3D Visualization

A very lightweight layer for visualizing ACTS geometry objects and event data model is provided within the Core component. ACTS does not provide a viewer per se, but instead it was chosen to plug a visitor that can then be used for visualizing the given objects. The visitor has to implement the IVisualization3D interface and can then straight forwardly used with the visualization helper structs. Two visualization helpers that implement industry standard 3D formats can be used from this component, but evidently any other visitor can be plugged in as long as it satisfies the IVisualization interface.

The two provided visualization visitors are:

• ObjVisualization3D writing the .obj format, and an associated .mtl file for the color and material definitions

• PlyVisualization3D writing the .ply format, which contains already the color/material information

Behind the scenes

All display actions rely on the Polyhedron representation of Surfaces, i.e. each surface can be at least approximated by a list of vertices and a definition of faces connecting these vertices. As a special feature, the Polyhedron can be displayed as a triangulated mesh of surfaces, i.e. each surface is divided into triangles that build up the object to display.

Convenience helper functions

The visualization package also contains static helper functions for displaying complicated objects; these helper functions are provided by the GeometryView3D and EventDataView3D structs, that receive:

• A visualization visitor

• The object to be written

• A geometry context where needed

• Some view configuration, which is simply handled by the ViewConfig struct.

The ViewConfig struct contains a number of parameters, such as the visibility flag, the RGB color definition of the object (or its contained objects), and some other view parameters that can be changed.

The Tests/UnitsTests/Core/Visualization package contains a certain number of tests that produce output files to be visualized with any standard 3D viewer.

Example of an angular error cone:

Example of a 2D cartesian error on a plane:

Example of track parameters on a plane:

Example of a cylindrical layer with sensitive volumes and a surface grid: