Visual quality of the ground in 3D models: using color-coded images to blend aerial photos with tiled detail-textures

In interactive 3D-environments of urban-planning projects, the ground materials and land features are often represented by aerial photos. These lack of detail and therefore often look blurred and diffuse. This paper presents a technique to enhance the visual quality of the ground by blending the aerial photos with tiled detail-textures in a level-of-detail integrated system that is controlled by color-coded images. The color-coded images are created by extracting land features such as grass, asphalt, rock and water from the aerial photos or 2D CAD-drawings. The effects of different resolutions of the aerial photo and color-coded image are presented and discussed. To evaluate this approach, the technique was tested on a simple rendering performance scene and on two sub-sets of the 3D-city model of Göteborg, namely a landscape and an urban data set. The visual quality and rendering speed of the 3D model were positive and are presented in several images and table.