Exporting Volumetric Data

The Volumetric object, which includes a spatial calculation evaluated over time, can export its computed data to an external file using the HDF5 format.

To export Volumetric data, select Export... from the Volumetric menu.

Exported data always includes times and values computed at grid points.

For certain calculations, values generated by STK for each grid point are derived solely from availability and satisfaction intervals. In these cases, STK can generate these values at any time as needed for animation or reporting without having them pre-computed over set times specified beforehand.

However, when exporting volumetric data, the resulting file must explicitly contain values at all times that may be of interest. Therefore, while it may be unnecessary for evaluation within STK, the times must be specified before attempting to export the resulting values. This is controlled by the Evaluation of Spatial Calculation setting found on the Volumetric Properties > Basic > Interval page, which is set to At instant in time by default. If volumetric data is exported with this default setting, it will only be exported for the time instant currently set in the animation. To export the data for the entire interval of interest, discrete time steps must be used. To achieve this, select either At times from Time Array or At times at step size before exporting the volumetric data.

The following options allow you to control how much information to include in the file and how specific it should be.

Option	Description
Include link to Volume Grid	Links to the Volume Grid selected in the Volumetric object. Choose this option if you plan on bringing the volumetric data file back into the same scenario with the original grid.
Embed Volume Grid definition	Embeds a complete definition of the Volume Grid in the external file. Select this option if you plan on bringing the volumetric data file back into a different STK scenario or an external program. This option includes two sub-options: Include Point Coordinates option Select whether to include actual grid point locations in Cartesian or native coordinates (e.g., latitude, longitude, altitude for Cartographic grids, etc.). It is recommended that you do NOT select this option if the exported file is intended for use in STK because the grid points will be regenerated based on the embedded grid definition. Select this option if an external program may find it useful to have actual grid point coordinates included in the exported file, although, of course, at the expense of increased file size. Include Grid Reference option Select whether to include a link to the reference system used to anchor the grid points (Central body reference for Cartographic grids). The option refers to the coordinate system (or the central body for grids that use Cartographic information) in which the grid points are defined. If disabled, you will be prompted on load to specify a reference. This can be useful if the exported grid needs to be moved to a different reference on load.
Export Data to:	Name and location of exported volumetric data file.

Option

Description

Include link to Volume Grid

Links to the Volume Grid selected in the Volumetric object.

Choose this option if you plan on bringing the volumetric data file back into the same scenario with the original grid.

Embed Volume Grid definition

Embeds a complete definition of the Volume Grid in the external file.

Select this option if you plan on bringing the volumetric data file back into a different STK scenario or an external program.

This option includes two sub-options:

Include Point Coordinates option

Select whether to include actual grid point locations in Cartesian or native coordinates (e.g., latitude, longitude, altitude for Cartographic grids, etc.).

It is recommended that you do NOT select this option if the exported file is intended for use in STK because the grid points will be regenerated based on the embedded grid definition.

Select this option if an external program may find it useful to have actual grid point coordinates included in the exported file, although, of course, at the expense of increased file size.

Include Grid Reference option

Select whether to include a link to the reference system used to anchor the grid points (Central body reference for Cartographic grids).

The option refers to the coordinate system (or the central body for grids that use Cartographic information) in which the grid points are defined. If disabled, you will be prompted on load to specify a reference. This can be useful if the exported grid needs to be moved to a different reference on load.

Export Data to:

Name and location of exported volumetric data file.

Loading Volumetric Data Back into STK

These external files containing computed volumetric data can be loaded back into STK as well as into other tools, such as MATLAB. When loading into STK, the Volume grid information stored in these files is handled as follows:

If the file contains a link to the Volume grid, then it is expected that this grid already exists in the STK scenario.
If the file contains an embedded definition of the Volume grid, then this definition is used. However,

if a link to the grid reference is included, then this reference system must already exist in the scenario.
if a link to the grid reference is not included, then you will be prompted to select one of the existing reference systems to anchor the grid.