MATLAB Examples

ramp documentation

The ramp function plots the Radarsat Antarctic Mapping Project version 2 using Antarctic Mapping Tools for Matlab. RAMP data are described in full on the NSIDC website. If you use RAMP data, please include the Liu citation listed at the bottom of this page.

Contents

Syntax

ramp
ramp('xy')
ramp('res',resolution)
[h,I,lat,lon] = ramp(...)

Description

ramp plots a RAMP image.

ramp('xy') specifies polar stereographic x,y coordinates in meters. If you do not have Matlab's Mapping Toolbox, the 'xy' option is selected automatically.

ramp('res',resolution) specifies a plotting resolution in meters. By default, resolution is set automatically based on the spatial extents of the current map.

[h,I,lat,lon] = ramp(...) returns a graphics handle h, RAMP image I, and geo coordinates lat and lon corresponding to each pixel in I.

Requirements

This function requires

  • Chad Greene's Antarctic Mapping Tools package for Matlab and
  • Matlab's Image Processing Toolbox.
  • A license for Matlab's Mapping Toolbox will extend some capabilities of the ramp function, but is not required.

The first time you run ramp, it will attempt to automatically download necessary RAMP data.

Example 1: Whole continent

To plot a whole continent's worth of RAMP data, just type ramp:

ramp
close % closes figure from Example 1

Example 2: Region

To plot a specific region, initialize a map first. For speed, the ramp function will only load RAMP data corresponding to the extents of a current map. Here we initialize an 800-km-wide map of Marie Byrd Land:

mapzoom('marie byrd land',800)
ramp
close % closes figure from Example 2

Example 3: Specify resolution

By default, the ramp function will load 200 meter resolution data. If extents of the current map are large, the ramp function will resize RAMP data (antialiasing employed) before plotting. Let's plot Beardmore Glacier at 500 m resolution:

mapzoom('beardmore glacier')
ramp('resolution',500);

Just for fun, let's use the measures function to overlay semitransparent ice speed. A grayscale colormap is already associated with the RAMP image in this figure, so I use the FEX function freezeColors to allow use of a second colormap. I haven't fully made the switch yet to the new graphics system which was introduced in Matlab R2014b, so I'm mimicking the new parula colormap with paruly.

freezeColors
measures('speed','beardmore glacier',...
    'colormap',paruly(256),'facealpha',.15)
scarlabel('Beardmore Glacier','fontangle','italic')
close % closes figure from Example 3

Example 4: Plotting in polar stereographic coordinates (No Mapping Toolbox)

If you have Matlab's Mapping Toolbox, ramp will plot in georeferenced coordinates by default. If you don't have the Mapping Toolbox, simple polar stereographic coordinates are chosen automatically. If you have the Mapping Toolbox, but want to plot in polar stereographic coordinates, simply include the 'xy' tag when you call ramp:

ramp('xy')
xlabel 'eastings (meters)'
ylabel 'northings (meters)'

Citing RAMP data

If you use RAMP data, please cite the following:

Liu, H., K. Jezek, B. Li, and Z. Zhao. 2001. Radarsat Antarctic Mapping Project Digital Elevation Model Version 2. Boulder, Colorado USA: National Snow and Ice Data Center. http://dx.doi.org/10.5067/PXKC81A7WAXD.

Author Info

This function was written by Chad A. Greene of the Institute for Geophysics at the University of Texas in Austin (UTIG), July 2015.