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Surface Reconstruction from Multi-View Stereo of Large-Scale Outdoor Scenes

Author: Salman

Year: 2010

Notes:

  • Dense 3D point cloud from multiview stereo, uses 2D delaunay triangulation
  • according to A comparison and evaluation of multi-view stereo reconstruction algorithms, 4 class of methods:
    • working on a 3D volume
    • variationnal methods
    • fusing multiple depth maps
    • extract 3D points and fit a surface
  • A triangular depth map is made for each images, then triangles lifted in 3D. The triangle soup is refined by combining visibility and photo consistency constraints (?)
  • The Voronoi cell $V(p_i)$ , associated to a point $p_i$ , is the region of points that are closer to $p_i$ than to all other sites in $P$
  • Takes as input a set of calibrated images and a set of tracks
  • Several steps:
    • Merging close tracks
    • Filters outliers by distance to nearest neighbours and low parallax
    • Smooth the surface by polynomial fitting of the neighbours of each point and reprojection
    • Detects contour by gaussian filter + canny, 2D triangulation over all tracks and 3D lifting
    • filter triangle soup
  • Filter triangle soup:
    • visibility constraint: remove any triangle that is crossed by the ray of a 3D point
    • if the angle between the normal and the ray of its vertex is over 80°
    • big triangles that have normal shape have photoconsistency check i.e the triangle on every view should have a small NCC
  • Reconstruction with Provably good sampling and meshing of surfaces but it needs a prior