Virtual reality mapping system for Chernobyl accident site assessment

ABSTRACT Initiated by the Department of Energy's International Nuclear Safety Program, an effort is underway to deliver and deploy atelerobotic diagnostic system for structural evaluation and monitoring within the Chornobyl Unit-4 shelter. A mobile robot,named Pioneer, will enter the damaged Chornobyl structure and deploy devices to measure radiation, temperature andhumidity; acquire core samples of concrete structures for subsequent engineering analysis; and make photo-realistic three-dimensional (3D) maps of the building interior. This paper details the latter element, dubbed 'C-Map', the Chornobyl Mapping System. C-Map consists of an automated 3D modeling system using stereo computer vision along with an interactive, virtual reality (VR) software program to acquire and analyze the photo-realistic 3D maps of the damaged building interior. Keywords: Chornobyl, telerobotics, stereo vision, 3d surface reconstruction, virtual reality 1. INTRODUCTION The Chornobyl Mapping System (C-Map) is an automated 3D mapping system for requesting, creating, managing andinteractively displaying photo-realistic 3D models of the damaged nuclear power plant at the Chornobyl Unit-4 shelter in theUkraine. C-Map uses computer vision technologies with a virtual reality (VR) user interface for acquisition, modeling andanalysis of stereo image data sets. C-Map has been developed through collaboration between the NASA Ames ResearchCenter, Jet Propulsion Laboratory, Carnegie Mellon University and the University of Iowa. This robotic mapping tool allowsthe user to remotely reconstruct 3D models of the Chornobyl environment, fly-through the virtualized reality using stereoeye-wear, and make measurements of the surface topology. These data will be valuable for performing structural analysesand measurements, and estimating radioactive doses for stabilization planning as well. The visualization technology used forthis project is a derivative of the software called 'MarsMap', developed by the Intelligent Mechanisms Group at NASA Ames,for the very successful Pathfinder mission [1].The target operating environment for C-Map presented several challenges for development and required advances beyond thecapabilities of MarsMap. In order for C-Map to be operated by non system 'experts', the data processing and managementhad to be fully automated and the human interface simple to use and highly robust. Beyond the levels of radiation that limitshuman access, the dimly lit scene can cause failure in stereo correlation algorithms in matching features across image pairswithout adequate control and supervision over lighting. Also, the integration of a large number of data sets captured atdifferent robot locations and at different times into a unified map requires sophisticated mesh merging algorithms that relyupon accurate localization of the robot. Moreover, an intensive integration effort was required during a relatively short timeframe in order to adapt and combine separate pieces of technology (beyond just the MarsMap software capabilities) fromdifferent research institutions into a end-to-end product for automated 3d mapping and display.