An Automated System for Projection of Interior Construction Layouts

Layout of the interior works during building construction is time consuming and error prone. Given the cost involved, both for initial layout and for later rework where errors occur, researchers have sought to automate the layout task. Some have adopted marker-less augmented reality methods using heads-up displays or cameras, and others have proposed robots capable of marking out the works. The former encumber the workers, the latter are expensive to set up and are sensitive to site conditions, and neither has yet achieved the required accuracy. In this paper, we propose a more efficient approach to project relevant information from a building information model (BIM) onto the construction surface, directly augmenting the construction site with the design information. This is done using a portable system consisting of a 2-D laser scanner, an angled adjustable projector, and a camera. The system localizes itself within the already built outer walls using the laser scanner and the BIM model using a method derived from robotic mapping; it calibrates the projection correction parameters (keystone correction) using image analysis; and it projects the information with the angled projector. Testing results showed that the localization was accurate within a few millimeters and less than 3 degrees, and the final projected image's error was approximately 1 cm. Initial calibration requires less than 1 min and does not require specialist skills. The system automates the layout task, preserves accuracy, and can provide rich model information on any interior surface. Note to Practitioners-Measuring and marking up of the interior works during building construction is time consuming and error prone. Layout must be repeated for each trade: partitions, false ceilings, mechanical, electrical, and plumbing systems, and flooring and furnishings all require accurate marking of locations on floors, walls, and ceiling surfaces. Current automation is limited to the use of robotic total stations, but these only locate specific predetermined points. We propose a simple solution for automated layout, in which images from a building information model are projected directly onto the work surface. The system projects any desired information-drawings and images-onto the work surface (floor, walls, or ceiling) in the correct location, scale, and orientation. The prototype apparatus consists of a laser range scanner, a projector, and a camera. Projection of the work instructions directly onto the work surface is accurate and immediate. It saves the time required for workers to interpret and then mark up the dimensional information and it avoids the human error involved. The prototype is limited to environments in which computer projection is practical and currently requires planar surfaces.