worldGrid

World coordinates of raster elements

Since R2021a

Syntax

[X,Y] = worldGrid(R)

[X,Y] = worldGrid(R,gridOption)

Description

[X,Y] = worldGrid(R) returns the world coordinates of raster elements as the 2-D arrays X and Y. The coordinates of raster element (i,j) are (X(i,j),Y(i,j)).

[X,Y] = worldGrid(R,gridOption), where gridOption is "gridvectors", returns X and Y as row vectors. The coordinates of raster element (i,j) are (X(j),Y(i)). The default for gridOption is "fullgrid", which returns X and Y as 2-D arrays.

Examples

Find Coordinates of Raster Elements

Import elevation data, find the coordinates of the imported data, then display the data as a surface.

First import elevation data [1] for an area around Mount Washington as an array and a map cells reference object. Prepare the data for plotting by specifying the output type as "double".

[Z,R] = readgeoraster("MtWashington-ft.grd",OutputType="double");

Find the coordinates of each element in the array.

[X,Y] = worldGrid(R);

Display the elevation data as a surface using an appropriate colormap. Set the EdgeColor property to "none" to remove the mesh from the surface.

surf(X,Y,Z,EdgeColor="none")
demcmap(Z)
xlabel("x (meters)")
ylabel("y (meters)")
zlabel("Elevation (feet)")

[1] The elevation data used in this example is courtesy of the U.S. Geological Survey.

Get Vectors Instead of Arrays

Create a map cells reference object for a 3-by-4 raster with x values in the range [7000, 7400] meters and y values in the range [2700, 3300] meters. Get the coordinates of the raster elements and return them as row vectors.

R = maprefcells([7000 7400],[2700 3300],[3 4]);
[X,Y] = worldGrid(R,'gridvectors')

X = 1×4

        7050        7150        7250        7350

Y = 1×3

        2800        3000        3200

If you do not specify the second argument as 'gridvectors', then the worldGrid function returns 2-D arrays by default.

[xFull,yFull] = worldGrid(R)

xFull = 3×4

        7050        7150        7250        7350
        7050        7150        7250        7350
        7050        7150        7250        7350

yFull = 3×4

        2800        2800        2800        2800
        3000        3000        3000        3000
        3200        3200        3200        3200

Input Arguments

R — Spatial reference

MapCellsReference object | MapPostingsReference object

Spatial reference, specified as a MapCellsReference or MapPostingsReference object.

If R is a MapCellsReference object, then X and Y are cell centers. If R is a MapPostingsReference object, then X and Y are posting points.

gridOption — Grid option

"fullgrid" (default) | "gridvectors"

Grid option, specified as one of these values:

• "fullgrid" — Return X and Y as 2-D arrays, where each row of X is identical and each column of Y is identical. This is the default behavior.

• "gridvectors" — Return X and Y as row vectors. Use this option when you want to reduce memory usage and when 2-D arrays are unnecessary, such as when plotting large data sets with the surf function. You can specify gridOption as "gridvectors" only when the TransformationType property of R has a value of "rectilinear".

This table shows the difference between "fullgrid" and "gridvectors".

"fullgrid"	"gridvectors"
R = maprefcells([7000 7400],[2700 3300],[3 4]); [X,Y] = worldGrid(R) X = 7050 7150 7250 7350 7050 7150 7250 7350 7050 7150 7250 7350 Y = 2800 2800 2800 2800 3000 3000 3000 3000 3200 3200 3200 3200	R = maprefcells([7000 7400],[2700 3300],[3 4]); [X,Y] = worldGrid(R,"gridvectors") X = 7050 7150 7250 7350 Y = 2800 3000 3200

Data Types: char | string

Output Arguments

X — x-coordinates

2-D array (default) | row vector

x-coordinates, returned as a 2-D array or a row vector. By default, X is a 2-D array. To return X as a row vector, specify gridOption as "gridvectors".

By default, and when gridOption is "fullgrid", the sizes of X and Y each equal the RasterSize property of R. When gridOption is "gridvectors", the lengths of X and Y equal the second and first elements of the RasterSize property of R, respectively.

Y — y-coordinates

2-D array (default) | row vector

y-coordinates, returned as a 2-D array or a row vector. By default, Y is a 2-D array. To return Y as a row vector, specify gridOption as "gridvectors".

By default, and when gridOption is "fullgrid", the sizes of X and Y each equal the RasterSize property of R. When gridOption is "gridvectors", the lengths of X and Y equal the second and first elements of the RasterSize property of R, respectively.

Version History

Introduced in R2021a