Two aerial photogrammetric methods for measuring small irregular areas

Authors: M. McGreevy
Publication: New Zealand Journal of Forestry, Volume N.Z.J.For. 1974, Issue N.Z.J.For. 19(2) 1974, pp 290-294, Aug 1974
Publisher: New Zealand Institute of Forestry

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Abstract: Eleven areas of deep ripping in eleven separate compartments of Kaingaroa Forest were measured using a chain and compass traverse. These measurements were compared with estimates of the eleven areas derived from 1:21 OOO scale vertical aerial panchromatic negatives measured with a dot grid having 7.6 dots per square millimetre. The comparison included results from two independent interpreters using two methods of scaling. One method involved direct scaling while the other involved scaling from maps (1:63 360) scale and existing large format photographs. The mean difference between the photogrammetric and field measurements varied from 1.7 to 6.7% of the mean field measurement and were not found to be statistically significant. The 90% confidence interval of the differences fell within ±10%) of the field mean for all cases investigated. The photographic method was estimated to be much less expensive than field methods when large numbers of areas are involved.

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