3.7 Create Geographic Grid
Level of expertise required for this Chapter: Beginner; general Map Maker training
The new Unique Parcel Numbering (UPN) system – and also other features – depends on the geographical grid of UTM with a grid distance of 1 km. The design of a grid (based on UTM 30) is therefore very useful. See also Chapter 7.8.1 on UPN and the importance of the UTM-grid on Local Plan follow-up.
A) Generate the grid:
Size (width, height) of the grid cells (square boxes) (1)
Number of rows and columns the grid should have (2,3)
Easting (x value), where the grid should start in the West (in UTM coordinates) (4)
Northing (y value), where the grid should start in the North (in UTM coordinates) (5)
2. In Map Maker:
Main menu > Utilities > Vector utilities > Generate > Square cells >
Generate square cells window: Edge of square: Width (= height) of the grid cell (1, see below, in this example: 1000 m) > Rows: Enter number of rows (2) > Columns: Enter number of columns (3) > Left x: Enter the western edge (4) > Top y: Enter the northern edge (5) > OK >
Select folder > Define new file name > Save.
In the example below, a grid cell layer has been created with a matrix of 10 x 10, each cell 1000 m wide and high, by default numbered with an A1-based code.
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B) Assign labels:
If you want a more meaningful label in each grid cell, for example, the geographical coordinates to be used for the UPN system, you can assign them automatically: Copy the grid cell layer to the live layer > right-mouse > Live layer actions > IDs and labels > Generate Display labels based on coordinate > OK >
Generate Display labels based on co-ordinate windows: Select the resolution of the coordinates, in a 1 km grid this would be the ‘Kilometer resolution’ > OK
You have now created the coordinates in the label: The first three digits are the x (Easting) value, the last three digits are the y (Northing) of each cell.
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In a similar way, you can create a grid for War Office projection (see Annex 8).
1. You first generate a grid as explained above, disregarding the projection you are in.
2. You then convert it, specifying it as ‘Ghana Grid’ projection, to UTM 30. Main menu > Utilities > Latitude and Longitude utilities > XY file to another projection > Vector > Choose source map projection window: Ghana Grid > OK > Select folder and file > Open > Choose target map projection window: UTM 30 > OK > Choose folder > Specify new file name > OK
See also Chapter 5.2.2 for conversion.
3. You can now display or process it in your standard LUPMIS configuration like any other layer.
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See references to grids (flight index maps of pilot communities) through Annex 9.