Abstract
Historic building information modeling (HBIM) provides an index frame for digital documentation of the cultural heritage, as a continuous process of reverse engineering. The index frame should be a regular model, with a clear comprehension of each component; consequently, associated knowledge could be live-updated with the investigation progress. Therefore, the method of data registration stresses its importance. The axis is fundamental for Chinese traditional architecture as the basis for positioning all components in wooden structures. However, displacement often happens. To correct the displacement while modeling, the hypothetical axis should be determined first. This paper thus proposes a method of generating the regular axis from irregular column grids and aims to develop an automatic solution that is repeatable and transplantable. The finite element modeling (FEM) abstracts the actual problem to enable numerical calculation. Starting from a candidate solution, the genetic algorithm calculates a solution closest to the expectation from the possible solutions in several minutes. The standard deviation is used to measure the amount of displacement based on the hypothetical axis, which is expected to be minimum. This method is compatible with most kinds of input data, e.g., point cloud, excel data, 2D drawing, mesh model, etc., and applied to a World Heritage Site in Qufu (Shandong, China). The results show the displacement of columns with visual expression and numerical analysis and prove that the proposed method is repeatable and traceable and can easily be applied to different projects by changing input parameters.
Highlights
During the digital documentation of cultural heritage, displacements are usually found in wooden structures [1–4], resulting in difficulty of positioning while modeling
The solution process takes 3 h 16 min and stops automatically after reaching the minimum value. This result shows that the manually rotated point cloud is very close to the orthogonal direction as the initial angle is 0.00002 degrees
This method is proposed for the correction of an irregular grid system; the result could accurately restore the original axes under certain conditions
Summary
During the digital documentation of cultural heritage, displacements are usually found in wooden structures [1–4], resulting in difficulty of positioning while modeling. Because eave columns are inclined and raised in an arithmetic sequence, from center to corner, the plane projection of centroids connection line of eave column heads is rectangular, while the eave column feet are not This manufacturing method is documented in “Ying Zao Fa Shi” [5–9] (which states building regulations of Song Dynasty, A.D. 1103), and it can be seen in many heritage sites in East Asia nowadays. The method of algorithm modeling (or generative modeling) with visual programming tools is developing increasingly [22–31] This technique provides traceable solutions which document the whole modeling procedure, including input parameters, process algorithms, and resulting models. Based on this foundation, the research that considers grids as a whole of the interrelated system cloud be further developed. The Galapagos as an evolutionary solver in Grasshopper has been widely used for parametric design and result optimization [38–46]
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