This section will guide how to load a satellite geo-referenced map from Google Earth to cover the surface of a DEM (topo) in 3D View of EFDC_Explorer 10.

This guidance will take the demo model DM-13 as an example because it is available on EEMS resources. The instruction is mostly presented in the EEMS 3D View.

Generate DEM file (*.tb2)

Load the DM-13 model, open the 2DH View, select Generate DEM option from the Layer Controlas shown in Figure 1.

Figure 1. Generate a DEM option from Layer Control in 2DH View.

Once the option is selected, the Generate DEM form will appear as shown in Figure 3. From this form, the user click on Add File then browse to the digital elevation data file (terrain*.xyz) from Data folder. Once loaded, the coordinates of the Lower-Left and Upper-Right points will be updated as well as the Cell Size and Number of Cells, the user can change the Cell Size then click on the Calculator symbol to update the Number of Cells and vice versa. the more number of cells the higher resolution of the DEM file. The output format for the generated DEM files is TB2, click the Generate DEM button to start generating DEM file.

Figure 3. Generate DEM form.

Once, the Generate DEM button is selected, the Export DEM form is displayed as shown in Figure 4. Enter a name in the File Name (e.g Generated DEM), select the folder directory to store the file then click Save button as shown in Figure 4. When DEM file generation done, a informing message will be popped up as shown in Figure 5. Click OK button to exit the form.

Figure 4. Export DEM to a file.

Figure 5. DEM generated completed.

Load a DEM file in 3D View

Open the 3D View, click the Import External Layer in the Layer Control.  The Open External Layer form will be displayed. Select the DEM data file from drop-down list next to the File Name box as shown in Figure 6. Select the DEM file then click Open button. The DEM layer will be added to the Layer Control and displayed as Figure 7.

Figure 6. Import DEM file.

Figure 7. DEM displayed in 3D View.

The user can adjust vertical exaggeration to having a better view by changing the Vertical Scale Modifier in the form of 3D View Settings by RMC on the legend as shown in Figure 8. to set the DEM’s properties by RMC on this layer in the Layer Control, then select Properties option as shown in Figure 9.

Figure 8. 3D View Settings.

Figure 9. DEM properties.

Figure 10. DEM properties.

Figure 10 shows DEM Layer Properties form. There are a number of options from this form as described below:

General frame

Color Ramp frame

3D View Options frame

Use Overlay Image

This option allows to use geo-referenced map (e.g Google satellite image) to cover the surface of the DEM. Checked on box then click Browse button to browse to the geo-referenced image as shown in Figure 11 then click Open button and result is shown in Figure 12.

DEM Info: display general information of the DEM file as DEM size, cell size, X, Y and Z range.

The Convert Height allows to convert height of the DEM from the current unit (e.g meter) to other unit (e.g foot). When this option is selected, the DEM Height Conversion form will appear as shown in Figure 13. Click the Convert button on this form then click the OK in the Figure 10 to implement conversion. The new color ramp range for DEM will be updated on the legend.

The Flip button allows to adjust the grid fit to the DEM.

Figure 12. Open Overlay image.

Figure 12. DEM covered with a satellite image.

Figure 13. DEM height conversion.