Techniques and systems for gradient search are provided based on sensing or measuring at selected locations of a target object without performing full-field sensing or measuring over the entire field of the target object. Search methods are provided to include determining a coordinate of a boundary of a region in relation to a loop in a proximity of a first location, determining a direction of a gradient of the coordinate corresponding to the first location, and selecting a second location based on the determined direction. A search system can be implemented to include an imaging system to determine a coordinate of a feature of an object on a loop in a proximity of a first location, and a controller, coupled to the imaging system, to determine a direction of a gradient of the coordinate corresponding to the first location, and to select a second location based on the determined direction.本發明揭示一種根據在目標物體的所選位置上感測或測量以進行梯度檢索,而不用在整個目標物體上執行完整感測或測量之技術及系統。本說明書提供多種檢索方法,包括決定與第一位置附近的環形相關的區域邊界之座標;決定對應至該第一位置的該座標之梯度的方向;以及根據該決定的該梯度的方向選擇第二位置。一檢索系統可實施為包括一成像系統,決定第一位置附近的環形上一物體元件的座標,以及包括一控制器,耦合至該成像系統,用於決定對應至該第一位置的該座標之梯度的方向,該控制器更用以根據該決定的梯度的方向選擇第二位置。100...整合梯度檢索與局部成像方法流程圖110、120、130...流程步驟
