Sunday, February 5, 2012

[Matlab] Convert a 2D mesh to a single kml file

function mesh2kml(kmlfile,long,lat,iskip,jskip)
% convert a 2D mesh grid into a single plain kml file
%             will create the horizontal and vertical mesh-line seperately
% usage:
%             mesh2kml(kml-filename,longitude,latitude [iskip, jskip])
%                     iskip: reduce the points when to generate i-direction-mesh-line
%                     jskip: reduce the points when to generate j-direction-mesh-line
%     e.g.,
%             lon=-90:2:20;
%             lat=37:65;
%             [lon,lat]=meshgrid(lon,lat);
%             mesh2kml('mesh2kml_test',lon,lat,1,1);
%             will produce a kml file named mesh2kml_test in current folder
%
%             http://scriptdemo.blogspot.com

if nargin<3
   help mesh2kml
   return
end
if nargin==3
   iskip=5;
   jskip=5;
elseif nargin==4
   jskip=5;
end

fid=fopen([kmlfile,'.kml'],'wt');
writekmlHeader(fid,kmlfile);
if length(long)~=numel(long) % mesh
   [NY,NX]=size(long);
   %i-index
   longUD=flipud(long); latUD=flipud(lat);
   longI=long; latI=lat;
   longI(:,2:2:end)=longUD(:,2:2:end);
   latI(:,2:2:end)=latUD(:,2:2:end); clear longUD latUD
   jindex=sort(unique([1 jskip:jskip:NY NY]));
   longI=reshape(longI(jindex,:),1,[]); latI=reshape(latI(jindex,:),1,[]);
   fprintf(fid,'%s \n','<Placemark>');
   fprintf(fid,'%s \n',['<name>',kmlfile,'-I</name>']);
   fprintf(fid,'%s \n','<LineString>');
   fprintf(fid,'%s \n','<tessellate>1</tessellate>'); %
   fprintf(fid,'%s \n','<coordinates>');
   fprintf(fid,'%0.6f,%0.6f,0.0 \n', [longI;latI]);
   fprintf(fid,'%s \n','</coordinates>');
   fprintf(fid,'%s \n','</LineString>');
   fprintf(fid,'%s \n','</Placemark>');

   %j-index
   longLR=fliplr(long); latLR=fliplr(lat);
   longJ=long; latJ=lat;
   longJ(2:2:end,:)=longLR(2:2:end,:);
   latJ(2:2:end,:)=latLR(2:2:end,:); clear longLR latLR
   longJ=longJ'; latJ=latJ';
   iindex=sort(unique([1 iskip:iskip:NX NX]));
   longJ=reshape(longJ(iindex,:),1,[]); latJ=reshape(latJ(iindex,:),1,[]);

   fprintf(fid,'%s \n','<Placemark>');
   fprintf(fid,'%s \n',['<name>',kmlfile,'-J</name>']);
   fprintf(fid,'%s \n','<LineString>');
   fprintf(fid,'%s \n','<tessellate>1</tessellate>'); %
   fprintf(fid,'%s \n','<coordinates>');
   fprintf(fid,'%0.6f,%0.6f,0.0 \n', [longJ;latJ]);
   fprintf(fid,'%s \n','</coordinates>');
   fprintf(fid,'%s \n','</LineString>');
   fprintf(fid,'%s \n','</Placemark>');

else
   long=reshape(long,1,[]); lat=reshape(lat,1,[]);
   fprintf(fid,'%s \n','<Placemark>');
   fprintf(fid,'%s \n',['<name>',kmlfile,'</name>']);
   fprintf(fid,'%s \n','<LineString>');
   fprintf(fid,'%s \n','<tessellate>1</tessellate>'); %
   fprintf(fid,'%s \n','<coordinates>');
   fprintf(fid,'%0.6f,%0.6f,0.0 \n', [long;lat]);
   fprintf(fid,'%s \n','</coordinates>');
   fprintf(fid,'%s \n','</LineString>');
   fprintf(fid,'%s \n','</Placemark>');
end

writekmlEnd(fid);
fclose(fid);

function writekmlHeader(fid,kmlName)
fprintf(fid,'%s \n','<?xml version="1.0" encoding="UTF-8"?>');
fprintf(fid,'%s','<kml xmlns="http://www.opengis.net/kml/2.2" xmlns:gx="http://www.google.com/kml/ext/2.2" ');
fprintf(fid,'%s \n','xmlns:kml="http://www.opengis.net/kml/2.2" xmlns:atom="http://www.w3.org/2005/Atom">');
fprintf(fid,'%s \n','<Document>');
fprintf(fid,'%s \n',['<name>',kmlName,'.kml</name>']);


function writekmlEnd(fid)

fprintf(fid,'%s \n','</Document>');
fprintf(fid,'%s \n','</kml>');

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