundaries, municipal and township boundaries, zoning and land use, census tracts and blocks, etc.
- Workflow/transactional data - addresses, past and current road construction project areas, building permits and inspection records, etc.
- Raster data – aerial imageries and scanned historic photos
- Underground utility data – water, storm water and sewer utility data are maintained by CAGIS consortium members, data can be obtained only through the Greater Cincinnati Water Works (GCWW) and Metropolitan Sewer District (MSD) on project-by-project basis.
What CAGIS data can be used for:
- Preliminary site planning and design
- Feature locating and mapping
- GIS analysis and spatial data processing (for example, geocoding)
- Base map for asset management, traffic routing, emergency response, etc.
What CAGIS data are NOT for:
- Insurance claims for property damage or damages due to flooding
- Legal case supporting materials without prior court approval
- Sole source for engineering design of building, road and utility construction
How accurate are CAGIS Data?
All CAGIS data meet or exceed the National Map Accuracy Standards for 1"=100’ base map for both horizontal and vertical accuracy:
- Horizontal (positional) – ± 2 foot
- Vertical (contour elevation) – ± 1 foot
How are CAGIS data created and maintained?
All CAGIS planimetric data were created using the industrial standard photogrammetric procedures. Utilizing highly specialized hardware and software, visible land features are identified in aerial photography and painstakingly digitized by trained professionals.
Prior to 2011, all CAGIS contour data were captured using stereoscopic triangulation method - the standard process to produce high accuracy elevation contours. In 2011, CAGIS chose LIDAR (Light Detection and Ranging) technology to produce its contours. LIDAR captures "clouds" of elevation points based on which contours are generated.
CAGIS property boundary data are based on professional survey information, the metes and bounds of property surveys are recorded in mapping using coordinate geometry (COGO).
CAGIS also maintains real-time address and street information as part of its geographic information framework that is integrated with all of its enterprise GIS and permitting operations. The address and street layers provide the most complete and up-to-date location information for Hamilton County and for part of the surrounding communities.
How CAGIS data and services are made available to the public?
- Digital data sales – all CAGIS data categories above in either AutoCAD DXF, ESRI shape or file geodatabase format, raster data are in MRSID, TIFF or JPG formats.
- Map sales – standard paper maps of various scales up to 36 inches x 60 inches
- Free online services:
- CAGIS Online – online resource for CAGIS maps and property reports
- CAGIS GIS Download Page - set of GIS layers available for download
- eZTrak Online – online resource for permitting application process
- Requesting Map and Data Services
How often does CAGIS acquire aerial imageries and what is the latest aerial orthophotography CAGIS provides?
- CAGIS updates partially or completely its planimetric data every five years
- CAGIS updates countywide 2’ interval contours completely every 10 years
- CAGIS acquired its latest aerial imageries in March, 2011. The latest aerial imageries cover the entire Hamilton County and part of Butler, Warren and Clermont counties in Ohio.
What is aerial orthophotography? What are the different types of orthophotography CAGIS offers?
An orthophoto, orthophotography or orthoimage is an aerial photograph geometrically corrected ("orthorectified") such that the scale is uniform: the photo has the same lack of distortion as a map. Unlike an uncorrected aerial photograph, an orthophotograph can be used to measure true distances, because it is an accurate representation of the Earth's surface, having been adjusted for topographic relief, lens distortion, and camera tilt inherited from the aerial photo capturing process.
- True color orthophotography – 24 bit seamless color imageries of the red, green and blue (RGB) bands of the electromagnetic spectrum
- Infrared orthophotography – additional near infrared band of the electromagnetic spectrum, typical use of infrared imageries is land cover classification.
- Leaf-on orthophotography – photography usually taken in May or early June, the imageries are ideal for tree canopy inventory and green space management applications.
Where can I find help in using CAGIS Online?
We have created several documents to help you get started using CAGIS Online: