In the generation of the DTM, objects from the ground were removed. However, there were residual objects on the ground, such as short bridges, small buildings, embankments, etc., that were overlooked and could not be removed by TerraScan. In addition, there were areas on the DTM that didn’t have data, which may be due to ash clouds, turbulence, water bodies , etc. These residual objects should be removed and areas with no data should be filled in to have a good quality DTM.
An ArcMap plug-in tool developed by UP-DREAM, called ArcTeam, was used to edit LiDAR digital elevation models (DEM). The installation procedures of ArcTeam can be found in the USC Phil LiDAR 1 Manual. To see if ArcTeam is successfully installed, the Add-In Manager (click Customize in the main menu then go to Add-In) shows the ArcTeam Toolbar under My Add-Ins as shown in Figure 2.8.
By clicking Customize>Toolbars and checking the ArcTeam Toolbar, the toolbar will appear on the menu bar.
The ASCII files were first loaded into ArcMap using the ArcTeam Tool (LoadASCII tool). This also mosaicked the tiles and applied hillshading. It converted the elevation into Orthometric Height using EGM08 Geoid and set the projection to WGS 84 UTM Zone 51. In loading the ASCII files into ArcGIS, a layer named v_no_data_area was created that contains areas where there is no data. These areas were filled in using the FillDataGaps tool of ArcTeam. In removing residual objects in the DTM, an interpolation procedure carried out by the InterpolateRaster Tool of ArcTeam was performed. An example of an unedited DTM is shown in Figure 2 2, which portrays a small bridge not removed by TerraScan. In order to have a good DTM appropriate for flood modeling, this small bridge should be removed, otherwise the flood modeling software will interpret this as an obstruction to water flow. Figure 2 3 shows the DTM after editing in which the small bridge has been removed.