ITU‐T's Technical Reports and Specifications 659 Figure 4 – Direct and indirect objects of IMSSC 2.2 Challenges of IMSSC In cities nowadays, information resources, like sensors, observations and models, are featured as different sources, great varieties, and huge numbers. However, when responding to the emergency events, many problems still exist, including: (1) the encoding formats of the information resources are various, difficult to be integrated; (2) the fusion workflow between information resources is not unified, resulting in the non‐uniform fusion results, inconsistent accuracy, and difficulty in fusion processing; (3) the inconformity of the information resources and their fusion results service interfaces cause trouble in their publishing, sharing, discovering, and accessing [b‐Toppeta]. All problems described above pose significant challenges to urban development and to IMSSC. To be specific, the challenges faced by IMSSC can be illustrated from three perspectives: 1) Information resources come from various sources and heterogeneous systems. It is difficult to interconnect such systems for data sharing. Consequently, this leads to difficulties in multi‐level collaborative decision‐making. Taking sensors as examples, there are space borne platforms (hundreds of orbiting satellites), airborne platforms (thousands of UAVs, airships and balloons, etc.) and ground platforms (millions of ground sensors). However, there is no unified meta‐model to represent and manage the huge amounts of