But this kind of entity may insurmountably have some uncertainties when it is expressed abstractly to the spatial object of gis, and these uncertainties are the uncertain factors including error, inaccuracy, illegibility and so on 但是这类实体在抽象描述为gis的空间目标时难以避免地会带有一定程度的不确定性,这种不确定性指的是在进行抽象描述时随之产生的误差、不精确性、模糊性和含混性等不确定性因素。