#!F-adobe-helvetica-medium-r-normal--18* #!N #!CSeaGreen #!N #!Rall192 Identifying Connections #!N #!EC #!N #!N In Data Explorer, we identify connections in the following way. List the sample point location vertices in any order: that list is called the "positions" as we discussed above. Consider each point in the positions list to have an ordinal number, starting at 0 for the first point in the list (these ordinal numbers are not explicitly listed in a Data Explorer file). A connection is denoted by a "list of lists" of numbers in which each entry represents the ordinal values of the points that are to be connected, listed in the order they are to be connected. So for example, if the first point in the positions list is "0.0 0.0" and the second point is "1.0 0.0," we denote a #!F-adobe-times-medium-i-normal--18* line #!EF connection between these two points by "0 1," indicating that a line joins point 0 (first point in the positions list) to point 1 (the second point in the list). #!N #!N As mentioned above, a #!F-adobe-times-medium-i-normal--18* triangle #!EF connection must reference three positions and a #!F-adobe-times-medium-i-normal--18* quad #!EF references four positions. For complete examples of position and connection lists, see #!Ldatmod,dxall197 h Understanding the Data Model #!EL . #!N #!N As a direct extension of this concept, when we define volumetric elements like #!F-adobe-times-medium-i-normal--18* cubes #!EF and #!F-adobe-times-medium-i-normal--18* tetrahedra #!EF , we can perform 3-dimensional interpolation and derive a reasonable data value for any point in a sample volume. The good news about all of this interpolation is that Data Explorer already knows how to do the necessary calculations. As a researcher, your job is to define your data space to Data Explorer--its positions, connections, and data-dependency--but you do not have to worry about the details of how the interpolation is actually performed. #!N #!N The connections list is optional if it makes no sense to connect your sample points; for example, if you are studying gas molecules, there may be no meaningful interconnecting lines between separate molecules. Nevertheless, you may wish to define "line" connections linking the atoms within each molecule, in order to visualize interatomic bonds or protein backbones; or you may define cubic volumetric elements in the space around the nucleus if you wish to visualize electronic potential fields, for instance. #!N #!N In any case, you must define a set of connections before you can perform interpolation operations between sampled data values. This is true both for position-dependent data and for connection-dependent data. Once again, positions are discrete points in space, and connections are logical paths between those points representing reasonable interpolation paths between the sampled data values. If you do not have connection information available, you can use the Connect or Regrid modules to create connections for scattered point data. #!N #!N If you work with regular grids, the "connections" can be defined in a simple way by Data Explorer regardless of the import format you are using. See #!Ldatmod,dxall197 h Understanding the Data Model #!EL in this Guide and #!Lqimd,dxall109 h Importing Data #!EL in IBM Visualization Data Explorer QuickStart Guide. #!N #!N If your work requires irregular grids, you will need to carefully read the section of this manual that describes the format of Data Explorer element types. You may need to write a filter program to convert the connection list output from your finite element program to the format required by Data Explorer before you can import and visualize data sampled on arbitrary structures. #!N #!N #!N #!F-adobe-times-medium-i-normal--18* Next Topic #!EF #!N #!N #!Linvdat,dxall194 h Invalid Data #!EL #!N #!F-adobe-times-medium-i-normal--18* #!N
Generated by dwww version 1.15 on Sat Jun 22 13:01:29 CEST 2024.