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首页> 外文期刊>Australian Journal of Botany >Effect of photoscale, interpreter bias and land type on woody crown-cover estimates from aerial photography.
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Effect of photoscale, interpreter bias and land type on woody crown-cover estimates from aerial photography.

机译：照相比例尺，解释器偏差和土地类型对航空摄影中木冠覆盖估计的影响。

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摘要

Woody vegetation cover interpreted from aerial photography requires assessment against field data as the signature of woody vegetation cover may differ between photoscales, vegetation types and photo-interpreters. Measurements of aerial woody cover taken from aerial photography of four different photoscales were compared with a field dataset from Eucalyptus- and Acacia-dominated landscapes of semi-arid Queensland. Two interpreters employed a method that utilises a stereoscope and sample-point graticule for manual quantified measurements of aerial woody cover. Both interpreters generated highly significant models accounting for 77 and 78% of deviance. Photoscale appears to have a consistent effect whereby the signature of woody cover increases as the photoscale decreases from 1:25 000 to 1:80 000, although the magnitude of this effect was different between interpreters. The results suggest no substantial differences in the shape of models predicting crown cover between Acacia- and Eucalyptus-dominated land types, although the precision of the models was greater for the Acacia (90-91% of residual deviance) than for the Eucalyptus (50-56% of residual deviance) land type. The reduced accuracy in the Eucalyptus land type probably reflects the relatively diffuse crowns of the dominant trees. The models generated for this dataset are within the range of those from other calibration studies employing photography of a range of scales and methodologies. The effect of photoscale is verified between the available studies, but there may also be variations arising from methodological differences or image properties. The present study highlights the influence of photoscale and interpreter bias for assessing woody crown cover from aerial photography. Studies that employ aerial photography should carefully consider potential biases and cater for them by calibrating assessments with field measurements..
机译：从航空摄影中解释的木质植被覆盖度需要根据野外数据进行评估，因为木质植被覆盖度的特征可能在光标度，植被类型和照片解释器之间有所不同。将来自四种不同光标的航空摄影中的空中木质覆盖物的测量值与来自半干旱昆士兰州以桉树和金合欢为主的景观的野外数据集进行了比较。两名口译员采用了一种方法，该方法利用立体镜和采样点标线来对空中木质覆盖物进行手动定量测量。两位口译员都产生了非常重要的模型，占偏差的77％和78％。光影效应似乎具有一致的效果，即随着光影比例从1:25 000降低至1:80 000，木质覆盖物的签名也会增加，尽管这种影响的大小在口译人员之间有所不同。结果表明，相思模型和以桉树为主的土地类型之间预测树冠覆盖的模型形状没有实质性差异，尽管相思模型（残余偏差的90-91％）比桉树模型（50）的精度更高-56％的剩余偏差）土地类型。桉树土地类型的精度降低可能反映了优势树的树冠相对分散。为该数据集生成的模型在其他校准研究的模型范围之内，而其他校准研究则采用了一系列比例尺和方法学的照相方法。可用研究之间已验证了光洁度的影响，但方法上的差异或图像特性也可能会产生差异。本研究强调了光度标尺和解释器偏差对评估航空摄影中木质冠冠的影响。进行航空摄影的研究应仔细考虑潜在的偏差，并通过用野外测量来校准评估来解决这些偏差。

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