MATLAB: How to get Lat/Lon from vec2mtx

gridmapping

I am trying to generate grid lat/lon for a given polygon. First I tried to get the grids on the boundary first using vec2mtx. Then I generate grid inside polygon. My questions are 1. How to get the right Lat/Lon from the vec2mtx 2. What would be most efficient way to generate grid inside polygons 3. These grid data are just the points, not polygon. Is there any Matlab function I can convert them into polygon object.
      oriLat=[48.3860120000000;49.3686790000000;48.0145280000000;46.6825390000000;47.4787370000000;46.5073030000000;46.5176190000000;44.9243550000000;45.2906840000000;42.3015220000000;41.9182910000000;44.6990460000000;45.7893010000000;45.2741950000000;43.7351650000000;43.8312240000000;41.7326470000000;41.3863160000000;44.9774490000000;45.2345130000000;47.3537330000000;44.8174190000000;43.3218860000000;41.5511100000000;39.4791860000000;37.8949860000000;37.1004480000000;39.4531150000000;38.0365030000000;38.6352170000000;35.2258250000000;31.1253830000000;26.7715300000000;24.8661310000000;29.9185130000000;30.6849560000000;30.0184100000000;28.9338120000000;29.4307800000000;27.9083070000000;25.8403780000000;29.7380790000000;28.9821380000000;31.7520090000000;31.3322390000000;34.5540170000000;40.2609740000000;46.2591090000000;48.3860120000000];
      oriLon=[-124.725839000000;-94.9521110000000;-89.4892260000000;-91.9618890000000;-87.9292690000000;-87.3667670000000;-84.1179250000000;-87.8434330000000;-86.9777800000000;-87.8347690000000;-86.5978990000000;-86.2484740000000;-84.7727650000000;-83.3851040000000;-83.9477400000000;-82.6336410000000;-83.4538320000000;-82.4605990000000;-74.9927560000000;-70.8444300000000;-68.2697100000000;-66.9498950000000;-70.5538540000000;-69.9649820000000;-75.5930680000000;-75.3386230000000;-75.9796080000000;-76.0123120000000;-76.3220930000000;-77.2467040000000;-75.5336270000000;-81.4020960000000;-80.0321200000000;-80.6511890000000;-83.6792190000000;-88.0083960000000;-89.8450650000000;-89.4009660000000;-94.6703890000000;-97.0033250000000;-97.4226360000000;-101.400636000000;-103.281190000000;-106.417940000000;-111.074825000000;-120.622575000000;-124.363414000000;-123.547659000000;-124.725839000000];
      % plot( oriLon, oriLat, '-ob')
      gridDensity = 10; 
      [inGrid, inRefVec] = vec2mtx( oriLat, oriLon, gridDensity);
      % Trying to get grid Lat/Lon
      [latlim, lonlim] = limitm(inGrid, inRefVec);
      gridLon = [lonlim(1):1/gridDensity:lonlim(2)];
      gridLat = [latlim(1):1/gridDensity:latlim(2)];
      bndryLon = gridLon(1:end-1)+1/(gridDensity*2);
      bndryLat = gridLat(1:end-1)+1/(gridDensity*2);
      [Xbndry,Ybndry]= meshgrid( bndryLon, bndryLat);
      tloc= inGrid>0;
      % boundary grid
      bndryGrid= struct;
      bndryGrid.Lon = Xbndry(tloc); % only on the boundary
      bndryGrid.Lat = Ybndry(tloc);
      % making inner grid
      [Xgrid,Ygrid]= meshgrid( gridLon+1/(gridDensity*2), gridLat+1/(gridDensity*2));
      tloc= inpolygon( Xgrid, Ygrid, oriLon, oriLat); % This takes a really long time for large/dense gird or complex original polygon
      innerGrid= struct;
      innerGrid.Lon= Xgrid( tloc);
      innerGrid.Lat= Ygrid( tloc);
      figure; hold on
      plot( oriLon, oriLat, '-k')
      plot(  bndryGrid.Lon,  bndryGrid.Lat,'ob')
      plot( innerGrid.Lon, innerGrid.Lat, '.r')
% After combining the bndryGrid and innerGrid, how to convert them into polygon?

Best Answer

You have two options:
1. You can generate points inside in a scattered way...i.e generate a unstructured mesh, and you will get points inside that boundary specified. To do this, you can use Mesh2D package. https://in.mathworks.com/matlabcentral/fileexchange/25555-mesh2d-delaunay-based-unstructured-mesh-generation.
Hey, don't forget to comment and rate if you like this option at the link.
2. Generate points in a structured way. For this option check the below code.
oriLat=[48.3860120000000;49.3686790000000;48.0145280000000;46.6825390000000;47.4787370000000;46.5073030000000;46.5176190000000;44.9243550000000;45.2906840000000;42.3015220000000;41.9182910000000;44.6990460000000;45.7893010000000;45.2741950000000;43.7351650000000;43.8312240000000;41.7326470000000;41.3863160000000;44.9774490000000;45.2345130000000;47.3537330000000;44.8174190000000;43.3218860000000;41.5511100000000;39.4791860000000;37.8949860000000;37.1004480000000;39.4531150000000;38.0365030000000;38.6352170000000;35.2258250000000;31.1253830000000;26.7715300000000;24.8661310000000;29.9185130000000;30.6849560000000;30.0184100000000;28.9338120000000;29.4307800000000;27.9083070000000;25.8403780000000;29.7380790000000;28.9821380000000;31.7520090000000;31.3322390000000;34.5540170000000;40.2609740000000;46.2591090000000;48.3860120000000];
oriLon=[-124.725839000000;-94.9521110000000;-89.4892260000000;-91.9618890000000;-87.9292690000000;-87.3667670000000;-84.1179250000000;-87.8434330000000;-86.9777800000000;-87.8347690000000;-86.5978990000000;-86.2484740000000;-84.7727650000000;-83.3851040000000;-83.9477400000000;-82.6336410000000;-83.4538320000000;-82.4605990000000;-74.9927560000000;-70.8444300000000;-68.2697100000000;-66.9498950000000;-70.5538540000000;-69.9649820000000;-75.5930680000000;-75.3386230000000;-75.9796080000000;-76.0123120000000;-76.3220930000000;-77.2467040000000;-75.5336270000000;-81.4020960000000;-80.0321200000000;-80.6511890000000;-83.6792190000000;-88.0083960000000;-89.8450650000000;-89.4009660000000;-94.6703890000000;-97.0033250000000;-97.4226360000000;-101.400636000000;-103.281190000000;-106.417940000000;-111.074825000000;-120.622575000000;-124.363414000000;-123.547659000000;-124.725839000000];
N = 100 ;   % can be varied
lon = linspace(min(oriLon),max(oriLon),N) ;
lat = linspace(min(oriLat),max(oriLat),N) ;
%
[Lon,Lat] = meshgrid(lon,lat) ;
% pick points lying inside the given region 
idx = inpolygon(Lon(:), Lat(:),oriLon, oriLat) ;
Lon(~idx) = NaN ; Lat(~idx) = NaN ;
plot( oriLon, oriLat, 'b')
hold on
plot(Lon,Lat,'.r')
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