The Visum surface model consists of the following seven tables. In these tables, the surfaces of all network objects are displayed. The tables are explained with the aid of an example.
|
Note: In Visum, you can save polygons together with the network object type using them to a network file (Using Visum: Opening and saving a network file and adding comments). However, thereby all polygons are saved, independent of whether they were used for an object of the type specified or not. |
Example
In the following example, the seven tables are displayed and explained for a network that contains three main nodes with surfaces.
The network includes the three main nodes with the IDs 2, 3 and 4. These main nodes are allocated via the SurfaceID attribute to the surfaces with the IDs 866, 867 and 868 (Table 30).
* Table: Main nodes $MAINNODE:NO;SURFACEID 2;866 3;867 4;868 |
In the Surfaces table, all surfaces contained in the network are stored with their IDs. Since, in the example, only the three main nodes have a surface, there are exactly three entries for the main node surfaces in this instance (Table 31).
* Table: Surfaces $SURFACE:ID 866 867 868 |
Each surface is composed of one or multiple faces. The allocation of surfaces to faces is carried out in table Surface items. In the example, the surfaces 866 and 868 have exactly one face, whereas surface 869 has two faces. Thus, there are four faces in total with the IDs 1139, 1141, 1144 and 1145 (Table 32).
* Table: Surface items $SURFACEITEM:SURFACEID;FACEID;ENCLAVE 866;1139;0 868;1141;0 869;1144;0 869;1145;0 |
In the Faces table, all faces contained in the network are stored with their IDs. In this example, there are thus four faces (Table 33).
* Table: Faces $FACE:ID 1139 1141 1144 1145 |
In the Face items table, each face is allocated the IDs of the edges which define the face. As you can see in Table 34, the faces with the IDs 1141, 1144 and 1145 are squares each, as they are defined by four edges. Face 1139 however, is a pentagon with five edges.
* Table: Face items $FACEITEM:FACEID;INDEX;EDGEID;DIRECTION 1139;1;33136;0 1139;2;33137;0 1139;3;33138;0 1139;4;33139;0 1139;5;33140;0 1141;1;33145;0 1141;2;33146;0 1141;3;33147;0 1141;4;33148;0 1144;1;33160;0 1144;2;33161;0 1144;3;33162;0 1144;4;33163;0 1145;1;33164;0 1145;2;33165;0 1145;3;33166;0 1145;4;33167;0 |
The table Edges contains all edges which are required for the description of the face items. Each edge is defined by a start point and an end point, which bear the attribute names FromPointID and ToPointID in the table (Table 35).
* Table: Edges $EDGE:ID;FROMPOINTID;TOPOINTID 33136;9449;9450 33137;9450;9451 33138;9451;9452 33139;9452;9453 33140;9453;9449 33145;9458;9459 33146;9459;9460 33147;9460;9461 33148;9461;9458 33160;9473;9474 33161;9474;9475 33162;9475;9476 33163;9476;9473 33164;9477;9478 33165;9478;9479 33166;9479;9480 33167;9480;9477 |
In the Points table, all points are displayed which in turn define the edges. Each one contains information on the coordinates (XCoord and YCoord). This establishes the spatial reference of the surface to the network (Table 36).
* Table: Points $POINT:ID;XCOORD;YCOORD 9449;3456991.5413;5430055.0204 9450;3456991.5413;5430004.3885 9451;3457052.3873;5429991.7699 9452;3457070.0872;5430048.9542 9453;3457026.8560;5430057.9988 9458;3458808.0227;5431086.8027 9459;3458821.3171;5431061.4225 9460;3458848.5102;5431078.9469 9461;3458835.5180;5431101.9100 9473;3456956.4483;5430005.5296 9474;3456948.8422;5430060.3735 9475;3456887.1928;5430052.7674 9476;3456903.2057;5429996.7225 9477;3456896.8005;5430097.6033 9478;3456938.0336;5430071.1821 9479;3456961.6525;5430097.6033 9480;3456945.2393;5430125.2254 |
No intermediate points were generated in the example. The table is therefore empty (Table 37).
* Table: Intermediate points $EDGEITEM:EDGEID;INDEX;XCOORD;YCOORD |
