CAJ | 학술논문

为了研究QuickBird影像提取切沟形态参数的精度，该文选取陕北黄土区吴起县合沟与绥德县桥沟小流域，分别利用同时相的三维激光扫描全站仪和 QuickBird 影像数据源提取切沟形态参数，分析 QuickBird 影像提取切沟形态参数的精度，探究误差产生原因。研究结果表明：与三维激光扫描全站仪相比，QuickBird 影像目视解译合沟和桥沟小流域切沟面积、周长的平均相对误差都在5%左右；沟缘线边界偏差大于0.6 m（相当于QuickBird影像的一个像元值）的面积百分比的均值都能控制在4%以内；2个小流域中沟长的平均相对误差分别在2%和5%左右，沟长的平均绝对误差分别在0.5和0.75 m左右；目视解译面积、沟长的平均相对误差、最大相对误差、不同解译人员的最大误差与参数值之间都具有显著地负相关，即切沟越大，误差越小；沟缘线附近的植被类型影响目视解译精度，与灌草植被覆盖的小流域相比，草本覆盖的小流域中切沟参数的解译精度更高。总体上来看， QuickBird影像为小流域尺度上监测切沟发育提供了便捷、可靠地数据源。
위료연구QuickBird영상제취절구형태삼수적정도，해문선취협북황토구오기현합구여수덕현교구소류역，분별이용동시상적삼유격광소묘전참의화 QuickBird 영상수거원제취절구형태삼수，분석 QuickBird 영상제취절구형태삼수적정도，탐구오차산생원인。연구결과표명：여삼유격광소묘전참의상비，QuickBird 영상목시해역합구화교구소류역절구면적、주장적평균상대오차도재5%좌우；구연선변계편차대우0.6 m（상당우QuickBird영상적일개상원치）적면적백분비적균치도능공제재4%이내；2개소류역중구장적평균상대오차분별재2%화5%좌우，구장적평균절대오차분별재0.5화0.75 m좌우；목시해역면적、구장적평균상대오차、최대상대오차、불동해역인원적최대오차여삼수치지간도구유현저지부상관，즉절구월대，오차월소；구연선부근적식피류형영향목시해역정도，여관초식피복개적소류역상비，초본복개적소류역중절구삼수적해역정도경고。총체상래간， QuickBird영상위소류역척도상감측절구발육제공료편첩、가고지수거원。
High-resolution satellite images such as those from Ikonos and QuickBird are increasingly available and are considered a valuable tool for extracting the consequences of gully erosion, and QuickBird imagery has been used to map gully features. To evaluate the accuracy of extracting morphological parameters of bank gullies including area, perimeter, and length from QuickBird imagery bymanual visual interpretation, and to analyze the causes of errors, 20 bank gullies were selected in Hegou catchment and Qiaogou catchment located in the Loess Plateau of northern Shaanxi province, respectively. 3D laser scanner was used to measure the topography of bank gullies within two weeks after the QuickBird images were taken. The interval among measurement points of 3D laser scanner was set as 0.15 m. 3D laser scanner had been increasingly used to measure the topography as it can provide a high accuracy, non-contacted, penetrating and rapid method that enables the rapid production of accurate, high-resolution digital elevation model (DEM). Based on Delaunay triangulated irregular networks (TIN), then DEM with the pixel size of 0.15 m × 0.15 m was created using the 3D Analyst extension of ArcGIS 9.3. On this basis, the values of morphological parameters extracted from DEM were taken as actual values and errors of morphological parameters of bank gullies extracted from QuickBird imagery were determined. The average absolute error, maximum absolute error, average relative error, maximum relative error, and maximum relative error among different interpretation persons were used to assess the accuracy of manual visual interpretation of QuickBird imagery. The results showed that maximum relative error of area and perimeter ranged from 4.1% to 22.2% and 1.4% to 22.2% in Hegou catchment, respectively, while maximum relative error ranged from 2.4% to 22.6% for area and 4.5% to 29.7% for perimeter in Qiaogou catchment, respectively. Although maximum relative error appeared to be large for some gullies, average relative error of area and perimeter were both about 5% in two study areas. In addition, by overlaying the two valley regions extracted from QuickBird imagery and DEM, the area that the distance offsets was larger than 0.6 m (QuickBird image one pixel value) remained below 4%. Average relative errorof gully length in Hegou catchment and Qiaogou catchment were about 2% and 5%, respectively, with corresponding average of the average absolute error of 0.5 m and 0.75 m. Correlation analysis showed that average relative error, maximum relative error and maximum relative error among different interpretation persons were negatively correlated with the area and length of bank gully (P<0.05), which meant that the larger the area and length of bank gully were, the smaller the errors were. This suggested that choosing large gullies would reduce the errors when the morphological parameters were extracted manually from QuickBird imagery. The accuracy of manual visual interpretation was also influenced by the vegetation types near the gully boundary. Catchments which land was covered with native grassland had higher precision than those were covered with shrub and grass. Overall, QuickBird imagery can provide reliable data source for extracting morphological parameters of bank gullies. The results can provide the references for assessing gully erosion using QuickBird imagery at larger spatial scales rather than direct field measurements.