One of the common problems of modern geoinformation libraries and interfaces when constructing spatial isolines is the presence of multiple artifacts in the resulting set, in particular, open level lines. As a result, the formed set of spatial isolines after the web rendering procedure makes it difficult to analyze the spatial distribution of the corresponding parameters, on the one hand, and reduces the quality of spatial image rendering, on the other. At the same time, artifacts of spatial isolines are especially critical for large amounts of data. The paper proposes an approach that makes it possible to correct software-generated isolines by identifying open lines and their subsequent selective connection. From the point of view of software implementation, the presented approach practically does not change the response time of server scripts. The effectiveness of the developed approach is confirmed by the example of a web application that provides visualization in the form of a set of spatial isolines of geophysical parameters in the auroral oval region.