Generating digital terrain

Product(s): OpenFlows FLOOD
Version(s): 10.02.01.01

Overview

This article will cover how to generate digital terrain based on pre-existing XYZ data

Method

OpenFlows FLOOD includes a powerful tool for the generation of digital terrain grid data files. In our case, we will generate a digital terrain file based in the existing XYZ data file previously loaded:

  • Select the Toolbox, and then use the “Grid Data” -> “Create Grid Data from XYZ Points” tool.

  • Double click the tool to open it, as shown in the next figure (be aware that the map layer “grid.grd” was unchecked in the “visible” option):

Figure 1 – Create Grid Data

 

We will now construct the topography with the following options indicated in the following table.

Parameter

Value

Description

Grid

Grid

The grid which is to be used to create the grid data.

XYZ Points

DTM_xyz

The point dataset(s) which are to be used to fill the grid. In this example we only have one, but you can use multiple XYZ files.

Polygons (…)

n/a (default)

The polygon(s) which define non compute areas (water bodies in the case of MOHID Land). The model will not compute any values in the cell covered by these polygons.

Buffer %

10% (default)

Offset from the grid, in percentage, of the maximum distance from the “XYZ Points” are considered when using interpolation algorithms.

Fill Value

-99.0 (default)

The value to be attributed in non-compute areas. You should not change this value unless you have a specific reason for.

Z value in NCA

Leave uncheck

If you want to consider a specific height in the non-compute areas for the interpolation process near the land-water interface.

Interpolation

Average Z within cell

The interpolation method you want to use. If the density of points is smaller than the number of grid cell (not every cell contains a XYZ Point), then Triangulation is the recommended option.

Grid Data

C:\OpenFlows FLOOD Quick Start Guide\Projects\New Domain\General Data\Digital Terrain\DTM.dat”

The name of the file which will be created. It’s recommended to place this file inside the folder General Data\Digital Terrain of your project domain.

 

After filling all data, choose the process button ( ) to generate the topography. This process is finished when you see the following status message:

Figure 2 - Status message of the Construct Grid Data Tool

Close the status message and the tool window (using the x). Your main window should now like the one in the following figure.

Figure 3 – Visualizing Grid Data (Digital Terrain model)

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