Capturing Village-level Heritages with a Hand-held Camera-Laser Fusion Sensor

Abstract

Preserving a heritage as a digital archive is as important as preserving its physical structure. The digital preservation is essential for massive heritages which are often defenceless against various types of destruction and require frequent restorations. However, capturing heritages gets exceedingly harder as their scale grows. In this paper, we present a novel approach to reconstruct a massive-scale structure using a hand-held fusion sensor system. The approach includes new methods on calibration, motion estimation, and accumulated error reduction. The proposed sensor system consists of four cameras and two 2D laser scanners to obtain a wide field-of-view. A new calibration method successfully achieves a much lower reprojection error compared to the previous method. A motion estimation method provides accurate and robust relative poses by fully utilizing plenty observations. At the last stage, the accumulated error reduction removes the drift occurred over tens of thousands frames by adopting weak GPS prior and loop closing. Therefore the system is able to capture and geo-register large heritage architectures of square kilometers size. Furthermore, because no assumption or restriction is made, the user can freely move the system and can control the level of detail of the digital heritage without any effort. To demonstrate the performance, we have captured several important Korean heritages including Gyeongbok-Gung, the royal palace of Korea. The experimental result shows that the estimated route fits Google's satellite image and DGPS data while the detailed appearances of representative constructions are captured and preserved well.