Data update is an important task for GIS.However

complex and inefficient process has been a principal problem that gets in the way of updating GIS data in time during vector data update in GIS

it is necessary to substitute an automatic method for manual method currently.In order to make data update less dependent on arbitrary judgement

auxiliary information should be cited.During the change detection of remote sensing images

GIS data have played an important role as prior knowledge in increasing accuracy and simplifying process.Approaches of change detection and data update has been proposed in recent years.However

those approaches are based on neural network

knowledge base instead on linear vector data.Linear vectors that describe the object region edge in GIS

is usually irregular polygon which is represented as connection of the discrete points on the edge.Hence

it makes sense that the method depending on the attributes of linear vectors above is figured out to update the coordinate values of points on the boundary.A simple and convenient method

which utilizes data in GIS as prior knowledge

is proposed here for vector edge update to solve the problem of complexity and inefficiency.This method involves three-step processes of searching edge: generally locating points

recognizing the convexity and concavity

and detailedly describing the polygonal shape.The points moves within the limited regions that threshold values determines.This method integrates remote sensing images and prior GIS data

as well as replace searching edge curve with locating inflexions to simplify change detection and update process.In addition

the method points out an idea of integration of remote sensing and geographical information system data with the carrier of linear vectors.With the experimental data of Landsat TM remote sensing images and the prior knowledge of vector data saved as shapefile of ArcGIS software

the method is applied to detect and update the edges of Keqin Lake

Dongsheng Reservoir and an area of marsh in Zhalong Wetland in Heilongjiang Province

China.And then update accuracies are tested by the simplified buffer detection algorithm for computing polygonal error based on original buffer detection algorithm

and the polygonal comparability between this presented method and the manual method is calculated and analyzed.In terms of the characteristic of polygon

five factors are adopted in evaluating the polygonal comparability: major direction angle and minor direction angle of minimum exterior rectangle

length and width of minimum exterior rectangle

and polygonal perimeter.Relative error of these five factors are computed

based on which mean value is considered as evaluation of polygonal comparable percentage.Besides

different from original buffer detection algorithm

a simplified buffer detection algorithm is pointed out.Based on the improvement

buffer detection algorithm can be calculated through infinite numbers of points on the polygon that stand for object region edge.Estimations are obtained according to those two criteria above.The results show that the update accuracy of proposed method reach above 80%

a little lower than the result derived from manual method

though good polygonal comparability very close to the result of manual method.In spite of that

the approach presented performs an automatic procedure of vector edge update in GIS.Apparently

this method well simplifies change detection and update process

as well as achieves an update accuracy close to the manual method

and a relatively satisfactory comparability with the manual update method.Besides

the results implies that different experimental objects lead to distinct evaluated results.The simpler the shape of edge is

the better the method is evaluated.Thus

the result from experiment on Keqin Lake is better than Dongsheng Reservoir and marsh

as the contour of Keqin Lake is simpler than that of the other two.Nevertheless

there are still several disadvantages to be improved.This method loses control of contour shape of object so that the movement can not be restricted to be harmonious between adjacent points.Also

the moving range threshold of points are supposed to be settled by researcher

which means that the automatic process is affected by human idea.