Consolidated Visualization of Enormous 3D Scan Point Clouds with Scanopy Claus Scheiblauer 1 Michael Pregesbauer 2 1 Institute of Computer Graphics and Algorithms, Vienna University of Technology, Austria 2 Government of Lower Austria, Austria

Screenshot Claus Scheiblauer 1

Scanning Project Area Amphitheater 1, Bad Deutsch-Altenburg Claus Scheiblauer 2

Motivation Excavation accompanying data acquisition Documentation of the ancient amphitheatre Creation of a 3D model of the whole amphitheatre Claus Scheiblauer 3

Scanning Project Data aquisition between 2008 and 2010 Laserscanner system Riegl LMS 420i 120 scan positions 106M points Claus Scheiblauer 4

Data Aquisition Geocoding within a national global reference system Coarse registration with tie points Fine registration by using identical patches for a multi station adjustment Scan position accuracy 1 - 2cm Claus Scheiblauer 5

Point Cloud Rendering with weighted point size One color per splat Claus Scheiblauer 6

Point Cloud Rendering with weighted point size One color per pixel Claus Scheiblauer 7

Averaging Colors One color per splat Arbitrary color borders Color noise due to Overlapping splats Points from scan positions far away One color per pixel Pixel color is averaged from contributing splats Reduced color noise Claus Scheiblauer 8

Gaussian Splats Splat size is know Screen aligned splats Pixels are weighted according to distance from center Gaussian distribution At each pixel the colors from different splats are blended According to their weight Claus Scheiblauer 9 0.4

Gaussian Splats Blending Only splats up to a certain depth distance should be blended Some heuristic Uniform sampled point clouds without noise Distance = splat radius Non uniform sampled with noise Distance = some constant Claus Scheiblauer 10

Gaussian Splats Multipass Splatting is divided into 3 passes Depth pass First a depth image is created Attribute pass Only visible points contribute color values Colors are weighted and blended Normalization pass The colors are normalized at each pixel Claus Scheiblauer 11

Gaussian Splats Properties + Splat sizes that are “too big” give better result + Color noise is reduced + Features become more visible - Increased rendering time Claus Scheiblauer 12

Acknowledgements FFG FIT-IT Projekt “Terapoints” Government of Lower Austria Imagination Computer Services Claus Scheiblauer 13

Live Demo Amphitheatre 1 in Bad Deutsch-Altenburg 106M points 1.6 GB data on disk Claus Scheiblauer 14