Creating a Terrace using Strings
This Tech Tip explains how to create a terrace from a cad drawing using strings.
Converting the drawing
The drawing must be included in the project.
File Menu › Edit Project
DTM with CAD lines showing proposed terrace
Terrain Mode
Strings Menu › String Creation › Polyline to String
The program will prompt:
Click on the polyline that must be converted.
|
String name |
Enter the name of the resultant string |
|
Zero height |
Select this option if you want the vertices of the
resultant string to have zero elevation. |
|
Fixed height |
Select this option if you want the vertices of the
resultant string to have a fixed elevation value. |
|
Interpolate on
surface |
Select this option if you want the vertices of the
resultant string to have an elevation interpolated
from a DTM surface. Choose which surface is to be
used from the dropdown list. |
|
Search distance |
Greyed out unless the 'Interpolate on surface'
option is selected. Choose a value at least double
the average distance between points on the
selected surface. |
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Constant to add |
Type in a value if you want the interpolated
elevation to have a further constant added or
subtracted. |
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Chainage interval
for arcs |
Greyed out for all functions other than 'Convert
Entities to String'. With this function you can
select an arc cad entity and have the string
coincide with the arc. For this reason a chainage
distance along the arc is needed. |
Press OK to accept any changes or Cancel to close the dialog losing the changes.
In this example we will create a string called terrace with a height of 82m.
Once the string has been created the drawing can be removed from the drawing and the string can be switched on in the Display Settings.
Settings Menu › Display Settings
Various options can be changed in the Display Settings for Strings.
Once the string has been created, the next step is to create a child string which will grade to the ground dtm at a slope of 1:5
Strings Menu › String Creation › Create Child
Click OK to continue.
The program will prompt:
The child string is created.
The next step is to convert the strings to dtm points.
Strings Menu › String Editing › String to DTM
The dialog indicates which string will be converted, if this is not the correct string, click OK, you will then be able to select the correct string.
Select Recurse children if you want the children of the chosen string to also be converted.
Once the string has been converted, the strings can be switched off in the Display Settings, we will also switch on the new dtm surface to show the converted points.
Settings Menu › Display Settings
Showing the new terrace, after the strings have been converted.
You can now view the terrace in 3D if required.
Terrain Menu › 3D View › View
Select the ground dtm surface and the new terrace surface, click OK to continue.
The new terrace shown in 3D.
 print friendly version
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