Senin, 19 Januari 2009

National Agriculture Imagery Program (NAIP) Best Practice Report

A couple of days ago I stumbled across a report put together by ITT for the USDA's APFO group outlining suggestions for improving NAIP image quality. If you're interested in the radiometric processing of aerial photography, this is a must-read. The document outlines image collection guidelines (e.g. optimal flying conditions), the assessment of imagery quality, and image processing recommendations. Some of the material (e.g. orthorectification) is relatively high-level, but the sections on radiometry are great. Also be sure to check out the end of the document, which features a set of screen captures depicting radiometric problems and solutions (pre and post-processing) for image noise, sharpness, clipping, contrast, saturation, and color channel registration.

One thing to note is that NAIP imagery is generally available to the public. Aside from the USDA/NRCS Geospatial Data Gateway, it is also accessible from a number of regional/state-level organizations. A great resource for free orthophotos, NAIP and otherwise, is the World Wind Central section on the topic.

For some practical advice see Jarlath 's recent post (and particularly the video) on the methodology and benefits of using the Vermont 2008 NAIP imagery in a GIS.
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