###### Abstract
Key steps in such workflows include data collection (laser scans, photogrammetry, or other survey methods) and processing (3D format compatible with BIM software), BIM modelling (based on 3D processed data) of the building and of certain structural elements and architectural details (walls, floors, windows, doors, decorations, etc.) [16], the inclusion of historical documents and previous reports, and finally, the assigning of the investigation data to the BIM elements (concerning materials, surfaces, etc.). The modelling of a building and building elements is usually restricted to a low LOD (level of detail), making the representation of historical buildings or damaged buildings (ruins) that have complex structures quite difficult. In this paper, we introduce a new way of documenting, managing, and disseminating heritage buildings' multimodal imaging data in an interactive online medium. The concept stems from the need to attribute imaging data from different sensors to realistic digitized building elements, accessible in an open, interactive online environment. Although similar approaches based on 3D photogrammetric or scanned models have been reported [17], the presented workflow and product simplify the multimodal imaging integration method and add to the realism of the presented 3D data. To test this concept, a prototype web application was developed, which is able to manage all of the available data for a 3D digitized building while featuring a custom 3D viewer, interchangeable referenced imaging data, and other 3D-viewer-specific tools and features. The web platform was developed using a minimal framework with a Model-View-Controller (MVC) architecture (like Codelgniter4), which makes the application compatible with different database management systems and WebGL libraries (Three.js) for the 3D viewer. This paper covers not only the development process but also a typical workflow using this web application in a particular case study involving a 17 th-century church. The contents of the web platform, although it is a prototype, are freely accessible following the principles of the open-access policy for the democratization of research results. It is accessible at this address: [[http://3d-vimm.lutthonium.com/](http://3d-vimm.lutthonium.com/)]([http://3d-vimm.lutthonium.com/](http://3d-vimm.lutthonium.com/)) (accessed on 30 October 2023). Before describing the web application development process and workflow, although it might seem trivial, the terms and meanings of a 3D model and multimodal imaging will be briefly described. A 3D model is a term used for a digital format that embodies multiple elements that can be interpreted and rendered in a 3D virtual environment. It is often confused with a 3D mesh model. A 3D model can contain multiple meshes, lights, materials, and even animation data. A 3D mesh model refers to the geometric structure of a specific object and is composed of vertices (points in 3D space), edges (segments that connect the vertices), and polygons (or faces, formed by the edges). A 3D model can also be reduced to a single 3D mesh but can also represent an entire scene with multiple objects. The file formats for these 3D data are the same in either case. The proposed concept is based on this aspect, as the digitized buildings will be split into multiple sub-objects but stored on the disk as a singular 3D model. The concept of multimodal imaging, or multimodality imaging, is not new [18, 19]. In medicine, it has been used for decades in relation to the integration of two or more distinct imaging methods to capture different types of information for the same subject [20]. Today, multimodal imaging is pivotal in all areas of research, like neuroscience, the environment, or military and security applications. In heritage science, in conservation and restoration projects, a complete characterization of a cultural heritage asset is necessary to understand the current state of conservation and to be able to propose a proper conservation plan [21].