基本農田規劃圖斑A中線形地物面積的計算：
先把線形地物圖層B，clip到基本農田圖斑內，得到C，然後根據切割後和切割前的長度比分攤線性地物面積。再用基本農田的圖層identity C圖層，得到D，使得線性地物具有了基本農田圖斑的編號。
這裏要注意，在兩個圖斑交界處的線性地物會被分成兩個，形成兩條記錄，分別含有由這兩個圖斑的TBBH（圖斑編號），這時重新計算一下shape—length，然後導出到Excel中觀察長度相等的記錄，會發現有一部分計數爲2，他們就是處於圖斑交界處的線性地物了。
保存這個Excel，然後join到D圖層，將計數爲2的記錄的線形地物面積除以2。
此時的D圖層用TBBH（圖斑編號）或唯一標識碼進行統計，將統計後的Excel D與A圖層join，把Excel D中的線性地物面積賦給A，再計算基本農田的淨面積就可以了。（注，圖斑中用的是平面面積）
Purearea calculation: Parcel is the basicpolygon unit in the planning. Usually, there are some linear or punctuateground object (which is too small to be drawn on the map) in the parcel. Thus,two kinds of different area namely gross area and pure area come into being.The gross area (Garea) is the polygon area on the map that can be calculateddirectly. The pure area need to be calculated by (1). Areal denotes the area oflinear object; length l is in the attribute table of layer “JQXZDW” (linearground object of the base year). Area pot denotes the area of punctuate object.Segmentation of parcel is inevitable in the planning. The pure area of a parcelwill change after the partition and recalculation. As Fig.4 shows, linearobject L (belongs to layer L) passes through parcel P and point object Q(belongs to layer Q) is embodied by P (belongs to layer P). Under thiscircumstance, line L is separated into a and b. Area a is calculated by (2), sois Area b.
Areap = Areag-Areal-Areapot (1)
Areaa = lengtha / lengthl × Areal (2)
However, if the linear object locates on the commonboundary of several parcels, the complexity level of calculation will upgrade.The database contains the function for dealing with this problem. Under thiscircumstance, the linear ground object will be clipped into several parts byparcels. Shared parts between each two contiguous parcels are copied and caninherit the attributes of thetwo parcels based on their spatial relationship.To each parcel, the area of copied linear features should be divided by 2 whenpure area recalculation occurs.