TY - JOUR A1 - D’Hauwers, R. A1 - Walravens, N. A1 - Ballon, P. T1 - FROM AN INSIDE-IN TOWARDS AN OUTSIDE-OUT URBAN DIGITAL TWIN: BUSINESS MODELS AND IMPLEMENTATION CHALLENGES JO - ISPRS Ann. Photogramm. Remote Sens. Spatial Inf. Sci. J1 - ISPRS-Annals VL - VIII-4/W1-2021 SP - 25 EP - 32 Y1 - 2021/09/03 PB - Copernicus Publications SN - 2194-9050 UR - https://isprs-annals.copernicus.org/articles/VIII-4-W1-2021/25/2021/ L1 - https://isprs-annals.copernicus.org/articles/VIII-4-W1-2021/25/2021/isprs-annals-VIII-4-W1-2021-25-2021.pdf DO - 10.5194/isprs-annals-VIII-4-W1-2021-25-2021 ER -