EM.Terrano Tutorial Lesson 5: Modeling Irregular Terrain

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Tutorial Project: Modeling Irregular Terrain
Terrano L5 Fig title.png

Objective: In this project, you will construct an irregular terrain surface to serve as the ground of your propagation scene.

Concepts/Features:

  • Wizard
  • Terrain Surface
  • Impenetrable Surface
  • Material Properties
  • Transmitter Set
  • Receiver Set
  • Terrain Elevation
  • Received Power Coverage Map

Minimum Version Required: All versions

'Download2x.png Download Link: EMTerrano_Lesson5


What You Will Learn

In this tutorial you will use a wizard to create a plateau terrain profile. You will learn the special properties of terrain objects affecting the elevation of objects above them.

Getting Started

Open the EM.Cube application and switch to EM.Terrano. Start a new project with the following attributes:

Starting Parameters
Name EMTerrano_Lesson5
Length Units Meters
Frequency Unit GHz
Center Frequency 1 GHz
Bandwidth 1 GHz

Creating the Plateau Terrain Profile

For this tutorial lesson, you will use a wizard to create a large terrain profile in the project workspace. Click on the Plateau Terrain Wizard PlateauTerrainWizardIcon.png button of the Wizard Toolbar or select the menu item Tools → Propagation Wizards → Plateau Terrain. A large plateau terrain object appears with a random rough surface.

EM.Terrano's wizard toolbar.
The geometry of the default plateau terrain created by the wizard.

Just like impenetrable and penetrable surfaces, a terrain surface is a special type of object in EM.Terrano that is used to model non-flat or irregular ground. Terrain objects are grouped together under Terrain Surfaces node of "Physical Structure" in the navigation tree. Open the variables dialog and see all the variables defined by the wizard for the plateau terrain scene. Edit and change the definition of the following variables:

Variable Name Original Definition New Definition
area_size 200 400
height 10 20
slope 0.1 0.25
The variables dialog showing the new parameters of the plateau terrain scene.
The geometry of the plateau terrain after changing some of its parameters.

Constructing a Block of Buildings

Create a default impenetrable surface group in the navigation tree with brick composition. Then, under "Block_1" draw a box object withe following parameters:

Object Geometry Block Group Surface Type Material Dimensions Location Coordinates Rotation Angles
Box_1 Box Block_1 Impenetrable surface Brick 40m × 80m × 30m (-200m, -300m, 0) (0°, 0°, -30°)

Note that the box object has been rotated about its local Z-axis by -30°. Select Box_1 and create an array object from it using the following parameters:

Array Object Parent Object X Count Y Count Z Count X Spacing Y Spacing Z Spacing
Box_1_Array_1 Box_1 3 3 1 120m 150m 0
The geometry of the plateau terrain with a block of buildings.

The array, by default, has a 3 × 3 rectangular grid. You can also give additional rotation to the array grid to create more complicated lattice topologies. Open the property dialog of the array and enter

The property dialog of the box array object showing the additional array rotation.
The geometry of the plateau terrain with a block of buildings after the additional array rotation.

A terrain surface is a tessellated surface object, which consists of a large number of triangular cells. View the mesh of your physical structure to get a sense of its geometrical complexity.

The facet mesh of the propagation scene with the plateau terrain and buildings.

Defining the transmitter & Receivers

For this tutorial lesson, you will define two base location sets called "BasePointSet_1" and "BasePointSet_2" with the colors blue and orange, respectively. Under "BasePointSet_1", create a single point object for the transmitter. Under "BasePointSet_2", create an array of base points for the receiver set according to the tables below:

Part Object Type Object Group Group Color Dimensions Coordinates
Point_1 Point Base_Point_1 Blue N/A (120m, 120m, 10m)
Point_2 Point Base_Point_2 Orange N/A (-390m, -390m, 1.5m)
Array Object Parent Object X Count Y Count Z Count X Spacing Y Spacing Z Spacing
Point_2_Array_2 Point_2 157 157 1 5m 5m 0

Define a new default transmitter set associated with BasePointSet_1 and a new receiver set associated with BasePointSet_2. In the new transmitter and receiver dialogs, make sure to check the boxes labeled Adjust Tx Set to Terrain Elevation and Adjust Rx Set to Terrain Elevation, respectively.

Adjusting transmitters to terrain elevation in the new transmitter dialog.
Adjusting receivers to terrain elevation in the new receiver dialog.

At this time, your project workspace must show a scene like the figure below.

The propagation scene with the transmitter and receivers adjusted to the terrain elevation.

Running an SBR Analysis of the Propagation Scene with the Plateau Terrain

Run an SBR analysis of your plateau terrain scene and visualize its received power coverage map. You can see from the figure below that the upper portion of the plateau obstructs the rays from reach the valley region. As a result, the buildings do not get any reception at all.

The top view of the received power coverage map of the plateau terrain scene with the transmitter base at X = Y = 120m.

To improve the reception, you can bring the transmitter to the edge of the plateau. Keep in mind that to move a transmitter or receiver, you need to move their associated based point sets. Open the property dialog of "BasePointSet_1" and change the coordinate to X = Y = 40mm. Keep the original Z-coordinate of 10m. Now run a new SBR analysis of the scene and visualize its coverage map. You will see that the valley region now gets considerable reception. The reception can be further improved by raising the height of the transmitter above the terrain surface.

The top view of the received power coverage map of the plateau terrain scene with the transmitter base at X = Y = 40m.

Changing the Terrain's Surface Roughness Statistics

Among the variables that the wizard initiated are root-mean-square (RMS) height and correlation length of the rough surface. The terrain surface object is assumed to have an over offset elevation that is represented by the variable called "elevation". Open the variables dialog and change the definition of the following parameters:

Variable Name Original Definition New Definition
elevation 0.5 2
rms_height 1 1.5
correl_len 10 5
The variables dialog showing the new parameters of the plateau terrain scene.

As you can see from the following figure, the new roughness statistics make the terrain more rugged than before.

The geometry of the plateau terrain after changing its surface roughness statistics.

Run an SBR analysis of the new more rugged terrain scene. Note that this is a relatively large computational problem. The simulation output window reports some of the simulation parameters:

SBR Simulation Parameter Value
Total Number of Facets 67,294
Total Number of Edges 48,809
Total Number of Receivers 24,649
Total Number of Transmitted Rays 64,980

At the end of the SBR simulation, visualize the coverage map. Note how the more rugged surface terrain has caused significant wave diffusion throughout the scene.

The top view of the received power coverage map of the plateau terrain scene after changing its surface roughness statistics.

 

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