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High resolution DEMs for urban applications

The authors demonstrate that digitally-scanned 1:40,000-scale NAPP aerial photography, used in conjunction with precision ground control, can be used to generate DEMs with horizontal resolutions of 1-3 m. The vertical accuracies of the DEMs were evaluated using more than 50,000 check points derived from a precision kinematic GPS survey. The results indicate the DEMs have RMS vertical accuracies on the order of 1.8-2.5 m. The DEMs are shown to reveal very fine-scale features in an urban test area. The horizontal resolution and vertical accuracy of the NAPP DEMs are many times better than those currently derived from satellite remote sensing platforms. Moreover, the NAPP imagery are an inexpensive source of data that are readily available throughout most of the United States.