线元点位误差带的“纺锤形”模型

对当前GIS界流行的以点位误差描述线元位置不确定性的误差带理论提出相反的观点。最早提出的线元误差带理论为"ε-带"模型,后来又提出了"E-带"模型和在其基础上发展的"G-带"模型。后两者均认为以控制点点位误差描述的线元的误差带的基本形状呈"哑铃"形,即认为线元上端点的位置不确定性大于端点之间的点的位置不确定性。笔者的看法与此相反,笔者认为线元上两控制点之间的点的位置不确定性应大于控制点的位置不确定性,且在两控制点的中间达到最大,即线元误差带的基本形状应为"纺锤形"而不是"哑铃形"。

"Spindle-shape" model about point position error in line element

This paper proposes an oppositional opinion to a popularly acceptedissue in GIS community about error-band of line element position uncertainty.The earliest proposed line element error band theory is “ε-band” model,then “E-band” model was proposed and developed to “G-band” model.The latter two all reckon that basic shape of line element error band based on control points error is “dumbbell-shape”,i.e.error in control end points is larger than points error between two control points.The authors view is opposite,i.e.the position uncertainty of points between two control points should be larger than two control points,reaching the largest in the middle of two control points,i.e.the basic shape of line element error band is “spindle-shape” other than “dumbbell-shape”.