The Imagery
The 2006 National Agriculture Imagery Program (NAIP) imagery was collected using a film based aerial mapping camera. Aerial photography was collected at a scale of 1:40,000 and images were spotted at the center of US Geological Survey quarter-quadrangles. Stereo imagery was collected so there were also images spotted at the south and north quarter-quad boundaries.

Surdex was the vendor for the Washington State project and they were contracted to rescan the aerial negatives in order to produce a higher resolution orthophoto than the Farm Services Agency (FSA) standard (one or two meters). Aerial negatives were rescanned at 10 microns in order to produce the 18-inch pixel resolution required by state of Washington partnering organizations.

Photogrammetric aero-triangulation was performed to control the imagery and produce orthophotos. Imagery was color balanced and delivered to the Washington State Department of Natural Resources (DNR) as approximately 14,000 separate tiles, each 8,192 by 8,192 pixels in a geo-tiff format. This tile size was selected because it is an even power of two (2 to the 13th power), so any pyramiding or re-sampling would use full pixels.

DNR processed several data sets (various projections, formats and resolutions) to meet the various needs of the 60 partnering organizations that funded the project. This included the image data set that resides at the Washington State Imagery Portal. The Imagery Portal data is stored natively in Washington State south-zone projection and as an approximate 5 to 1 jpeg compressed data set. The statewide uncompressed geo-tiff orthoimagery is approximately 3.2 terabytes in size, while the compressed data set that resides at the Portal is approximately 700 gigabytes. Image overviews were created using ESRI Imager Server software, plus these images were cached to provide more rapid access to the user.