利用数字摄影测量探测橡树草原变化

Monitoring Oak Woodland Change Using Digital Photogram metry

数字摄影测量的一个新的应用，即自然景观的变化监测，它是我们近年围绕遥感生态测量学所做的一些初步尝试。用加州橡树草原区１９７０ 年和１９９５ 年１∶１２ ，０００ 比例尺航空摄影立体像对，构建有别于数字地形模型的数字表面模型。由于数字表面模型上记录着树冠和其它景观的三维表面坐标，我们可以测量树高与树冠郁闭度，从而比较２５ 年间橡树草原的变化。用数字表面模型有助于改善遥感多光谱分析所探测到变化的精度，使融合三维表面数据和多光谱数据以提高遥感信息提取的精度成为可能。

Inthis paper we report a new application of digital photogrammetry.Itreflects ourrecentattempttoward the developmentofthe field of photo ecometrics. We illustrate the potential of digital photogrammetry in the monitoring of changes ofoak woodland of California using 1∶12 ,000 scanned aerial photographs.The photographs were taken in 1970 and 1995 .Stereopairsin 1970 and 1995 have been usedto derive digitalsurface models(DSM) thatcontain 3Dmorpho logicalcoordinates of everylandscape componentincluding oak wood ,grassland and buildings.The DSMs allow us not only to studychanges ofcanopy closure butalsoto measuretree heightsand heightchange duringthe25 yearperiod .The potentialof DSMopens many opportunities for improving the accuracy of change detection and species recognition than solely usingtraditional multispectral analysis.