2.1 1” GSD: One-inch (1”) Ground sampling distance (GSD) ortho and 3-band natural color 4- directional oblique imagery (40-45 degree angle) in 20 (twenty) specified one square mile sections of Johnson County (see Appendix – yellow highlighted sections); and, 2.2 3” GSD: Three-inch (3”) GSD, ortho and 3-band natural color 4-directional oblique imagery (40-45 degree angle) in the remaining one square mile section of Johnson County. (see Appendix A – all unhighlighted sections) 2.3 Flight Specifications: Imagery shall be captured between the months of November 2024- Janurary 2025. The Contractor shall re-fly, at no additional cost to the County, any unacceptable aerial photography, with the re-flight coverage overlapping the accepted photography. a. 0.5' GSD: This means each pixel in the orthophoto represents 0.5 feet on the ground. The smaller the GSD, the higher the resolution, so this is a relatively high-resolution image. b. 30-degree sun angle: This refers to the angle of the sun above the horizon at the time of image capture. A 30-degree sun angle helps reduce shadows that might obscure details in the image, providing better visibility of the ground. c. Cloud and cloud shadow-free: The imagery must be free of clouds and any shadows cast by clouds, ensuring that all ground features are clearly visible. d. ± 1-foot horizontal accuracy: This indicates the positional accuracy of the imagery. The horizontal location of features should be accurate to within 1 foot, which is a high level of precision. e. Clear ground conditions following leaf-off: The imagery should be captured when trees have lost their leaves (leaf-off condition of 30% or less foliage coverage), improving visibility of the ground and structures. f. No snow or flooding: The imagery must be captured under conditions without snow cover or flooding, so the actual surface of the ground can be clearly seen. 2.4 Imagery Access: Early access delivery will be made available to users as imagery is captured. 2.5 Mosaic Images: The ortho imagery should also be delivered in a hardcopy countywide mosaic(s). Mosaic(s) will combine all the geographic area’s tiled images into a MrSID format. The hard copy orthomosaic will remain in procession of Johnson County if the county decides not to continue annual subscription licensing outside of length terms provided in agreement. Surrounding County Images: The selected vendor must be able to provide the surrounding counties (Jackson, Lafayette, Saline, Pettis, Henry, and Cass) oblique imagery, if available, to Johnson County in one software platform.
