To make a georeferenced map or access general settings for Grid+, go to the Tools menu as shown in Figure Tools Menu#Tools Menu#Figure 1. The function of each option is described in the table below.
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Figure 1. Tools menu options.
| Options | Description |
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| Image Georeferencing | This option allows the user to make a background georeferenced map (described in detail below). |
| Coordinate Conversion | The option allows converting from a coordinate system to another coordinate system for a point. (described in detail below). |
| Unit Conversion | The option allows converting length, area, volume, etc from a unit to another unit. (described in detail below). |
| Settings | General settings for Grid+ |
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Define the region of interest in Google Earth with two points (P1 and P2), as shown in Figure Tools Menu#Tools Menu#Figure 2. We will save the image to a file (with *.jpg extension format).
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By default, the coordinates of the four corner points of the image are updated in the Control Points frame, as shown in Figure Tools Menu#Tools Menu#Figure 3. LMC on the row numbering from the table to select a point of the Control Points, then we can find that point by clicking the Find Point button, or remove that point by clicking the Delete Point button. Clicking the Clear Point button will delete all points in the table. Click Add Point button then LMC on a point in the image to add a new point to the table (a new row is added).
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Figure 2. Make an image file with at least two points from Google Earth.
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Figure 3. Add an image to the Image georeference tool.
Now we will assign World X and World Y coordinates to defined points. Click the Clear Points to empty the Control Points frame and then usie the vertical and horizontal bars as shown in Figure Tools Menu#Tools Menu#Figure 4 to move the image to find the defined points (P1 and P2).
- Assigning coordinates for P1: After finding the P1 on the image, LMC on that point, its Image X and Image Y are updated in the Control Points frame. Now enter the coordinates for World X and World Y (UTM coordinates) then press the Enter key, and it will jump to the second row.
- Assigning coordinates for P2: Finding the P2 on the image, then LMC on that point, its Image X and Image Y are updated in the Control Points frame. Now enter the coordinates for World X and World Y (UTM coordinates). The UTM coordinates of the P1 and P2 have been defined previously, as shown in Figure Tools Menu#Tools Menu#Figure 2.
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Figure 4. Define and update coordinates for the control points.
Next, click the Save button, the Save As form will be displayed. Enter a file name. Select extension *.geo for file type then click the Save button (Figure Tools Menu#Tools Menu#Figure 5).
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Figure 5. Save the georeferenced file.
The georeferenced map can be made from multiple images by using the Add Images button and then assigning coordinates as described above. In case we want to remove the image from the Image Files frame, select that image then RMC to display the options. Select Remove Selected Image as shown in Figure Tools Menu#Tools Menu#Figure 6. Selecting Remove All Images will delete all images in the Image Files frame.
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Figure 6. RMC options in the Image Files frame.
Coordinate Conversion
The option allows converting from a coordinate system to another coordinate system for a point. The user should select the input projection and unit for the Convert from Coordinate System frame first then enter the values in the text box. Next, select the target projection and unit for the Convert to Coordinate System frame then click the Convert button to take place as shown in Tools Menu#Tools Menu#Figure 7. The UTM Zone in the Convert to Coordinate System frame must be defined when converting from Longitude, Latitude to UTM zone in meter or foot.
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Figure 7. Coordinate Conversion.
Unit Conversion
Select the unit conversion, the Unit Conversion form displays as Tools Menu#Tools Menu#Figure 8. It allows converting length, area, volume, etc from a unit to another unit. Firstly the user selects a unit from the drop-down list for Convert (e.g Length), next select from the drop-down list for the From Unit (meter(m)), then enter the value want to convert in the Input Value, next select the target unit for the To Unit (e.g foot (ft)), we can set the number of significant digits by entering a number (e.g 3). Finally, click the Convert button, the output value will be shown in the Output Value.
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Figure 8. Unit Conversion.
Settings
Selecting the Settings from the Tools menu will show the Global Settings form as shown in Figure 7 Tools Menu#Tools Menu#Figure 9. The values in this form are the default settings.
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Figure 7 9. Grid+ general settings.