Poisson Surface

Source file: poisson-surface.htm

The Poisson Surface tool uses the Poisson technique for creating closed solids of underground voids.

The Poisson Surface tool has the following advantages:

  • Is resilient to noisy data and misregistered artefacts.
  • Performs quick calculating and rendering processes.
  • Predicts where missing scan points should be and fill in those voids.
  • Detects any extra unwanted points and ignores them for the surface reconstruction.

Follow this procedure to create a Poisson surface:

  1. On the Labs ribbon tab, go to the Create group and select Poisson Surface.

  2. Under Output triangulation choose how to surface your selection. Select from:

    • Single surface
    • Single surface per object

  3. Under Point Normals, in the Nearest neighbour count field, enter the number of nearest neighbouring points to use for the surfacing calculations.

    • A larger count will make the surface smooth out more but you'll potentially lose sharpness around complex features.
    • A lower count will make the surface appearance coarser.

      • Tip:  In most situations, a Nearest neighbour count in the range of 3—20 is sufficient.

  4. Under Surface you can configure the parameters that affect the resulting surface creation.

    • Depth will determine the triangulation size used.
      • Lower values are sufficient for smooth surfaces with minimal noise.
      • Higher values manage noise better, for a more consistent surface.

      • Tip:  If the triangles are too big, try increasing Depth by 1. If the triangles are too small, decrease Depth by 1. Repeat until the result is satisfactory.

      Tip:  A Depth value between 8 and 16 will typically produce the optimal balance between surface clarity and detail.

    • Scale defines the maximum feature size the tool will process.

      • Increasing Scale will cover larger gaps and will completely close the ends of a tunnel, creating a closed solid. If Scale is too high it will increase the base triangle size of the surface it's creating, resulting in larger bulges at the ends of tunnels. This can cause it to lose some resolution on the walls.
      • Decreasing Scale might only triangulate the walls. If Scale is too small, the algorithm might not even triangulate all the walls.

        • Tip:  If you double Scale, increase Depth by 1 to keep the triangles the same size and retain fine detail.

      • Select Use linear fit if the surface reconstruction is to use linear interpolation to estimate the positions of the iso-vertices.

  5. Click OK or Apply.

    In the above example, the scan (left) had all the black areas (the voids) completely filled in (right) by using the Poisson surface tool. The details are preserved and edges are smoothed out.