What is the source of the images and the original resolution?
The majority of the images are based on the “National Agricultural Imagery Program (NAIP) Digital Ortho-rectified Images (DOQ) and where taken the US Department of Agricultures Farm Services Agency, Aerial Photography Field Office. The original images were taken from approximately 20,000 feet and the majority are 1M resolution (Iowa and parts of St. Louis County in Minnesota around Ely are 2M resolution). The images in the Twin Cities area were from the US Urban Imaging program and are 2 foot resolution. The images are further processed by combining them with USGS contour information for accurate shading to give a 3D effect and then correcting the anomalies that are common in most aerial photos (visible merge lines, tonal differences, water sun “glint”, etc.). Finally depth information is superimposed on the image displayed as shaded contour lines to give a 3D effect to match the rest of the image.
