Johnson County GIS Online - Internal Site
An Internet Mapping Application of the Johnson County, Iowa GIS

ORTHOPHOTOGRAPHY (Aerial Photography)

To access the 2006 Orthos

1.Click here
2. Choose "Aerial Photography 2006" from the drop-down list.
3. Enter any search info you may have and click "Get Map" button or simply click "Get Map" (to navigate around the map manually).

Benefits
One of the most important dataset within a GIS is orthophotography. If developed correctly, orthos (short for orthophotography) provide a solid foundation for database development.

2006 Orthos
Johnson County started a project in 2006 to collect new countywide digital orthophotography. The orthos will be accurate within 2 feet. Meaning locations identified on the orthos, will be within 2 feet of the same location measured on the surface of the Earth. The orthos will also be of high resolution. Resolution refers to level of detail visible in an image. The higher the resolution, the more detail that is provided by the image. The 2006 orthos were collected at an altitude of 4800 feet and processed to a pixel size of .5 feet. A pixel is an individual cell within the image. A smaller pixel size increases the size of the database, but assists in providing higher resolution orthophotos.

Digital imagery in which distortion from the camera angle and topography have been removed, thus equalizing the distances represented on the image.

The entire dataset of 2006 orthos are now available countywide.

Future orthophotography projects are currently being planned.

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