Reader for Arc/Info Triangulated Region Mesh
| Name | Type | Description | UI Control |
| filename | string | Name of TIN file to read. | File Dialog |
| ZScale | float | Elevation scaling applied to mesh. | Dial |
| ZeroElevations | boolean | Sets minimum elevation to zero. | Toggle |
| Name | Type | Description | |
| out_mesh | Triangle Mesh | Geometry data read from file. | |
| out_obj | DataObject | Directly Renderable Output Object. | |
The read_tin user macro reads Arc/Info TIN files. The TIN file format is an ASCII format thats stores a triangulated irregular network (TIN) structure generated by Arc/Info. More information on Arc/Info can be found on the ESRI web-site. This format is generally used for a surface representation derived from irregularly spaced sample points and breakline features. The TIN data set includes topological relationships between points and their proximal triangles. Each sample point has an x,y coordinate and a surface, or z-value. These points are connected by edges to form a set of nonoverlapping triangles used to represent the surface. The read_tin macro reads this data and outputs it as an unstructured mesh with a triangle cell-set. The macro uses the edge data to convert the edge-specified triangle data into node-specified triangle data. The edge data is not currently output as a separate cell-set.
TIN files are also called "irregular triangular mesh" or "irregular triangular surface model" in some contexts. "TIN" is the name of the ESRI Arc/Info application module that models, creates, displays, and exports TIN files. Within the TIN application the UNGENERATETIN command with the NET option should generate files compatible with this reader module.
filename
String parameter that contains the name of the TIN file that should be read. The filename can either by relative or absolute and it can contain AVS/Express environment variables (i.e. $XP_ROOT, $XP_PATH<1>).
ZScale
Floating point parameter that specifies by now much the elevation(Z) data should be scaled by. This parameter can be modified by the use of the 'Elevation Scale' dial.
ZeroElevations
Boolean parameter which specifies whether the geometry should be transformed in the z-axis so that the minimum elevation is zero. This can allow the TIN geometry to be more easily combined with other objects. This parameter is controlled by the use of the 'Zero Elevations' toggle.
out_mesh
Mesh data output that contains the geometry data read from the TIN file. The output consists of the nodal coordinates and a single triangle cell-set that describes the connectivity of the data. No node data or cell data is output.
out_obj
The directly renderable output of the read_tin macro. This output contains the geometry data read from the TIN file in a form that can be rendered by the standard data viewers.
The ReadTinFunc functional macro uses the ReadTinCore low-level module. The read_tin user macro uses this functional macro and the ReadTinUI user interface macro. All of these macros use the ReadTinParams parameter block to communicate parameters between themselves.
One example application is provided with the ReadTin project. The ReadTinEg example application reads a TIN file and displays the read geometry to the user.
iac_proj/rd_tin/tinmods.v contains the V definitions of the ReadTinCore module and the ReadTinParams parameter block.
iac_proj/rd_tin/tinmacs.v contains the V definitions of the ReadTinUI UI macro, the ReadTinFunc functional macro and the read_tin user macro.
iac_proj/rd_tin/tinapps.v contains the V definitions of the ReadTinEg example application.
Scott Goodyear
Mary McDerby, Manchester Visualization Centre Anja Bindrich, Manchester Visualization Centre Paul Lever, International AVS Centre Andrew Dodd, International AVS Centre
International AVS Centre Manchester Visualization Centre Manchester Computing University of Manchester Oxford Road Manchester United Kingdom M13 9PL