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Basic Information

Name of Program



3.x / February 2010


February 2010


input for standard visualization software
synoptic dataset
two dimensional(2D), three dimensional(3D)
volume model
universal direct access format
alternative / time dependent bathymetry
UCD format
Tecplot format

Short Description of Functionality

The program io_volume can be used to convert bathymetries and hydrological datasets used in hydro numeric models into formats readable by standard software. The input datasets must be synoptic and have to contain area data (neither profiles nor locations). They can be two dimensional (e.g. waterlevel) or three dimensional (e.g. salinity varying with water depth).

The data model of the converted datasets is called a volume model and contains 3D node coordinates and a 3D connectivity table.


  1. general input data (file of type io_volume.dat)
  2. bathymetry of a hydronumerical model (file of type untrim_grid.dat, gitter05.dat/bin or selafin (only bathymetry is evaluated))
  3. (optional) depth values of the horizontal layers (files of type vertical.dat); depth values contained in the meta data of the datasets overwrite this information
  4. (optional) synoptic datasets (area, 2D/3D) of a hydronumerical model (files in the universal direct access format see also dirz.bin or of type netcdf.cdf);


The supported ucd format is a format mainly used by AVS/Express. Compared with the classic UCD format it can contain time dependent data.

  1. (optional) bathymetry as a surface (2D) ( file of type ucd or tecplot; if a time dependent bathymetry is given, this file will have time dependent values)
  2. (optional) bathymetry as a spatial body (3D) ( file of type ucd or tecplot)
  3. (optional) hydrological data as a surface (2D physical measures) ( file of type ucd or tecplot )
  4. (optional) hydrological data as a spatial body (3D physical measures) ( file of type ucd or tecplot )
  5. (optional) lineprinter file containing useful information related to program execution (filetype io_volume.sdr);


Results in the universal direct access format are stored in a layer model which consists of a two dimensional horizontal grid and the depths of the horizontal layers. This kind of storage is well suitable for the hydronumerical models because it describes the physics of the models with constant results in one layer above a 2D node. But standard visualization software can not "understand" this data model.

layer model:Converting the results from a layer model as it is used in UNTRIM to a volume model suitable for visualization.

Standard software needs a 3D grid with node coordinates as well as a 3D connectivity table. This kind of data model is from now on called a volume model. At the moment supported cell types are triangle and quadriliteral for physical measures with 2D information and prism and hexahedron for 3D measures.

The free water surface represents the upper limit of the hydrological dataset. Because it rises and falls driven by the tides the shape and the size of the grid are time dependent. In visualization terms the grid is called transient.

Result values are in a layer model constant in one horizontal layer above a node. Io_volume projects the values onto the nodes (see fig. 1). If the coverage of one node of a cell is too small, the whole cell will be dry and will not be displayed. This leads to steps on top of the hydrological datasets which are accepted at the edges. Inside the surface this looks nasty and does not represent the physics of the model correctly. Therefore the z coordinate of the node below takes the value of the water surface and the physical measures get extrapolated. This is valid analogously for the nodes and cells in the lowest layer. Everybody who analyses the converted data should keep these possible extrapolations in mind.

Optionally a null value can be set. If Tecplot is used with the blanking value -999., dry 2D nodes will not be displayed.

New in version 3.1:

Io_volume takes now into account dynamic / alternative bathymetry depths as well as a system slope. The wet / dry decision in 2D datasets is then done by using the dynamic bathymetry. Nodes of a 3D body, which lay below the dynamic soil, are marked by values of the null value. The blanking feature enables Tecplot not to display these nodes. Fig. 2 displays a DredgeSim-SediMorph-UnTRIM example, where the null values are alternatively marked by the deepest blue, visualising the position of the layer between static and dynamic soil.

Slices of suspension in a channel with dredging and dumping activity

For software developers:

Io_volume is mainly based on the software package "volume".

Its complex datatype t_volume can be extended to further cell types( e.g. lines which would enable the conversion of profile data). The storage of cell data is partly included.

You can use the module m_volume_ucd as a template for the integration of other output formats.

Program(s) to run before this Program


Program(s) to run after this Program

AVS/Express (ungetestet), TECPLOT

Additional Information



Additional software


Original Version

P. Schade


P. Schade



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