This Tutorial shows a Topographic Mapping. You learn about
setting Reference Systems and importing CSV Data
changing the Attributes of an existing Object Classes
creating a new Object Class and its Attributes
computing Geodetic Transformations for Input of measured Data
generating Height Contour Lines and Cartographic Layout
the Main System for the Project Data Set which is visualized in the Plot Area;
the Import/Export System for Data to be read from a File or to be written into a File.
to create new Object Classes with user-defined Attributes;
to import Object Classes via standardized XSD (Xml Schema Definition) Format of GML2 (GML Schema);
to import Object Classes via internal XML Schema (*sch.xml);
to assign Object Classes to Geometry Objects (e.g. from CAD);
to edit attributive Information (Edit Function);
to query attributive Information (Attributive Query).
the Helmert Transformation with 4 Parameters;
the Affine Transformation with 6 Parameters.
A typical Cartographic Functionality is Generation of Height Contour Levels (Menu „Height Data“):
the Information of a certain Object Class can be selected (Coordinates and one Attribute containing the Heights);
different Interpolation Methods are available (NearestNeighbourhood/InverseDistance/InverseSquaredDistance);
after processing the Contour Levels the Number of Steps and the Contrast can be adapted (Threesholding/Scaling).
Import Fixed Points from national projected Coordinates on Central Meridian 12 to the same national projected Coordinates on Central Meridian 9.
Editing Attribute Names and Creating a new Object Class.
Visualizing Text from Attribute Values.
Import Mapping Measurement Points from local Polar Coordinates to the national projected Coordinates on Central Meridian 9.
Computing Height Contour Levels and editing Cartographic Layouts.
Menu „Reference Systems - Main System“ -> Window „Main System“:
select Type „projected“
select Projection „GK(D)“ (Germany)
type in Central Meridian „9“
select Unit „Meter“
select Datum „Bessel/DHDN“
press „Save“
Menu „Reference Systems - Import/Export System“ -> Window „Import/Export System“:
select Type „projected“
select Projection „GK(D)“ (Germany)
type in Central Meridian „12“
select Unit „Meter“
select Datum „Bessel/DHDN“
press „Save“
There is one General Projection for the whole World called UTM (Universal Transversal Mercator).
Each Country of the World uses its own local (plane) Projection. Some of these Projections are available in MensorGIS.
The UTM Projection and the Projections of some Countries use different Central Meridians for different Parts of the Country.
The States of the USA use different Projections with different Central Points indicated by I(dentity) Codes.
When you select a certain Projection the default Central Meridian/empty ICODE, the default Units and default Datum are shown.
According to the Data to be used you have to change these Elements; especially be aware that some States use Meter and some use Feet as Unit.
If you want to use a local (plane) Projection as Main System you should set this System appropriately before importing Data Sets.
Menu „File - Import - CSV Data“
select „CT_FixedPoints.dat“
answer the Question on Identity Check with „No“
-> the Window „Import CSV Points“ is shown
select the empty Separation Character (3rd Alternative) and press „Start Prescan“
-> 4 lines are shown on the left side
in the ComboBox over the right side select „Create new Object Class“
-> 4 lines are shown on the right side
pick on the left side the 5-digit Point Number (1st line) and on the right side „attr1“ and press „Add“
-> a line appears in the DataGridView below
pick on the left side the Easting beginning with '4' (now 1st line) and on the right side „X (Long/Easting)“ and press „Add“
pick on the left side the Northing beginning with '5' (now 1st line) and on the right side „Y (Lat/Northing)“ and press „Add“
pick on the left side the Height (now 1st line) and on the right side „attr2“ and press „Add“
-> 4 lines are now in the DataGridView below
let the Options as they are (Scaling Factor 1.0 / don't Ignore First Line)
press „Start Import“
-> the Message Text says „7 Points imported“
press „OK“ to close this Window
Menu „Data - Schema - Schema Tree View“
-> the Window „Schema Tree View“ is shown
click on the '+' Sign left of „CT_FixedPoints“
-> the Attributes 4 are shown
click on the „attr1“
-> below you can edit this Attribute; delete the old name and type in 'No'
press the Button „Save“ to save the changes for this Attribute
click on the „attr2“
-> below you can edit this Attribute; delete the old name and type in 'Height'
press the Button „Save“ to save the changes for this Attribute
close the Window (OK)
Menu „Data - Schema - New Object Class“
-> the Window „New Object Class“ is shown
choose the Graphic Type „Point“ and type in the Object Class Name „MapMeasurement“
then type in the first Attribute Name: 'No' and press the Button „Add Attribute“
-> a line appears in the DataGridView below; press the Button „Clear“ to reset the Input
then type in the second Attribute Name: 'Height' and press the Button „Add Attribute“
press the Button „Save“ to create the new Object Class and its Attributes
-> a MessageBox says that the Object Class „MapMeasurement“ was saved
close the MessageBox and then the Window (OK)
Attributive Data make GIS Data from CAD Data.
Its usual to set up a Data Schema containing Object Classes with their Attributes.
The Attributes can have different Data Types (Numeric, Text); for simplification all Attributes of MensorGIS are Texts (Strings).
For the Attributes there may be Restrictions: e.g. a Numeric Area in which they are valid or distinct Textual Terms;
The Object Class Creator and the Schema Tree View of MensorGIS let you enter such Boundaries (Minimum and Maximum Values).
More efficient Implementations use Databases to hold the Data; MensorGIS wants more Transparency to see how it works.
The Shape File Format (*.shp) uses a depreciated Version of the DBase Format (*.dbf) to store the Attributive Data;
In an GML(2) File (*.gml) the Attributive Data are enclosed in the Objects; but there must be a separated Data Schema File (*.xsd).
In GIS Systems the Query of Attributive Data is usually done by SQL (Structured Query Language);
The Attributive Query Window simulates such a SQL Query with all typical Elements:
Select Clause, From Clause, Where Clause, Comparation Operator, Attribute Value, optional second Where Clause via Logical Operator.
Menu „Edit - Texts - Generate from Object Class“
-> the Window „Create Text“ is shown
select Object Class „* CT_FixedPoints“
select Attribute „No“
select Color „Red“
select Size „4“
select Layer „1“
press „Create Texts“
close the Window (OK)
Open the File „CT_IdentPnts.txt“ (in the MensorGIS\bin\Debug\Data Directory) with any Text Editor
-> you see 7 Identical Points, the Point Numbers are identical to the just visualized ones
Menu „Surveying - Free Stationing / Measurement“
-> the Window „Free Stationing / Measurement“ is shown
choose the Coordinate Type „Polar“
press „Pick Fix.Pnts.“ -> in the Graphics Plot Area select 52204 -> the GIS System Coordinates are shown
for this Point copy the Horizontal Distance s and the Direction Angle/Bearing t from the Text File into the according TextBoxes
press „Add Pnt.“ -> a line appears in the DataGridView below
do the same for the next 3 Points
when all 4 Points are in the DataGridView choose Transformation Type „Affine“
press the Button „Calculate Parameters“ -> the Transformation Parameters are shown (Shift Vector, Rotation Angles and Scaling Factors)
also the Residues are shown in the last two Columns of the DataGridView, they are given in [cm]/[cft] and shold be near Zero.
if not so, check Numbers in the DataGridView. By Clicking two times (no Double Click) into a Field of the DataGridView you can edit it.
press „From File ...“ -> select „CT_PolarMeas1.txt“ -> Polar Measurement of 284 Points including Number and Height get shown
press the Button „Calculate New Points“ -> the GIS System Coordinates are shown in the last two Columns of the DataGridView
choose the Object Class „*MapMeasurement“ in the left ComboBox below the DataGridView
choose the Attribute „No“ in the upper right ComboBox and the Attribute „Height“ in the lower right ComboBox
choose the Color „Black“ in the Toolbox of the MensorGIS Main Window
press „Save“ -> the 284 Points including Number and Height get imported into the Project Data Set
close the Window (OK)
Remarks on Basic Survey Calculations:
In Surveying usually the (plane) Coordinate System differs from the mathematical one: X is Northing and Y is Easting;
Because MensorGIS was developed as a hybrid CAD and GIS Program, the internal Coordinate System is defined as in CAD Systems: x to the right, and y up.
Routines which belong to the Graphics Plot Functionality of MensorGIS use the mathematical CAD System (ModulePlotFunctions);
whereas Routines which belong to the Survey Functionality of MensorGIS use the Survey and GIS System (ModuleGeodFunctions);
when calling Routines of the other part, these different Definitions must be kept in mind.
The Windows of the Basic Survey Calculations allow an Interaction to the Objects in the Plot Area of MensorGIS:
using the Buttons beneath the Coordinate Fields you may pick a Point Object in the Plot Area to take its Coordinates into the Window;
the Save Button beneath the New Point's Coordinate Fields creates a new Point Object with these Coordinates in the Plot Area.
Menu „Data - Schema - New Object Class“
-> the Window „New Object Class“ is shown
choose the Graphic Type „Line“ and type in the Object Class Name „ContourLines“
then type in the first Attribute Name: 'No' and press the Button „Add Attribute“
-> a line appears in the DataGridView below; press Button „Clear“ to reset the Input
then type in the second Attribute Name: 'Height' and press the Button „Add Attribute“
press the Button „Save“ to create the new Object Class and its Attributes
-> a MessageBox says that the Object Class „ContourLines“ was saved
close the MessageBox and then the Window (OK)
In the Tool Bar of the MensorGIS Main Window choose „Black“ as active Color
choose Menu „Height Data - Compute Contour Lines“
-> the Window „Height Contour Lines“ is shown
as Height Information select Object Class „MapMeasurement“
and select Attribute „Height“
as Destination select Object Class „ContourLines“
and select Attribute „Height“
select Interpolation Method „Inverse Distance (9)“
choose in the ComboBox for the Intervall 2.5 Meters
choose in the ComboBox for the Raster Resolution 5 Meters
choose Mode „Preview“ to test if Intervall and Resolution are appropriate
press Button „Calculate“ -> violet non-permanent drawing
choose Mode „Store“ to save the Height Contour Lines
press Button „Calculate“ -> Points and Lines get saved into the Project Dataset
the Percent Number/Progress Bar show the State of computation (if you want to stop the computation then press „STOP“)
when computation is finished the Height Contour Lines get displayed
a Result Message says how many Contour Lines have been generated
close the Window (OK)
Remarks on Interpolation Models:
There are different kinds of Interpolation Models: Weighted/Unweighted, Geometrical/Statistical, etc.
Usually an Interpolation is done by a Triangulation of the Height Points and in the resulting Triangles a certain Interpolation Model is used.
Geometrical Models are e.g. (Bi)Linear Interpolation, (Bi)Quadratic Interpolation; a Statistical Model is e.g. Collocation.
The problem of using Triangulation is that only inside the Tringulation Network an Interpolation can be done; outside it would be an Extrapolation.
Geometrical Models can become inaccurate in Extrapolation Areas; Statistical Models are more stable.
MensorGIS implements different kinds of Statistical Models to be able to always get a Rectangluar Area around the Height Points.
These Models are of different quality: Nearest Neighbourhood is the simplest and not to accurate; the Inverse Distance Models are more exact.
Threesholding the Steps and Scaling the Contrast are Terms used in Digital Image Processing; here they are used to adapt the result to your needs.
The Height Contour Lines are shrinked to the Convex Hull of the Height Points; to compute the Convex Hull, Andrew's monotone Chain 2D Algorithm is used.
The (not zoomable) Height Contour Level Raster can also be exported using Menu „File - Export - SVG“.
The Generation of Height Contour Lines needs a regular Grid of Raster Points which is interpolated from your Height Points.
The (zoomable) Height Contour Lines can be treated as a common Object Class of Type "Line".
Menu „Cartography - Style Editor“
-> Window „Style Editor“
select Graphics Type „Point“
choose a Graphics Style (Type and Size) from the next ComboBoxes
choose a Graphics Color from the next ComboBox
select Target of change „Object Class“
select Object Class „CT_FixedPoints“
select where Attribute „>WHOLE_CLASS<“
press „Change“
close the Window (OK)
MensorGIS Version 1.1.6, 2012/09/19