3.7 Create geographic grid - LUPMISManual

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3. GIS operations

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:

1. Calculate:

  • 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.


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