Volume IV-2
ISPRS Ann. Photogramm. Remote Sens. Spatial Inf. Sci., IV-2, 193-200, 2018
https://doi.org/10.5194/isprs-annals-IV-2-193-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
ISPRS Ann. Photogramm. Remote Sens. Spatial Inf. Sci., IV-2, 193-200, 2018
https://doi.org/10.5194/isprs-annals-IV-2-193-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

  28 May 2018

28 May 2018

SUB-PIXEL ACCURACY CRACK WIDTH DETERMINATION ON CONCRETE BEAMS IN LOAD TESTS BY TRIANGLE MESH GEOMETRY ANALYSIS

F. Liebold and H.-G. Maas F. Liebold and H.-G. Maas
  • Institute of Photogrammetry and Remote Sensing, Technische Universit¨at Dresden, Germany

Keywords: Material Testing, Deformation Measurement, Triangle Mesh, Crack Width, Principal Strain

Abstract. This paper deals with the determination of crack widths of concrete beams during load tests from monocular image sequences. The procedure starts in a reference image of the probe with suitable surface texture under zero load, where a large number of points is defined by an interest operator. Then a triangulated irregular network is established to connect the points. Image sequences are recorded during load tests with the load increasing continuously or stepwise, or at intermittently changing load. The vertices of the triangles are tracked through the consecutive images of the sequence with sub-pixel accuracy by least squares matching. All triangles are then analyzed for changes by principal strain calculation. For each triangle showing significant strain, a crack width is computed by a thorough geometric analysis of the relative movement of the vertices.