Assessment of the quality of as-is building information models generated from point clouds using deviation analysis

Abstract

Three dimensional (3D) imaging sensors, such as laser scanners, are being used to create building information models (BIMs) of the as-is conditions of buildings and other facilities. Quality assurance (QA) needs to be conducted to ensure that the models accurately depict the as-is conditions. We propose a new approach for QA that analyzes patterns in the raw 3D data and compares the 3D data with the as-is BIM geometry to identify potential errors in the model. This "deviation analysis" approach to QA enables users to analyze the regions with significant differences between the 3D data and the reconstructed model or between the 3D data of individual laser scans. This method can help identify the sources of errors and does not require additional physical access to the facility. To show the approach's potential effectiveness, we conducted case studies of several professionally conducted as-is BIM projects. We compared the deviation analysis method to an alternative method -the physical measurement approach -in terms of errors detected and coverage. We also conducted a survey and evaluation of commercial software with relevant capabilities and identified technology gaps that need to be addressed to fully exploit the deviation analysis approach.

Representation Requirements of As-Is Building Information Models Generated from Laser Scanned Point Cloud Data

“…To our best knowledge, existing software cannot compute these properties on a BIM. Although, certain software can perform deviation analysis on CAD objects, BIM to CAD conversion ultimately causes information loss [1].…”

“…First, deviation information can be used to represent the surface geometries where accurately modeling the surfaces is not possible or practical. Secondly, deviation maps can be used to assess the quality of the as-is BIMs [1].…”

“…Using laser scanners is becoming a common practice for collecting data for generating as-is BIMs by private owners and government agencies, due to its high accuracy, speed, and coverage [1,2]. However, current practices of as-is BIM generation from laser scanner data and representation approaches are based on existing as-designed modeling approaches.…”

Scan-to-Bim Output Validation: Towards a Standardized Geometric Quality Assessment of Building Information Models Based on Point Clouds

“…A starting point in literature was provided by (Anil et al, 2011, Anil et al, 2013. The focus in these successive papers is mainly on the detection and classification of modeling errors or errors that appeared during the data collection or post-processing phase.…”

“…The results of the deviation analysis can be represented in multiple ways: graphical with the use of 2D or 3D color maps (binary or gradient, signed or unsigned) (Anil et al, 2011) or numerical (e.g. % of points within a certain LOA range).…”