SCAN to BIM Beyond a Final BIM: Why, When and How

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Building Information Modeling (BIM) has become a must in architecture when it comes to new buildings, but in heritage buildings and in rehabilitation projects, it is still a debate if it’s useful or efficient to make a BIM model. In this paper we analyze and propose When, How and Why modeling in BIM should be a standard process for rehabilitation projects in which an architectural has been performed. In the field of heritage architecture, archeology and rehabilitation, to create an as-built model to work on, it is needed an architectural survey using a laser scan or/and photogrammetry, which captures dense 3D measurements of the building, so architects can make studies of its geometry, detect pathologies and use it as a base for their new designs. However, even though the 3D surveying technics has evolved in the recent years, in the world architecture, the point clouds are still pretty unknown, therefore for many architects are useless information in that format. So, it is necessary to convert this 3D information as point clouds to a more common file like 2D vector drawings in CAD. For this process, it should be question if and how modeling in BIM from the point cloud (scan to BIM) helps to this purpose, without taking into the account that modeling in BIM you get a BIM model, which in rehabilitation and heritage is still not common enough to work with it. Analyzing the information of the point clouds, the typology of the building, the timings, the precision required, and how works a BIM software (Revit) and its libraries; we conclude that, in some particular projects, as far as technology and architecture field are nowadays, to make a useful documentation for rehabilitation modeling in BIM the building in a specific LoD directly from a point cloud (scan to BIM), it is an upgrade in the process beyond the fact of having a BIM model, that is to say, you can get the same documents, but with better quality results, in a more efficient way and less time spend. We ended up with a list of characteristics a building must have for this scan to BIM process is an efficient step and how this should be performed. This paper explores the efficiency of the Scan to BIM process for specific rehabilitation projects, testing it in two different case studies: a large scale building with repetitive elements (old military hospital in Valencia) and a small one with unique elements (classified single family house in Barcelona).