Types of Data Grids and Raster Display Functions

Mapping Toolbox™ functions and GUIs display both regular and geolocated data grids originating in a variety of formats. Recall that regular data grids require a referencing vector or matrix that describes the sampling and location of the data points, while geolocated data grids require matrices of latitude and longitude coordinates.

The data grid display functions are geographic analogies to the MATLAB® surface drawing functions, but operate specifically on map axes objects. Like the line-plotting functions discussed in the previous chapter, some Mapping Toolbox grid function names correspond to their MATLAB counterparts with an m appended.

    Note   Mapping Toolbox functions beginning with mesh are used for regular data grids, while those beginning with surf are reserved for geolocated data grids. This usage differs from the MATLAB definition; mesh plots are used for colored wire-frame views of the surface, while surf displays colored faceted surfaces.

Surface map objects can be displayed in a variety of different ways. You can assign colors from the figure colormap to surfaces according to the values of their data. You can also display images where the matrix data consists of indices into a colormap or display the matrix as a three-dimensional surface, with the z-coordinates given by the map matrix. You can use monochrome surfaces that reflect a pseudo-light source, thereby producing a three-dimensional, shaded relief model of the surface. Finally, you can use a combination of color and light shading to create a lighted shaded relief map.

The following table lists the available Mapping Toolbox surface map display functions.

Function

Used For

geoshow

Display map data gridded in latitude and longitude in 2-D

mapshow

Display gridded map data without projection in 2-D

meshm

Regular data grid warped to projected graticule mesh

surfm

Geolocated data grid projected on map axes

pcolorm

Projected data grid in z = 0 plane

surfacem

Data grid warped to projected graticule mesh

surflm

3-D shaded surface with lighting projected on map axes

meshlsrm

3-D lighted shaded relief of regular data grid

surflsrm

3-D lighted shaded relief of geolocated data grid

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