This Tutorial shows Routing Calculations. You learn about
opening a Project Data Set (*.minfo)
creating Texts automatically
computing a Routing
computing a Spreading
MensorGIS stores Project Data Sets in a proprietary XML Format, consisting of several XML Files (Menues „File-Open“/„File-Save“):
Configuration, i.e. Spatial Reference System, Limits, Layers and other (*cfg.xml);
Points, i.e. Point Features and all other Points (*pnt.xml);
Lines, i.e. Line Features and all other Lines (*lin.xml);
Areas, i.e. Area Features (*are.xml);
Texts, i.e. Text Features (*txt.xml);
Attributes, i.e. attributive Data (*att.xml);
Data Schema, i.e. Object Classes and their Attribute Definitions (*sch.xml).
Change of Data Properties is possible for (Menu „Edit“):
Colors (by Layer/by Object Class);
Point Size (by Layer/by Object Class);
Line Types (by Layer/by Object Class);
Areas Hatches (by Layer/by Object Class);
Text Properties (Color, Size, Layer, Visibility, Contents);
Layers (take all Properties from certain Object Class).
Topological Analysis is essential for GIS Functionality; Mensor GIS allows (Menu „Topology“):
to prepare for building up a Topology (Triangulation, Use all Points);
to create a Topology (Edges, Vertices, Faces);
to calculate a Routing (unweighted/weighted);
to calculate a Spreading (unweighted/weighted);
to calculate a Point Buffer (Topolgical Operators);
to calculate a Line Buffer (Topolgical Operators).
Menu „File - Open“
select „TopoTutorial.minfo“
Menu „Edit - Texts - Generate from Object Class“ or Button „TG“ -> Window „Create Text“:
select Object Class „* City“
select Attribute „NAME“
select Color „Black“
select Size „4“
select Layer „1“
press „Create Texts“
close the Window (OK)
Menu „Edit - Texts - Generate from Object Class“ or Button „TG“ -> Window „Create Text“:
select Object Class „- Street“
select Attribute „SPEED_CLASS“
select Color „Black“
select Size „4“
select Layer „1“
press „Create Texts“
close the Window (OK)
Menu „Topology - create Topology“
ignore the Warning on Area Objects (OK)
-> Message „Topology partially created!“ (18 Point-Point / 18 Point-Line / 30 Line-Line)
Street Classification means that not the shortest Way, but the fastest Way is computed.
Menu „Topology - Routing“ -> Window „Routing“ is shown:
press Start -> select Node at A -> P 1
press Destination -> select Node at D -> P 5
select Attribute „>no Attribute<“
press „Calculate“
-> Highlighted Path: look at length and time (press „Redraw“ to redraw)
-> in Project's /bin/Debug Directory open „Routing.html“
now select Attribute „SPEED_CLASS“
press „Calculate“
-> Highlighted Path: now longer, but less time (press „Redraw“ to redraw)
-> in Project's /bin/Debug Directory open „Routing.html“
close the Window (OK)
Menu „File - Import - GPX“
select „Ergoldsbach.gpx“
answer the Question on Identity Check with „Yes“ (important!)
-> 1 Object Class gets created (Lines): Streets of OpenStreetMap
Menu „Topology - Use all Points“
answer the Question with „Yes“
-> 1450 Points are available
Menu „Topology - create Topology“
ignore the Warning on Area Objects (OK)
-> Message „Topology partially created!“ (3052 Point-Point / 3052 Point-Line / 3220 Line-Line)
Menu „Topology - Spreading“ -> Window „Spreading“ is shown:
press Start -> select a Node of the Street Network
enter Distance in km -> maybe 0.3
select Attribute „>no Attribute<“
press „Calculate“
-> Highlighted reachable Points (press „Redraw“ to redraw)
-> in Project's /bin/Debug Directory open „Spreading.html“
close the Window (OK)
A Topological Model is an abstract Model describing the Connections between Objects, indepently of the exact Geometry.
In a Topology Point Features are called Edges, Line Features Vertices and Area Features Faces.
The Relations between these (Edges, Vertices and Faces) can define different Models depending on the use:
e.g. Edges and Vertices can build a Network of Streets or Pipes; so each Vertice will have a Resistance;
Such a Resistance could be simply the Distance between the two Edges;
If there are different kinds of Streets or Pipes the Resistance could be defined as Distance times a Weight Factor describing the Velocity;
So we have classified Street Network, in which not the shortest but the fastest Way can be computed.
There are also different kinds of Analysis: Network Analysis, Buffering, etc.
A Network Analysis can find the fastest way between to Edges or all Edges which are reachable from one Edge in a given Time and so on.
The Routing Algorithm finds an optimized Way between two Points; in MensorGIS the Dijkstra Algorithm is used for this problem.
The Spreading Algorithm finds all reachable Points within a maximal Distance; in MensorGIS the Dijkstra Algorithm is used for this problem.
Buffering allows to define an Area around a Point Feature (Point Buffer) or on both sides of a Line Feature (Line Buffer).
Using Topological Operators you can find out which other Features lie inside, partly inside this Area or only touch this Feature etc.
There are many Topological Operators; MensorGIS implements only two of them: "overlaps" and "covers".
MensorGIS uses an internal Topology between the Features at any time; but this Topology is only designed to manage the Features;
So, to compute Topological Analysis the Analysis Topology has to be built up at first; but this Topology needs more Memory.
If Memory is not sufficient, call the „Extras - Set Preferences - Redimensioning“ Menu and change the Topo(logical) References to a higher number.
You may also use Data Sets with PolyLines only. At first you must read in such a Data Set answering the Option "Identity Check" with "YES". Then the Menu „Topology - Use all Points“ allows to get the Background Points for Use in the Creation of Topology.
MensorGIS Version 1.1.8, 2012/11/08