Tutorial 2: Digital Elevation Model

Create a Digital Elevation Model (DEM) from contours and point data using ArcGIS 10.x

Is any digital representation of the continuous variation of elevation over space. The DEM is a computer representation of the earth's surface, and as such, provides a base data set from which topographic parameters can be digitally generated. Through the use of ArcMap, provided that we have elevation data in the form of points or contours, we can manage to create a DEM. DEM data is usually in a raster format. To create a DEM, we use the Topo to raster tool. The Topo to raster tool can be accessed through ArcToolbox => Raster Interpolation => Topo to raster as shown in figure 1 below.

Figure 1: Topo to raster

After the Topo to raster tool has been opened, we will be provided with the screen as shown by figure 2 below.

Figure 2: Topo to raster

After we have completed setting up the required information as shown by figure 1 above and clicked the OK button, ArcMap will create the Digital Elevation Model for us. The produced raster will look like the one shown by figure 3 below.

Figure 3: Created DEM

The created DEM data can be previewed in Arc Scene in a 3D form. To do so, we will open the data in Arc Scene as shown in figure 4 below.

Figure 4: Previewing the DEM data in Arc Scene

When the DEM is added to Arc Scene, it would normally be displayed as a flat document as shown in figure 4 above. It view it in an elevated form, we will have to right click the DEM data on the scene layers shown in figure 4 above and thereafter go to properties as shown in figure 5 below.

Figure 5: Previewing the DEM on Arc Scene

After we have clicked on the properties option illustrated in figure 5, we will thereafter be provided with the screen as shown in figure 6 below.

Figure 6: Layer properties

We will set the elevation from surface as floating on custom surface and make sure that our DEM data has been specified, the next step is to specify the factor to convert layer elevation to scene units. We will set this option to custom and give it a value of 2 as shown in figure 6 above. We will complete by clicking on the OK button. After we have completed the step illustrated in figure 6 above, the elevation data will be displayed as shown in figure 7 below.

Figure 7: Displaying the DEM data in a 3D model

We can also use Arc Scene to have a 3D preview of the building of the area. This can be done by opening the layer in Arc Scene. After the layer has been added in Arc Scene, it will be displayed as illustrated by figure 8 below.

Figure 8: Previewing the buildings on Arc Scene

To have a 3D view of the data, we will again access the properties of the data as it has been illustrated by figure 5 above. After we have accessed the property window of the data, we will be provided with a screen as illustrated by figure 9 below.

Figure 9: Properties window for the buildings layer

After we have opened the expression builder, we will be provided with the expression builder and it will be displayed as shown in figure 10 below.

Figure 10: Expression builder

Using the expression builder, we will add three to the number of floors and multiply by three and thereafter click on the OK button to perform the expression and thereafter click on the OK button. The buildings will thereafter be displayed in a 3D form as shown in figure 11 below.

Figure 11: Buildings displayed in 3D

To preview the buildings in an elevated surface using the DEM data, we will access the properties of the buildings layer, and thereafter go to the base heights of the layer and set the DEM layer as the source of the base heights as shown by figure 12 below.

Figure 12: Setting the base heights

After the DEM data has been selected, we will click the OK button. The buildings will thereafter be displayed as shown in figure 13 below.

Figure 13: 3D model of the buildings

Using the same procedures, we will add the rest of the layers and the data will be displayed as shown in figure 14 below.