Incorrect visualization of local axes for imported and/or curved 3D surfaces

ApplicationPLAXIS 3D
Issue status✔ Solved
First Affected VersionPLAXIS 3D 2011.00
Found in VersionPLAXIS 3D 2011.00
Fixed and Released in VersionPLAXIS 3D2012.02
Issue #17930
Date created11 October 2012
Date modified24 October 2016

Problem description

When inspecting the local axes for surfaces (e.g. plate, geogrids) it sometimes appears that the local axis are not pointing in a correct orthogonal system of axis, and axis 1 or axis 2 appear to be pointing out-of-plane. This is due to an issue in the visualization in the Input program.
Each surface in 3D Input is currently built up from (internally defined) triangles. Non-flat surfaces will contain multiple triangles that have different local axis directions, e.g. in the case of curved surfaces or imported surfaces. In those cases, the visualization will start with a smoothing to limit the amount of shown local axes on the surfaces to prevent too much clutter on screen, and keep a clear view.

However, when two connected parts of a single surface have opposing local axes, e.g. when axis-1 points in the (x,y,z)=(1,0,0) direction and the next connected internal triangle contains a local axis in which the axis-1 points in the (x,y,z)=(-1,0,0), the visualization of the local axes can go wrong and the axes seem to point in a random direction:

Common geometries where this may occur are:

This is just a visualization error of the PLAXIS 3D Input program.

Note: this problem does not appear when using the extrude functionality in PLAXIS 3D: in that case PLAXIS 3D has information about the shape and its direction: the defined extrusion direction or the extrusion path when extruding over a polycurve.


The only way to check in which direction these local axes are actually pointing, is in the generated mesh using the Output program: after mesh generation, inspect the generated mesh, and then select all plate elements (or geogrids) to be shown in a separate plot. Make sure to activate the local axes from the View menu:

This visualization issue in the 3D Input program is fixed since PLAXIS 3D2012.02