Grid+1.2 allows loading an existing grid built under several formats, the most EE-compatible of which are *.gpc, *.cvl and *.grd. To import a grid, navigate towards the Import Grid buttons that are accessible in File > Import (Figure 1) or the Toolbars (Figure 2). Browse to the file location after Import Grid and select to open the grid.
Figure 1 Import Grid option via the Menu bar
Figure 2 Import Grid option via the Toolbar
A grid file may or may not contain its projection information. In the former case, Grid+1.2 automatically reads the abided coordinate system and overlays the grid accurately on its geographical location in the background map, for example as in Figure 3. In the latter case, the grid display is prone to distortion, immediately noticeable in the working domain (Figure 4).
Figure 3 The grid of Caspian Sea correctly located by Grid+1.2 after being imported. The red box in the left displays automatically-identified coordinate system of the grid.
Figure 4 Distorted Caspian Sea grid with unspecified coordinate projection information. Grid file formatted as *.grd.
To fix the distortion issue, the user needs to define the projection of the grid. To do this, right-mouse click on the grid layer in the Layer Control and then select Properties. The Grid Settings form will pop up (Figure 5). Move to the Coordinate System tab, click the Define button. Then, the user should select the proper spatial reference, either geographic or UTM coordinate system. In the Caspian Sea case study, for example, the correct coordinate system is UTM, Northern Hemisphere, UTM Zone 39 (Figure 6). Click the OK button to finish projection-defining. Next, right-mouse click on the grid layer in the Layer Control, then select Zoom to Layer option, the grid will be located in the right place (Figure 7).
Figure 5 Grid Setting form
Figure 6 Define a coordinate system
Figure 7 Grid displayed correctly after the coordinate system is set