There are three places to access the projection settings of Grid+, as described below.
- Access from the toolbar button, as shown in Working with projection in Grid+.
- Access from the File menu, as shown in Working with projection in Grid+.
- Access from the Tools menu, as shown in Working with projection in Grid+.
When it is selected, the Projection Settings form will appear as shown in Working with projection in Grid+. As mentioned in the information box below, The user is not able to change the coordinate system from this form as Grid+ chooses the WGS84 geographic coordinate system as a default setting. It means that when we create any files from Grid+ and then export them to external files, their coordinates are in Latitude and Longitude. Working with projection in Grid+ shows coordinates of a spline file when opening with the Notepad editor as an example. The first line of the file provides information on the coordinate system.
As a default setting, Grid+1.2 always works with the Geographic Coordinate System (GCS). It means that its coordinates are longitude and latitude.
Figure 1 Access projection settings from a toolbar button.
Figure 2 Access projection settings from File menu.
Figure 3 Access projection settings from Tools menu.
Figure 4 Projection Settings form.
Figure 5 Open a generated file by Grid+ with the Notepad editor.
The projection settings cannot be changed. However, Grid+ allows the user to convert from the geographic coordinate system for each file layer in the Layer Control panel to the Universal Transverse Mercator (UTM). The user must define the correct UTM zone number for the latitude and longitude location. For example, we make a grid by using Grid+ for the Caloosahatchee River in Florida, USA. As we define, this river is located in the northern hemisphere UTM zone 17. We now want to convert the grid from the geographic coordinate system to the UTM zone.
To do this, select the grid layer from the Layer Control panel, then Right-mouse click (RMC), select Properties as shown in Working with projection in Grid+. After that Grid Settings form will appear, select Coordinate System tab, as shown in Working with projection in Grid+, and then click the Convert button, the form of Coordinate System will pop up as shown in Working with projection in Grid+. Now, we need to define the correct target coordinate system to which we want to convert. In this case, we select UTM zone 17 in the northern hemisphere and then click OK button. Next, click OK button in the form of Working with projection in Grid+ to close it. At this stage, coordinate system conversion is done.
Figure 6 Select the Properties option of a layer in Layer Control (e.g., Grid layer).
Figure 7 Grid Settings: Coordinate System tab.
Figure 8 Convert Coordinate System.
Now, we will export the grid to an external grid file. Select the grid layer from the Layer Control panel, then Right-mouse click (RMC), select Export/Export Grid as shown in Working with projection in Grid+. After that Export Grid form will appear, enter a file name and click Save button, as shown in Working with projection in Grid+.
Open that grid file with the Notepad editor, we can see that the file contains UTM zone number information (e.g., 17 means that UTM zone 17, in the northern hemisphere) and coordinates values are easting and northing in meter unit, as shown in Working with projection in Grid+. UTM zone number will be negative for the southern hemisphere, as shown in Working with projection in Grid+.
The question is, with a file that is converted from geographic coordinates to UTM zone by Grid+, do we need to define a coordinate system when opening it by Grid+? The answer is no because Grid+ will get projection information in header lines from the file so that it will be located in the correct place.
Figure 9 Export the Grid layer to an external file (1).
Figure 10 Export the Grid layer to an external file (2).
Figure 11 Exported grid in the northern hemisphere.
Figure 12 Exported grid in the southern hemisphere.
In another case, when we open a file generated by a third party, for example, a shoreline *.LDB (Delft3D LDB format), do we need to define a coordinate system? The answer is yes.
In this case, we consider the shoreline as an overlay file so that we will click the Import button from the Toolbar, then select Import Overlay as shown in Working with projection in Grid+. The Import Overlay Layer form will pop up, select the file and click Open button, as shown in Working with projection in Grid+. As a result, a new shoreline layer is added to the Layer Control panel, as shown in Working with projection in Grid+. However, it is not located in a place as we expected when we RMC on that layer and select Zoom to Layer option because the file does not contain the coordinate system information, so Grid+ does not know. So, how do we make the shoreline located in the right places in the online background map?
To do that, we need to define the correct projection (coordinate system) to the file by RMC on that layer and then select Properties option, Overlay Properties form will pop up, select the Coordinate System tab and click Define button as shown in Working with projection in Grid+. The Coordinate System the form will appear, as shown in Working with projection in Grid+, and we will select the correct projection from this form. The projection is supposed to be what we already know. In this case, we select UTM zone 17, northern hemisphere. After that, click OK button, this form will close and go back to the form in Working with projection in Grid+. Next, click OK button to close the form. At this stage, the process of defining the coordinate system is completed. RMC on the shoreline layer and select Zoom to Layer, it will be located in the correct place, as shown in Working with projection in Grid+.
Figure 13 Import third-party files with Grid+.
Figure 14 Select the file to import.
Figure 15 New shoreline layer added to Layer Control.
Figure 16 Coordinate System: Define.
Figure 17 Coordinate System: Define.
Figure 18 Shoreline located in the correct place after defining a coordinate system.