{"id":7416,"date":"2016-05-20T09:00:08","date_gmt":"2016-05-20T13:00:08","guid":{"rendered":"https:\/\/blogs.mathworks.com\/pick\/?p=7416"},"modified":"2016-05-20T08:00:52","modified_gmt":"2016-05-20T12:00:52","slug":"where-are-you-flying-over","status":"publish","type":"post","link":"https:\/\/blogs.mathworks.com\/pick\/2016\/05\/20\/where-are-you-flying-over\/","title":{"rendered":"Where are you flying over?"},"content":{"rendered":"\r\n

Jiro<\/a>'s pick this week is CityName<\/a> by Richard Moore<\/a>.<\/p>

When I used to travel to various places in the U.S. for work, I would wonder which cities I was flying over during the flight. On some planes, they have seat back monitors that show the flight path with names of cities the plane is flying over.<\/p>

With Richard's CityName, I can do the same. I simply call the function like this<\/p>

[city, country, dist] = CityName(lat, lon)\r\n<\/pre>
and it returns the closest city to the latitude and logitude location based on the GeoNames 5000 cities. It also returns the distance (in km) from the city center.<\/p>
Lets say that I am flying from Boston, Massachusetts to Los Angeles, California.<\/p>
boston = [42.36 -71.06];\r\nlos = [34.052 -118.244];\r\n<\/pre>
We can plot the map of the U.S. using the Mapping Toolbox<\/a>.<\/p>
ax = usamap('conus'<\/span>);\r\nstates = shaperead('usastatehi'<\/span>, 'UseGeoCoords'<\/span>, true,...<\/span>\r\n  'Selector'<\/span>, {@(name) ~any(strcmp(name,{'Alaska'<\/span>,'Hawaii'<\/span>})), 'Name'<\/span>});\r\ngeoshow(ax, states, 'DisplayType'<\/span>, 'polygon'<\/span>, 'FaceColor'<\/span>, [0.5 1 0.5])\r\nframem off<\/span>, gridm off<\/span>, mlabel off<\/span>, plabel off<\/span>\r\n<\/pre>
\"\" <\/p>
Next, we can calculate the great circle track between the two cities, again using track2<\/tt><\/a> from the Mapping Toolbox. Yes, this is not the path a plane would take, but for the purpose of this post, this will do.<\/p>
[lat,lon] = track2(boston(1),boston(2),los(1),los(2));\r\n<\/pre>
Now, we can write a loop for each coordinate to find the closest city within 10 km of the path.<\/p>
% Figure out view limits for animation purpose<\/span>\r\nsLim = [1386896     3288804     4332357     5404342];\r\neLim = [-2438739     -536831     3335946     4407931];\r\nlimits = [linspace(sLim(1),eLim(1))',linspace(sLim(2),eLim(2))',...<\/span>\r\n    linspace(sLim(3),eLim(3))',linspace(sLim(4),eLim(4))'];\r\n\r\nright = true;   % Used for text placement<\/span>\r\nfor<\/span> id = 1:100\r\n    % Plot a segment for the path<\/span>\r\n    if<\/span> id < 100\r\n        plotm(lat(id:id+1),lon(id:id+1),'Color'<\/span>,'r'<\/span>,'LineWidth'<\/span>,2)\r\n    end<\/span>\r\n\r\n    % Set axis limits<\/span>\r\n    axis(limits(id,:))\r\n\r\n    % Find closest city<\/span>\r\n    [c,~,dist] = CityName(lat(id),lon(id));\r\n\r\n    % If the distance is within 10 km, display name of the city<\/span>\r\n    if<\/span> dist < 10\r\n        c = strtrim(c);\r\n\r\n        % Place point<\/span>\r\n        plotm(lat(id),lon(id),'Color'<\/span>,'b'<\/span>,'Marker'<\/span>,'o'<\/span>,'MarkerFaceColor'<\/span>,'b'<\/span>)\r\n\r\n        % Display name of city. Alternate placing text on right and left.<\/span>\r\n        if<\/span> right\r\n            textm(lat(id),lon(id),c,...<\/span>\r\n                'HorizontalAlignment'<\/span>,'left'<\/span>,'VerticalAlignment'<\/span>,'top'<\/span>,...<\/span>\r\n                'FontSize'<\/span>,12,'FontWeight'<\/span>,'bold'<\/span>,'Color'<\/span>,'r'<\/span>)\r\n        else<\/span>\r\n            textm(lat(id),lon(id),c,...<\/span>\r\n                'HorizontalAlignment'<\/span>,'right'<\/span>,'VerticalAlignment'<\/span>,'bottom'<\/span>,...<\/span>\r\n                'FontSize'<\/span>,12,'FontWeight'<\/span>,'bold'<\/span>,'Color'<\/span>,'r'<\/span>)\r\n        end<\/span>\r\n        right = ~right;\r\n    end<\/span>\r\n    drawnow\r\nend<\/span>\r\n<\/pre>
\"\" <\/p>
Comments<\/b><\/p>
Give this a try and let us know what you think here<\/a> or leave a comment<\/a> for Richard.<\/p>