| Contents |
1. Introduction
2. File Formats 3. General File Structure |
4. Geometry File Structure
5. Scalar File Structure 6. Example Files |
Plane and surface probe data within LC can be saved into files in Movie.BYU file format. As the name implies, Movie.BYU originated from Brigham Young University as an animation storage and playback file format. It is also used within the visualization tool EnSight.
Movie.BYU describes a model in terms of its surfaces. The surfaces are composed of two dimensional elements of arbitrary shape.
Movie.BYU is actually a group of file formats which are used together.
The geometry file describes the physical layout of the object. For an LC plane probe, the layout is always a plane, oriented, scaled, and aligned identically as the probe within the LC model. The main difference is that the Movie.BYU plane has been meshed into elements corresponding to the FD-TD cells.
The file suffix used for the geometry file is usually .byu or .geo.
This file contains the data values, one for each node within the model.
Generally, there are a series of scalar files, one for each time step at which the data values are saved. The scalar file series are assigned sequence numbers, starting with 0. If the Time Factor for the probe within LC is set, then that number of time steps were computed between each file. If the Time Factor is not set, then one file is saved for each time step.
The file suffix used for the scalar file is usually .out or .scl.
This format is very much like the scalar file format, except there are three results per node (one each for the X, Y and Z vector components). This file format is not used within LC.
The file suffix used for the vector file is usually .out or .vec.
All of the Movie.BYU file formats are ASCII text file formats, with fixed field sizes and positions.
When a series of values are given to define a list, and the list exceeds the size allowed on a single line, then multiple lines are used, with each line packed with as many values as allowed. If the list does not contain the right number of values to exactly fill the last line, the last line is truncated, not padded.
The geometry file begins with a short header, followed by a list of parts, a list of nodes, and a list of edges.
The list of parts describes the individual components with a model. For a LC plane probe, there is just one part, a plane.
The list of nodes gives the (X,Y,Z) coordinates for each point where a data value will be given in the result files. The nodes are given in the same order in both the geometry file and the result files.
The list of edges describes the connectivity between the nodes within a part. This information can be used both for visually displaying the model, and for interpolating data values between nodes. The edge list defines the elements which make up the surfaces of the part. In LC, the elements are all have four edges connecting four nodes (these type of elements are often called quads).
The header contains four integer values on one line.
| Field | Format |
|---|---|
| Number of parts | I8 |
| Number of nodes | I8 |
| Number of elements | I8 |
| Number of edges | I8 |
Each part in the list is defined by two index values, the beginning and ending element number of the part. The elements for the part are always given in a contiguous block within the edge list.
The part element indicies are given with five parts (ten values) per line.
| Field | Format |
|---|---|
| Beginning element number | I8 |
| Ending element number | I8 |
The number of parts given in the list must correspond to the number of parts specified in the file header.
The nodes of the model are the (X,Y,Z) coordinates of each point which defines a vertex of an element. The nodes are given two per line, each node having three values. Thus, there are six values per line.
The nodes are implicitly numbered starting at 1 for the first node. These node numbers are used in the edge list to reference the nodes.
| Field | Format |
|---|---|
| X Coordinate | E12.5 |
| Y Coordinate | E12.5 |
| Z Coordinate | E12.5 |
The number of nodes given in the list must correspond to the number of nodes specified in the file header.
The nodes are connected together via the edges, which combine to form elements, which define the parts. The edge list actually consists of a list of elements, with each element being defined by edges between the nodes. Each value in the edge list is a node number.
A negative node number is given to signify the end of the current element. The magnitude of the node number identifies the corresponding node in this case.
The edges are implicitly numbered starting at 1 for the first edge. These edge numbers are used in the parts list to reference the edges. Individual elements are not referenced within the file, so no implicit numbering applies to them.
| Field | Format |
|---|---|
| Node number | I8 |
The number of edges given in the list must correspond to the number of edges specified in the file header. Also, the number of elements given in the list must correspond to the number of elements specified in the file header. This means that the number of negative node numbers in the edge list must equal the number of elements given inthe file header.
In the result files, the values are grouped six per line, in E12.5 format.
| Field | Format |
|---|---|
| Node value | E12.5 |
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The following information is subject to change. It can be used to read scalar files directly without deciphering the geometry file, but it makes assumptions about the order in which the scalar file is written. |
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In LC, the plane probe values are given in column major order. In this order, the X coordinate varies the fastest, Y varies next, and Z varies the slowest. In any plane, one of the three variations does not exist. For example, in a Z-plane probe, only X and Y vary (Z is constant). Thus, X varies the fastest. For a surface probe, the six faces are given in the following order:
Each face is a plane, and is given like an individual plane probe. |
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