In many application areas (e.g. interior design, furniture retailing or renovation), communication with a customer or future user during the planning and design phase is crucial to select the right products and configurations. Making this communication process effective saves costs, avoids later modifications, and results in providing tailored solutions and higher customer satisfaction. AR has the potential to make these communication processes highly effective and provide a better experience for the customer. However, this content needs to be created by experts from the respective domains, who often lack IT and media skills, and shall provide a lightweight AR experience for the customer. Current AR authoring solutions are quite complex and require manually creating scenes or rely on objects prepared with even more complex applications (e.g. CAD). ATLANTIS will fill this gap in authoring AR experiences by creating a faithful textured geometric (3D) representation from images of the real scene and identifying and segmenting objects in the scene and associating them with the 3D representation. The ATLANTIS authoring tool will enable the fusion of 3D CG elements with real scenes in a guided manner using artificial intelligence (AI) to facilitate more productive and effective content creation. This allows automatic alignment of inserted objects and automated layout generation, enabling the user to interact with different options without the need to manually author each of them. In addition, ATLANTIS will innovate beyond traditional AR authoring by complementing its traditional AR authoring capacity with Diminished Reality (DR) authoring capabilities, enabling the removal and replacement of real objects in the scene allowing to visualise also heavy changes to an environment. The innovations of ATLANTIS will be integrated in an existing solution for interior design and retailing, and validated with professionals and customers.