srElevation
The srElevation structure stores an elevation map in meters.

Elevation is defined relative to the reference ellipsoid.  Z-axis is positive upward; bathymetry is negative.  All required variables in srElevation.header are similar to those found in a GMT compatible .grd file (normal node registration).  srElevation.data is a 2-D grid (nx, ny) that is not rotated with respect to latitude and longitude.  srElevation.data(1,1) is located in the lower left hand corner.

Important Notes:

a) The elevation map must be larger in area than the spatial extent of the area to be image (srModel.u).  

b) The elevation map must not have empty or NaN values.

c)  A GMT .grd file can be converted to xyz using grd2xyz.  The output of grd2xyz is ordered by x then y, with the first node being in the upper left hand corner.  This is DIFFERENT from Stingray, which is also ordered by x then y, however, the first point is in the lower left hand corner.  An easy way to reformat the output of grd2xyz in Matlab is:

    srElevation.data = reshape(xyz(:,3),nx,ny);
  srElevation.data = fliplr(srElevation.data);
Example of Matlab display:  Geodetic
Example of Matlab display:  UTM
Required Fields
Derived Fields
 
Example of Matlab display:
Geodetic Coordinate System
srElevation =

       header: [-104.67 -103.83 8.1667 10.333 0.00136 0.0013609 614 1593]
         data: [614x1593 double]
     filename: ‘/Users/drt/Projects/Undershoot/Skew/srInput/srElevation_900.mat’
    longitude: [1x614 double]
     latitude: [1593x1 double]
          LAT: [614x1593 double]
          LON: [614x1593 double]
            X: [614x1593 double]
            Y: [614x1593 double]
UTM Coordinate System
srElevation

srElevation =

      header: [451.9 462.4 6516.6 6526.8 0.05 0.05 211 205]
        data: [211x205 double]
    filename: ‘/Users/drt/Projects/Luno/srInput/srElevation_Luno.mat’
     easting: [1x211 double]
    northing: [205x1 double]
     EASTING: [211x205 double]
    NORTHING: [211x205 double]
Required Fields:

Geographic Coordinate System is geodetic (srGeometry.tf_latlon=true)

srElevation.header
srElevation.header(1)
 decimal degrees
x_min
srElevation.header(2)
 decimal degrees
x_max
srElevation.header(3)
 decimal degrees
 y_min
srElevation.header(4)
 decimal degrees
y_max
srElevation.header(5)
decimal degrees
 x_inc
srElevation.header(6)
 decimal degrees
 y_inc
srElevation.header(7)
 integer
 nx
srElevation.header(8)
 integer
 ny
srElevation.data
 2-D array (nx,ny)
 meters

Geographic Coordinate System is geodetic UTM (srGeometry.tf_latlon=false)

srElevation.header
srElevation.header(1)
 kilometers
 x_min
srElevation.header(2)
 kilometers
 x_max
srElevation.header(3)
 kilometers
 y_min
srElevation.header(4)
 kilometers
y_max
srElevation.header(5)
kilometers
 x_inc
srElevation.header(6)
 kilometers
 y_inc
srElevation.header(7)
 integer
 nx
srElevation.header(8)
 integer
 ny
srElevation.data
 2-D array (nx,ny)
 meters


Derived Fields:

srElevation.longitude
decimal degrees
 Longitude of grid points (row vector)
srElevation.latitude
 decimal degrees
 Latitude of grid points (column vector)
srElevation.LON
 decimal degrees
 Longitude of grid points (mesh)
srElevation.LAT
 decimal degrees
 Latitude of grid points (mesh)


 
Plotting the srElevation Structure
Stingray/toolbox/plot_srElevation.m
plot1.tif
srElevation.longitude   = linspace(srElevation.header(1), ...
                        srElevation.header(1)+(srElevation.header(7)-1)*srElevation.header(5),...
                        srElevation.header(7));      % Row vector

srElevation.latitude    = linspace(srElevation.header(3), ...
                        srElevation.header(3)+(srElevation.header(8)-1)*srElevation.header(6),...
                        srElevation.header(8))’;     % Transpose to be a column vector