Adjustment Models and Methods of Parcel Area Processing in GIS

In this paper,area processing for cadastral parcel in GIS is thoroughly studied.The principles and models of area adjustment are presented.Then three themes of area processing are proposed:the first is that the area of a parcel is treated as a fixed value and the digitized coordinates are regarded as observations;the second is that both area and coordinates are treated observations,which are two different kinds of observations.It is important to determine the weights between these two kinds of observations.Therefore,the variance component estimation with parameters based on the condition adjustment is then used to solve this problem;the third is that the scale error in area adjustment is considered.The reason is that in the parcel area digitization,the systematic error has great effect on the parcel area due to errors in transformation between different coordinates systems and image correction.And the variance component estimation with parameters based on the condition adjustment is then presented,the hypothesis tests are further conducted to determine the obviousness of area scale error.In the end,case studies of the three themes are given,the results are discussed and the conclusions are reached that it is necessary to select a pertinent model to process parcel area to improve the accuracy parcel digitization in GIS.