Combining Street View and Aerial Images to Create Photo-Realistic 3D City Models

Abstract: This thesis evaluates two different approaches of using panoramic street view images for creating more photo-realistic 3D city models comparing to 3D city models based on only aerial images. The thesis work has been carried out at Blom Sweden AB with the use of their software and data. The main purpose of this thesis work has been to investigate if street view images can aid in creating more photo-realistic 3D city models on street level through an automatic or semi-automatic approach. Two different approaches have been investigated in this thesis work: using the street view images for texturing already generated 3D building models and using the street view images directly for reconstructing 3D city models. Data was collected over the study area of KTH, Stockholm, Sweden and the models were created with the two software TerraPhoto, used for texturing, and Smart3DCapture, used for reconstruction. The created models were analyzed and compared with the models based on only aerial images and the two approaches were compared to each other. Through using also street view images when creating city models the models are shown to become more photo-realistic representations on street level compared to the models based on only aerial images. The two tested approaches create very different 3D city models in terms of what is visible in the final model, a textured buildings model or a fully reconstructed environment, and also contains different amount of involved manual work. The textured models contain only the buildings and tend to look very flat because the street images are being projected onto flat building walls whereas the reconstructed models reconstructs everything being visible in the images, trees, cars etc., and create a full scale 3D city model. There are however limitations associated with using street view images when modeling cities since they only contain information on the ground level and no information about roofs or higher parts of the city environment and the street view images therefore need to be used in combination with aerial images. Using the street view images for reconstructing city models showed some complications in terms of wavy facades, bumpy roads and objects such as trees being inaccurately modeled. The texturing approach creates less visually pleasing models since objects such as trees and lighting poles are being projected onto the facades. The models based on aerial images look more visually appealing compared to when also using the street view images but lack the resolution be considered as photo-realistic on street level. This thesis work has shown that there is potential in using street view images when creating photo-realistic 3D city models on street level even though it is not yet a semi-automatic or automatic approach.