基本农田规划图斑A中线形地物面积的计算：
先把线形地物图层B，clip到基本农田图斑内，得到C，然后根据切割后和切割前的长度比分摊线性地物面积。再用基本农田的图层identity C图层，得到D，使得线性地物具有了基本农田图斑的编号。
这里要注意，在两个图斑交界处的线性地物会被分成两个，形成两条记录，分别含有由这两个图斑的TBBH（图斑编号），这时重新计算一下shape—length，然后导出到Excel中观察长度相等的记录，会发现有一部分计数为2，他们就是处于图斑交界处的线性地物了。
保存这个Excel，然后join到D图层，将计数为2的记录的线形地物面积除以2。
此时的D图层用TBBH（图斑编号）或唯一标识码进行统计，将统计后的Excel D与A图层join，把Excel D中的线性地物面积赋给A，再计算基本农田的净面积就可以了。（注，图斑中用的是平面面积）
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.