MAPPER - applications

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Contouring

Description:
The contouring module is an application of the Mapper programme and it's used to triangulate topographic profile's elements in order to obtain contour lines or a surface composed of irregular triangles. Contour lines are defined on the basis of triangulation, including terrain's discontinuity lines. Contouring lets you easily find a collison of incorrect elements from the point of view of terrain's numeric model construction (e.g. crossing of two lines in different heights) and by that it's a perfect control tool.
Active image elements are read for a triangulation, but they can also be read from the attached reference files.

Run:
Select the Contours button in the DTM line

or enter AL=TRIANGULATION in the commands line

See:
Contouring - Options
Contouring - checking DTM errors

Dialogue:
Once you run an application a dialogue opens where you can select elements used for triangulation and results definition.
Application uses information included in a text file in TRI format to select elements. If there is no file selected with

button, image elements will be used for a triangulation

Display

displays contour lines in a temporary reference image

Insert

inserts elements to an active image

Triangles

generates triangles

Edges

generates triangles' edges

Errors

finds errors

Contours

generates contour lines

Options
Operation:
To run contouring select Triangulation button or enter AF=TRIANGULATION,PROCESS in the commands line.



Contouring– Options

You can modify elements, created triangles or contour lines in the process of triangulation and generation of contour lines using the options.
Select Parameters to go to advanced options of generating contour lines Contouring parameters.

They let you adjust the best run of generated contour lines possible depending on terrain's characteristics (diversification).

Elements modification:
Limit Edges: maximum length of a section being a forcing element in triangulation (breakline). Dividing long elements we avoid long side triangles.

Triangles modification:
Max Triangle Area: maximum size of a triangle. If a triangle's area is larger it has an additional point introduced in the centre, to take part in another triangulation. It makes a surface smoother but it is more time consuming due to need of a multiple triangulation.

Contour lines modification:
Long Lines: contour lines are created as a sequence of vertices. Otherwise, a contour line is broken every 50 vertex, and it's significant for the later edition in the MicroStation programme.

Break on Roads: Breaks contour lines on edges being type 1 breaklines, introduced into a relevant element of a TRI file.

Operations List (options described below): adding consecutive operations to a list you may obtain modifications of contour lines being created.

NOTE !!
All the theoretical examples of values presented below depend on terrain configuration; make sure you compare results of different contour lines generation options so that they correspond as much as possible with the real terrain.

Delete points:

Deletes points if they make sections shorter than a given parameter - 10m in this example.

Insert points:

Inserts a point if a section of a created contour line is larger than a given parameter.

Faulkner:

Reduces number of vertices so that a shape of contour line is as accurate as possible.

Bezier:

Contour line will be generated as a broken line curve shaped. Distance between points on direction lines results from division of a contour line section by the Divisor, and a curve will be approximated thanks to number of vertices resulting from the Delta parameter.

Waterlines:

If a contour line breaks on a 2 type breakline, an arc of a given radius is modeled in that place.

Roads:

If a contour line breaks on a 3 type breakline, and then a contour line section comes which is connected with a 3 type breakline, half arcs of a given radius are modeled on these two breaklines.


Contouring – TRI Format

TRI 3
COUNTOURS
1.5;2
1;60;1;0;0
4;61;4;1;0
EDGES
63;1;0;0
TRIANGLES
64;2;0;0
ERRORS
5.0
64;3;0;3
ELEMENTS
-;-1;-1;-1;-1;
+;4;130;2;0;0;SUPPORT WALL
+;4;133;0;0;0;ROAD
+;9;200;0;0;0;BREAK LINE
+;9;201;-1;-1;0;

Definitions description:

TRI3	File caption

COUNTOURS

1.5;2

Two types of contour lines will be generated; a full contour line will be drawn every 1.5 m and a broken contour line every 6 m

1;60;1;0;0

Contour line will be introduced every 1.5m; LV=60, CO=1, ST=0 and WT=0

4;61;4;1;0

Contour line will be introduced every 6m; LV=61, CO=4, ST=1 and WT=0

EDGES

Triangles edges

63;1;0;0

LV=63, CO=1, ST=0 i WT=0

TRIANGLES

Triangles filling will be as follows and the edges as in the EDGES section

64;2;0;0

LV=64, CO=2, ST=0 i WT=0

ERRORS

Circles with errors

5.0	Radius of an error signalling circle

64;3;0;3

LV=64, CO=3, ST=0 i WT=3

ELEMENTS

Begining of a definition of elements used in triangulation. Subsequent definitions turn import of appropriate elements for triangulation on or off

-;-1;-1;-1;-1;

No elements will be read

+;4;130;2;0;0;WALL

Read elements of the following parameters LV=4, CO=130, ST=2 and WT=0, and breakline type =0

-;4;133;0;0;0;ROAD

Exclude elements of the following parameters LV=4, CO=133, ST=0 and WT=0

+;9;200;0;0;0;BREAK LINE

Read all elements of the following attributes LV=9, CO=200, ST=0 and WT=0

+;9;201;-1;-1;0;

Read all elements of LV=9 and CO=201 independently of lines style and width

Comment:

+

addition to a set

–

exclusion from a set

L,C,S,W

elements attributes where – 1 means that given attribute is not covered

B

breakline type, it defines mode of generating contour lines on its edges