MATLAB: How to convert a raster geodata into vector geodata using the Mapping Toolbox

.shpconversioncountourgeodatageostructmappingMapping Toolboxrastershapetoolboxvector

I would like to have a way of converting raster geodata into a vector geodata and then plot it. My geodata represents terrain relief and I would like to extract contour lines from it.

Best Answer

The raster geodata can be converted into a vector geodata in the Mapping Toolbox as described in the example below:

1. Set up a map axes using WORLDMAP

2. Use CONTOURM to plot and return contours of that surface

3. Parse the contour matrix from CONTOURM into a version 2 latitude/longitude geostruct

4. Construct a symbolspec for the vectors and display the geostruct using GEOSHOW

You can download the attached file "extractContours.m" which implements the steps mentioned above.

Related Solutions

MATLAB: How can we find the non common strings from multiple columns

First lets find the strings that are common to all cell arrays:

listA={'India','Iran','Ireland','Israel','Jordan','Kuwait','Lebanon','Lesotho','Libya','Luxembourg','Malawi','Maldives','Morocco','Nepal','Netherlands','Norway','Oman','Paraguay','Peru','Philippines',};
listB={'Denmark','El Salvador','Gabon','Gambia','Lebanon','Lesotho','Libya','Luxembourg','Malawi','Maldives','Morocco','Nepal','Netherlands','Norway','Oman','Paraguay','Peru','Philippines','Qatar','Rwanda','Saudi Arabia','Senegal','Singapore','Sudan'};
listC={'Kuwait','Lebanon','Lesotho','Nepal','Netherlands','Oman','Sweden','Syria','Tanzania','Turkey','Uruguay'};
%

lists = {listA,listB,listC}; % storing data together makes working with them much simpler.
%
exc = lists{1};
for k = 2:numel(lists)
    exc = intersect(exc,lists{k});
end

giving the strings found in all cell arrays as:

 exc =
    'Lebanon'
    'Lesotho'
    'Nepal'
    'Netherlands'
    'Oman'

Now we can easily get the input cell arrays with the strings from exc removed:

out = cell(size(lists));
for k = 1:numel(lists)
    out{k} = setdiff(lists{k},exc);
end

giving:

>> out{:}
ans = 
    'India' 'Iran' 'Ireland' 'Israel' 'Jordan' 'Kuwait' 'Libya' 'Luxembourg' 'Malawi' 'Maldives' 'Morocco' 'Norway' 'Paraguay' 'Peru' 'Philippines'
ans =
    'Denmark' 'El Salvador' 'Gabon' 'Gambia' 'Libya' 'Luxembourg' 'Malawi' 'Maldives' 'Morocco' 'Norway' 'Paraguay' 'Peru' 'Philippines' 'Qatar' 'Rwanda' 'Saudi Arabia' 'Senegal' 'Singapore' 'Sudan'
ans =
    'Kuwait' 'Sweden' 'Syria' 'Tanzania' 'Turkey' 'Uruguay'

And if you want a list of all strings together, excluding those in exc:

uni = {};
for k = 1:numel(lists)
    uni = union(uni,lists{k});
end
uni = setdiff(uni,exc)

gives:

uni =
    'Denmark' 'El Salvador' 'Gabon' 'Gambia' 'India' 'Iran' 'Ireland' 'Israel' 'Jordan' 'Kuwait' 'Libya' 'Luxembourg' 'Malawi' 'Maldives' 'Morocco' 'Norway' 'Paraguay' 'Peru' 'Philippines' 'Qatar' 'Rwanda' 'Saudi Arabia' 'Senegal' 'Singapore' 'Sudan' 'Sweden' 'Syria' 'Tanzania' 'Turkey' 'Uruguay'

MATLAB: How to calculate the value in a raster geodata matrix given the referencing matrix and the geographic co-ordinates in Mapping Toolbox 2.7 (R2008a)

The example below illustrates how to calculate the altitude or value given a geographic location in raster geodata.

Assuming the raster geodata is stored in a matrix "topo" that stores altitudes in a world map:

[row, col] = latlon2pix(R,lat,lon);
Z = interp2(topo, col, row);

The code above first calculates the indices in the raster matrix corresponding to the provided (lat,lon) coordinates and then interpolates the data to estimate the altitude. The example attached below builds on the code above.

Best Answer

Related Solutions

MATLAB: How can we find the non common strings from multiple columns

MATLAB: How to calculate the value in a raster geodata matrix given the referencing matrix and the geographic co-ordinates in Mapping Toolbox 2.7 (R2008a)

Related Question