From cdc91a18577bcc2a7e6b8d49086019340508112e Mon Sep 17 00:00:00 2001 From: "Praetorius, Simon" <simon.praetorius@tu-dresden.de> Date: Thu, 21 Feb 2019 11:26:03 +0100 Subject: [PATCH] Update README.md --- README.md | 72 +++++++++++++++++++++++++++++++++++++++---------------- 1 file changed, 51 insertions(+), 21 deletions(-) diff --git a/README.md b/README.md index b7e6c04..774b956 100644 --- a/README.md +++ b/README.md @@ -63,42 +63,72 @@ proposed one. A comparions: | Timeseries | - | **x** | ## Writers and Readers -Dune-Vtk provides nearly all file formats specified in VTK + 2 time series formats: PVD and VTK-Timeseries. +Dune-Vtk provides nearly all file formats specified in VTK + 2 time series formats: +PVD and VTK-Timeseries. ### VtkUnstructuredGridWriter -Implements a VTK file format for unstructured grids with arbitrary element types in 1d, 2d, and 3d. Coordinates are specified explicitly and a connectivity table + element types are specified for all grid elements (of codim 0). Can be used with all Dune grid types. +Implements a VTK file format for unstructured grids with arbitrary element types +in 1d, 2d, and 3d. Coordinates are specified explicitly and a connectivity table + +element types are specified for all grid elements (of codim 0). Can be used with +all Dune grid types. ### VtkStructuredGridWriter -Implements a writer for grid composed of cube elements (lines, pixels, voxels) with local numbering similar to Dunes `cube(d)` numbering. The coordinates of the vertices can be arbitrary but the connectivity is implicitly given and equals that of `Dune::YaspGrid` or `Dune::SPGrid`. Might be chosen as writer for a transformed structured grid, using, e.g., a `GeometryGrid` meta-grid. See `src/geometrygrid.cc` for an example. +Implements a writer for grid composed of cube elements (lines, pixels, voxels) with +local numbering similar to Dunes `cube(d)` numbering. The coordinates of the vertices +can be arbitrary but the connectivity is implicitly given and equals that of +`Dune::YaspGrid` or `Dune::SPGrid`. Might be chosen as writer for a transformed +structured grid, using, e.g., a `GeometryGrid` meta-grid. See `src/geometrygrid.cc` +for an example. ### VtkRectilinearGridWriter -Rectilinear grids are tensor-product grids with given coordinates along the x, y, and z axes. Therefore, the grid must allow to extract these 1d coordinates and a specialization for a `StructuredDataCollector` must be provided, that implements the `ordinates()` function. By default, it assumes constant grid spacing starting from a lower left corner. For `YaspGrid` a specialization is implemented if the coordinates type is `TensorProductCoordinates`. See `src/structuredgridwriter.cc` for an example. +Rectilinear grids are tensor-product grids with given coordinates along the x, y, +and z axes. Therefore, the grid must allow to extract these 1d coordinates and a +specialization for a `StructuredDataCollector` must be provided, that implements +the `ordinates()` function. By default, it assumes constant grid spacing starting +from a lower left corner. For `YaspGrid` a specialization is implemented if the +coordinates type is `TensorProductCoordinates`. See `src/structuredgridwriter.cc` +for an example. ### VtkImageDataWriter -The *most structured* grid is composed of axis-parallel cube elements with constant size along each axis. The is implemented in the VtkImageDataWriter. A specialization of the `StructuredDataCollector` must implement `origin()` for the lower left corner, `wholeExtent()` for the range of cell numbers along each axis in the global grid, `extent()` for the range in the local grid, and `spacing()` for the constant grid spacing in each direction. +The *most structured* grid is composed of axis-parallel cube elements with constant +size along each axis. The is implemented in the VtkImageDataWriter. A specialization +of the `StructuredDataCollector` must implement `origin()` for the lower left corner, +`wholeExtent()` for the range of cell numbers along each axis in the global grid, +`extent()` for the range in the local grid, and `spacing()` for the constant grid +spacing in each direction. ### PvdWriter -A sequence writer, i.e. a collection of timestep files, in the ParaView Data (PVD) format. Supports all VtkWriters for the timestep output. In each timestep a collection (.pvd) file is created. - -**TODO:** - -- Just append the new timestep to the file instead of recreating it. +A sequence writer, i.e. a collection of timestep files, in the ParaView Data (PVD) +format. Supports all VtkWriters for the timestep output. In each timestep a collection +(.pvd) file is created. ### VtkTimseriesWriter -A timeseries is a collection of timesteps stored in one file, instead of separate files for each timestep value. Since in the `Vtk::APPENDED` mode, the data is written as binary blocks in the appended section of the file and references by an offset in the XML DataArray attributes, it allows to reuse written data. An example of usage is when the grid points and cells do not change over time, but just the point-/cell-data. Then, the grid is written only once and the data is just appended. - -Timeseries file are create a bit differently from other Vtk file. There, in the first write the grid points and cells are stored in a separate file, and in each timestep just the data is written also to temporary files. When you need the timeseries file, these stored temporaries are collected and combined to one VTK file. Thus, only the minimum amount of data is written in each timestep. The intermediate files are stored, by default, in a `/tmp` folder, with (hopefully) fast write access. - -**Limitations:** - -- Maximum 1000 timesteps can be written. This is a limitation of VTK. (Limitation removed in recent VTK versions) - -**TODO:** - -- Allow to specify the `/tmp` folder by the user. +A timeseries is a collection of timesteps stored in one file, instead of separate +files for each timestep value. Since in the `Vtk::APPENDED` mode, the data is written +as binary blocks in the appended section of the file and references by an offset +in the XML DataArray attributes, it allows to reuse written data. An example of +usage is when the grid points and cells do not change over time, but just the +point-/cell-data. Then, the grid is written only once and the data is just appended. + +Timeseries file are create a bit differently from other Vtk file. There, in the +first write the grid points and cells are stored in a separate file, and in each +timestep just the data is written also to temporary files. When you need the timeseries +file, these stored temporaries are collected and combined to one VTK file. Thus, +only the minimum amount of data is written in each timestep. The intermediate files +are stored, by default, in a `/tmp` folder, with (hopefully) fast write access. ### VtkReader Read in unstructured grid files (.vtu files) and create a new grid, using a GridFactory. +The reader allows to create the grid in multiple ways, by providing a `GridCreator` +template parameter. The `ContinuousGridCreator` reads the connectivity of the grid +as it is and assumes that the elements are already connected correctly. On the other +hand, a `DiscontinuousGridCreator` reconnects separated elements, by identifying +matching coordinates of the cell vertices. + +The VtkReader supports grid creation in parallel. If a partition file .pvtu is +provided, all partitions can be read by 1. one processor and distributed later on +(`SerialGridCreator`) or read directly in parallel (`ParallelGridCreator`). The later +is currently only available in dune-alugrid 2.6. **TODO:** -- GitLab