TOWARDS LARGE-SCALE BUILDING ATTRIBUTE MAPPING USING CROWDSOURCED IMAGES: SCENE TEXT RECOGNITION ON FLICKR AND PROBLEMS TO BE SOLVED - Sun, Y.; Kruspe, A.; Meng, L.; Tian, Y.; Hoffmann, E. J.; Auer, S.; Zhu, X. X. (Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci., 2023)