Feature/ground height-based colored image generating apparatus and feature height-based colored image generating program

A non-transitory recording medium storing a feature height-based colored image generating program causing a computer to execute operations including:

• storing a digital elevation model (DEM) of an area in a digital elevation model storing memory;
• storing a digital surface model (DSM) of the area in a digital surface model storing memory;
• generating a DHM, which is a difference between the digital elevation model (DEM) and the digital surface model (DSM), in a DHM storing memory;
• deriving an inclination per mesh of the DHM and generating an inclination image in which a grayscale value corresponding to the inclination is allocated to the mesh;
• decreasing an elevation value allocated to each mesh of the digital surface model (DSM) certain times per mesh, setting each mesh as a focused point, defining a certain range per focused point, and deriving an aboveground opening, an underground opening, and an inclination, to generate in a first red relief image storing memory a first red relief image in which a brighter color is allocated to a part having a higher aboveground opening, in which a darker color is allocated to a part having a higher underground opening, and in which a red-emphasized color is allocated to a part having a higher inclination;
• increasing an elevation value allocated to each mesh of the digital elevation model (DEM) predetermined times per mesh, setting each mesh as a focused point, defining a certain range per focused point, and deriving an aboveground opening, an underground opening, and an inclination, to generate in a second red relief image storing memory a second red relief image in which a brighter color is allocated to a part having a higher aboveground opening, in which a darker color is allocated to a part having a higher underground opening, and in which a red-emphasized color is allocated to a part having a higher inclination;
• reading per mesh of the DHM a height of a feature allocated to the mesh and generating in a relative height gradient-tinted image storing memory a relative height gradient-tinted image in which a color value is allocated to the mesh in accordance with the height of the feature;
• generating in a feature height comparison image storing memory a feature height comparison image in which the inclination image and the relative height gradient-tinted image are overlaid on each other;
• generating in a feature height-based colored image storing memory a feature height-based colored image in which the first red relief image and the feature height comparison image are overlaid on each other;
• and
• synthesizing the feature height comparison image with the second red relief image to generate a feature height comparison image, in which each mesh is expressed in color in accordance with a height and an inclination of the mesh, in a feature height comparison image storing memory.