Map Specifications

 

The 2005 Statewide Color Orthophotography Project developd seamless, accurate statewide aerial photography and elevation data for use in a GIS. All data are very high resolution and accuracy � meeting the needs of the most demanding users, like local government.

County Buy-Ups

 

The statewide base product was 1-foot resolution imagery (5″ or better accuracy). Thirteen Indiana counties exercised their buy-up option to 6-inch resolution imagery (2.5″ or better accuracy).
Dubois
Elkhart
Floyd
Hamilton
Kosciusko
Lake
LaPorte
Marion
Monroe
Perry
Steuben
Tippecanoe
Vanderburgh

Data Acquisition

The Leica ADS40 Airborne Digital Sensor was used for 100% of the data acquisition. The ADS40 delivered all digital data for the state. The sensor’s construction allows for the simultaneous acquisition of seven bands of information. The ADS40 is a “push broom” style line-scanner that captures pictures along a scan line looking forwards, downwards and backwards from the aircraft.

The ADS40 simultaneously captured black and white, natural color, and color- Infrared data. It produced high-quality digital surface models with reduced ground control requirements, and with coregistration of all the data sets. For more information see acquisition vendor EarthData and Leica.

Coverage

Coverage included the entire state of Indiana (36,602 square miles, more or less) with a 1,000- foot buffer outside the state boundary. Along rivers separating the Illinois and Kentucky borders, the buffer was 1,000 feet or to the opposite bank, whichever distance was greater. Data were acquired during leaf-off conditions, snow-free, with less than 5% cloud cover. Adjacent flight lines overlapped by a minimum of 30 percent. The imagery was acquired with 60 to 80% side-lap over downtown areas in Indianapolis and Fort Wayne in order to produce �true� orthoimagery in which building lean was been eliminated.

Control

A combination of targeted and photo-identifiable ground control and airborne GPS (AGPS) were used to acquire controlled imagery. Nearly 500 control targets were used to support the aerial photography mission. All ground control were tied to the Indiana High Accuracy Reference Network (HARN) and were established by surveyors licensed in the State of Indiana.

Project survey crews can survey 50-quality assurance/quality control (QA/QC) checkpoints dispersed throughout the state. These points were used for QA/QC of the aerial triangulation and orthorectification. These station locations were provided to photogrammetrists who located them from the photography and compared them with the GPS derived locations. Project survey crews also surveyed an additional 100 photo-identifiable QA/QC blind check points dispersed throughout the state that were provided to the State for external QA/QC. All control data and information were provided as part of the final deliverable products.

Metadata

Indiana received Federal Geographic Data Committee (FGDC) standard metadata, including a separate metadata file for each individual county coverage. The FGDC specification used was Content Standard for Digital Geospatial Metadata Version 2 (FGDC-STD-001-1998).