Graph building |
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After forming the list of marked objects the dialog of building the graph is displayed.
Input of a graph map's name By default, the map of the graph is created in Graph subdirectory of an input map. Map name of the graph coincides with the name of the original map with the addition of the prefix graph. If desired, the name of a created map of the graph can be changed by pressing the button The classifier road25.rsc which is delivered as a part of the GIS Panorama is specified by default. If on the basis of road25.rsc another classifier was created, then you need to select it by clicking on the button - additions of the preset list of types of roads in case the graph is built by non-standard for topographic maps the objects of the road network; - additions of the list of admissible semantics for edges in case you want to filter by these semantics at route search.
Group «Options» Matching tolerance determines on what maximum distance it is considered that two points are located in one place. Change of the tolerance allows correctly to build the network in the case when the roads are insufficiently precisely agreed upon in the places of crossroads. The tolerance value is entered in meters on the ground. When the mode is set Save link with objects of the original map, into predefined semantics of edges and network nodes the data are put for their link with objects from which they are constructed. Enabling of this mode increases the size of a map, but allows to find parental object of an edge and node on the original map. This possibility is used for displaying the list of names of streets and roads at building a route. By default the mode is enabled. At creating a map of the graph the selected linear, point and vector objects are used. From the selected linear and vector objects the edges are created. There is no necessity usually to mark point objects, because nodes in places of crossings of roads are created automatically. However there can be a necessity to copy into nodes the semantics from the point objects located in these places. For example, to write down into nodes the names of railway stations, when you build a graph of the railways. In this case before a calling the dialog, together with roads it is necessary to mark stations and in dialog to choose semantics, copied from stations into nodes. At building a map of the graph the nodes will be created on the location of stations, even if in this place there is no crossroads.
Group «One-way road» By default, the roads are two-way. If there are one-way roads, then for their identification it is necessary from the list of Semantics to choose the semantics which is only in roads with one-way traffic. After semantics choice it is necessary to enter the value corresponding to roads with one-way traffic (or to choose from the list for enumerated semantics). For roads with semantics specified in the field the Forward direction of a digitizing should coincide with the permitted direction of movement. Accordingly, roads with the value of semantics entered into the field Backward, are identified as roads with the one-way traffic, which direction is oppositely to a digitizing direction.
Group «Speed» Speed of movement on road is necessary for search of a route with the minimum time of travel. It is possible to determine the speed by entered it into the table of speeds by road's type or having specified semantics in which it is written down. In the table of speeds the speeds by default are entered for each type of roads from which edges will be created. At the first starting the dialog for all roads the speed in 60 km/hour is set. If in any road there is semantics chosen from the list From semantics, then value of speed for this road is set from this semantics. Thus, the speed of semantics has a higher priority than the default speed entered in the table. In addition to speeds by default in the table the road type, assigned to edges is entered. The road type is used further for a filtration of roads at route search. The type of road for topographic maps is set automatically by object code. When you build a graph by non-standard classifiers for topographic maps you will need to select the road type manually. To do this, click in the corresponding cell of the table and select the road type from the dropdown list. The list of roads types is set from the list of admissible values for semantics «Type (class) of road» in the chosen classifier.
Group «Semantics that are copied to the network edges» In this list the semantics are chosen, which are transferred from road into edges which are created by this road. These semantics are used at a filtration of edges by semantics at route construction. If semantics is valid for edges it is displayed by black color. Invalid semantics is shown by red color. If an invalid semantics is selected for copying into the edges, it will be recorded into edges, but filtering by this semantics at the route search will be impossible. Filtering by semantics greatly increases the search time of the route, because it requires reading of edges semantics from disk. Besides, copying the semantics considerably increases the size of a graph map. Therefore, if it is not planned to filter edges of the graph by semantics it is not recommended to copy semantics into network edges.
Group «Semantics that are copied to the network nodes» At present into network nodes it makes sense to copy only semantics «Name» (code 9). This semantics is used in the traveling salesman problem in a mode of loading names of nodes from a text file. If it is not planned to apply the traveling salesman problem in this mode, then to copy semantics into nodes it is recommended to reduce the size of a graph map. If at calling a dialog on the original map there are no marked point objects this table is not shown.
Building a graph After setting the parameters a creating of graph map is started by the Build button. The name of a processing stage and percent of performance are shown in group a Processing status. At construction of the graph the following steps are consistently carried out: - loading objects; - search of edges and nodes; - determining the network number; - recording of edges; - recording of nodes.
To cancel the building process, click on the Cancel button. After creation the graph map is added to the original map, and after creating a file the graph will be ready to solving search problems. Nodes and edges which have different value of semantics "Network number" are displayed by different colors. It simplifies search for mismatch places of network nodes leading to creation of several networks non-connected among themselves. |
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. Change of the classifier may be required for: 