Convert ParaView animations to Alembic
In order to polish a scientific visualization created in ParaView or incorporate the data into a work of art, one needs to export the data in a format that can be read by 3D graphics software like Maya. For polygonal data, the format should capture their geometry, normals, face & vertex attributes, and time dependence. ParaView's "Save Geometry" feature captures this information, but the resulting ".pvd", ".vtm", and ".vtp" are not understood by most other applications. The Alembic format is, however, and can represent this same information, along with things like object visibility and camera trajectories. The goal of this project is to provide a means of converting ParaView animation geometry to the Alembic format.
This project also serves as an example for using the VTK and Alembic libraries, whose API documentation is often lacking.
- Alembic and dependencies (https://github.com/alembic/alembic)
- VTK (http://www.vtk.org/)
- ParaView's "Save Geometry" feature handles object visibility in a
strange way. Any object not visible at the start of the animation will
be omitted from the export. And objects that lose visibility will
continue to reference the data from their last visible frame.
pvd2abctherefore assumes that any object referencing the same data as in the previous frame should be marked as invisible. The geometry for that frame is still saved, but will be constant throughout the period of invisibility (since ParaView doesn't export the actual data for those times).
pvd2abcalso provides a mechanism to mark objects that should be invisible on the first frame (but it relies on the ParaView source ID, which changes with each export).
- "vtkMultiBlockDataSet" (".vtm") files are assumed to contain a single DataSet pointing to a "PolyData" (".vtp") file. All of the geometry in the PolyData must be in the form of "Polys" (not "Strips"), and normals and scalar attributes must currently be "PointData", not "CellData".
- A user-specified scalar dataset may be used for grayscale coloring. It will be marked as "mayaColorSet".
- This code was written under a deadline, and the proper calls on the Alembic side were deduced from lots of trial and error. As a result, the code quality isn't as good as I'd like it to be. These origins are also why the output is focused on Maya instead of Blender.