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CCTAG scaling

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Simon edited this page Nov 20, 2020 · 36 revisions

CCTAGs can now be used to scale a model. (MR v.2020)

Note on CCTAG Markers: https://github.com/alicevision/CCTag/issues/141

  • Place two markers in your scene and capture the dataset (you should know the two marker IDs, as they can not be shown in the GUI at the moment) Measure the distance between the to Marker centre points. (Best use a distance of 10, 20,..., 100, ... mm)

  • Enable the DescriberType "CCTAG (3)" in FeatureExtraction (Do not disable SIFT here, it is still required)

  • Add the SfMTranform node:

sfmt1

OR

sfmt2

  • In SfMTranform only select cctag3

  • As Transformation Method select from_markers and add two markers. Insert the two marker IDs.

  • Let´s assume the distance between Marker0 and Marker1 is 100mm. To scale the Model to this known size, set the Marker1 x-coord to 1 (1 -> 100mm) and the Additional Scale to 1. (100*1). (The Coord. scale is 100mm per unit. In addition with the Additional Scale (multiplicand) other distances can be set). The origin of the coordinate system is set in the centre of the first Marker.

cctag

  • To apply the correct model orientation use a new SfMTranform node with Transformation Method manual transformation or Transformation Method "From_Single_Camera".

  • CCTAGs can also be used to align two models using the SFMAlignment node

https://groups.google.com/forum/#!topic/alicevision/t4kcSceAFD4 Similar to https://github.com/alicevision/meshroom/issues/1135

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