An economical approach to geo-referencing 3D model for integration of BIM and GIS

Abstract

The integration of building information modelling (BIM) and geographic information system (GIS) has been studied for a long period of time by researchers from both domains. The foundation of the integration is the interoperability of the data, which means the BIM data has to have a right reference system, allowing it to be read correctly by GIS software applications. 3D models from the BIM world may not be correctly georeferenced, which impairs the data interoperability. Instead of rebuilding models from scratch, which is time- and labour-consuming, this paper proposes a more efficient, economical, two-step alternative mainly based on Affine transformation. In the first step, the modification is made against the x- and y-coordinates. A number of control points would be selected to form displacement links. Based on these, the transformation parameters would be calculated, and the 2D footprint of the model would be rectified by Affine transformation. Then, the z-value (height information) of each vertex in the model would be adjusted using the scaling factor f. This method could obtain a 3D model without a geographical coordinate system correctly geo-referenced, and thus, it could be further read by GIS applications, consuming the vast spatial analysis tools supported by the GIS world, achieving more than just visualization. The key to the success of this study is creating an accurate right footprint of the model and selecting appropriate control points to guarantee the accuracy of transformation. By far, this approach has only been tested with a bridge model, its performance on other building models needs to be further studied.