Geospatial information system (GIS) is widely used in military sides. As an example, penetration analysis is typical for GIS using in military side. In this paper, we apply GIS to analyze the optimized detector location. We use the thermal observation device (TOD), and select Daejeon city to perform this analysis. In this paper, we use DEM data and VITD data. We bring genetic algorithm in our procedure to fine a more effective and global solution. The locations of the rectangular coordinate point (i.e., x and y pixel coordinate) of TOD will be a gene, and a group of TOD locations will be a chromosome. We select the uniform crossover method to make next generation. Target function is composed with detected pixel number part and detection probability part. The research goal of this study is to find the location with the highest target function value. Result of the experiments provide optimized TOD placement.