补丁在地图上的洞

Question

我想达到以下结果：

正如您所看到的，我想修补整个地图，不包括源自位置A和位置B的small circles联合所形成的区域。

位置A和B具有以下坐标（以度为单位）：

% Coordinates.
A = [43.6350000000000, 1.36777777777778];
B = [52.7019444444445, -8.92472222222222];

我使用scircle1函数获取小圆圈的坐标。两个小圆的半径都是654海里：

% Small circles from center, range, and azimuth.
RangeNM = 654;
[latcA, loncA] = scircle1(A(1), A(2), RangeNM, [], earthRadius('nm'));
[latcB, loncB] = scircle1(B(1), B(2), RangeNM, [], earthRadius('nm'));

补丁的内部轮廓是由两个小圆圈的union的坐标形成的周长。我使用polybool函数获取坐标：

% Set operations on polygonal regions.
[latU, lonU] = polybool('union', latcA, loncA, latcB, loncB);

补丁的外部轮廓是由地图的纬度和经度限制形成的周界。我使用getm获取地图的MapLatLimit和MapLonLimit属性。从上图可以看出，LatLim = [30, 70]（30°N到70°N）和LonLim = [-30, 20]（30°W到20°E）：

% Get Map Latitude and Longitude limit.
LatLim = getm(gca, 'MapLatLimit');
LonLim = getm(gca, 'MapLonLimit');

最后，我尝试使用patchm函数创建补丁，这相当于映射的补丁函数。这是我遇到问题的地方。我尝试了三种不同的方法，但没有一种是成功的：

% APPROACH 1
lat = {[LatLim(1) LatLim(2) LatLim(2) LatLim(1) LatLim(1)], latU};
lon = {[LonLim(1) LonLim(1) LonLim(2) LonLim(2) LonLim(1)], lonU};
% Compute face and vertex matrices.
[f, v] = poly2fv(lat, lon);
patchm('Faces', f, 'Vertices', v, 'FaceColor', [.5 .5 .5], 'FaceAlpha', 0.4); %Doesn't work

% APPROACH 2
lat = {[LatLim(1) LatLim(2) LatLim(2) LatLim(1) LatLim(1)], latU};
lon = {[LonLim(1) LonLim(1) LonLim(2) LonLim(2) LonLim(1)], lonU};
% Compute face and vertex matrices.
[f, v] = poly2fv(lat, lon);
patchm(v(:,1), v(:,2), 'FaceColor', [.5 .5 .5], 'FaceAlpha', 0.4); % Doesn't work

% APPROACH 3
lat = [latU', LatLim(1), LatLim(2), LatLim(2), LatLim(1), LatLim(1)];
lon = [lonU', LonLim(1), LonLim(1), LonLim(2), LonLim(2), LonLim(1)];
patchm(lat, lon, 'FaceColor', [.5 .5 .5], 'FaceAlpha', 0.4); % Doesn't work

我非常感谢你的帮助。

我在poly2fv函数的文档页面中找到了一个非常好的带孔的补丁示例。但是，该示例使用标准patch函数和笛卡尔坐标（x，y）。请注意，使用了patch('Faces', f, 'Vertices', v,...。我试图使用patchm函数和地理坐标（lat，lon）复制同一个例子。

代码：

  

注意：此代码需要Mapping Toolbox。

% Read vector features and attributes from shapefile.
landareas = shaperead('landareas.shp', 'UseGeoCoords', true);

% Define map axes and set map properties.
axesm ('lambert',...
    'MapLonLimit', [-30 20],...
    'MapLatLimit', [30 70],...
    'MapParallels', [38.00555556 71.01111111],...
    'Frame', 'on',...
    'FLineWidth', 1,...
    'Grid', 'on',...
    'GLineStyle', '-',...
    'GLineWidth', 0.1,...
    'GColor', [.7 .7 .7]);

% Display map latitude and longitude data.
geoshow(landareas, 'FaceColor', [1 1 .5], 'EdgeColor', [.3 .3 .3]);

% Toggle and control display of graticule lines.
gridm('MLineLocation', 5,...
    'MLabelLocation', 5,...
    'PLineLocation', 5,...
    'PLabelLocation', 5);

% Toggle and control display of meridian labels.
mlabel on;

% Toggle and control display of parallel labels.
plabel on;

axis off;

% Coordinates.
A = [43.6350000000000, 1.36777777777778];
B = [52.7019444444445, -8.92472222222222];

% Plot A.
plotm(A(1), A(2), '.r');
textm(A(1), A(2)+1, 'A');

% Plot B.
plotm(B(1), B(2), '.r');
textm(B(1), B(2)+1, 'B');

% Small circles from center, range, and azimuth.
RangeNM = 654;
[latcA, loncA] = scircle1(A(1), A(2), RangeNM, [], earthRadius('nm'));
[latcB, loncB] = scircle1(B(1), B(2), RangeNM, [], earthRadius('nm'));

% Set operations on polygonal regions.
[latU, lonU] = polybool('union', latcA, loncA, latcB, loncB);

% Get Map Latitude and Longitude limit.
LatLim = getm(gca, 'MapLatLimit');
LonLim = getm(gca, 'MapLonLimit');

% APPROACH 1
lat = {[LatLim(1) LatLim(2) LatLim(2) LatLim(1) LatLim(1)], latU};
lon = {[LonLim(1) LonLim(1) LonLim(2) LonLim(2) LonLim(1)], lonU};
% Compute face and vertex matrices.
[f, v] = poly2fv(lat, lon);
patchm('Faces', f, 'Vertices', v, 'FaceColor', [.5 .5 .5], 'FaceAlpha', 0.4); % Doesn't work

% APPROACH 2
lat = {[LatLim(1) LatLim(2) LatLim(2) LatLim(1) LatLim(1)], latU};
lon = {[LonLim(1) LonLim(1) LonLim(2) LonLim(2) LonLim(1)], lonU};
% Compute face and vertex matrices.
[f, v] = poly2fv(lat, lon);
patchm(v(:,1), v(:,2), 'FaceColor', [.5 .5 .5], 'FaceAlpha', 0.4); % Doesn't work

% APPROACH 3
lat = [latU', LatLim(1), LatLim(2), LatLim(2), LatLim(1), LatLim(1)];
lon = [lonU', LonLim(1), LonLim(1), LonLim(2), LonLim(2), LonLim(1)];
patchm(lat, lon, 'FaceColor', [.5 .5 .5], 'FaceAlpha', 0.4); % Doesn't work

Answer 1

似乎patchm忽略了漏洞。解决方法是将周围的多边形分成两部分，以便区域的并集与两者重叠。然后从北部和南部补丁中减去该区域，绘制两个部分，并添加一个很好的边缘：

% Find a point where we can split the polygon
split_lat = median(latU);
% generate northern patch
p_up_lt = [split_lat LatLim([2 2]) split_lat];
p_up_lg = LonLim([1 1 2 2]);

[lonAup, latAup] = polybool('-', p_up_lg, p_up_lt, lonU, latU);
% and plot it, with invisible edge
p_up = patchm(latAup, lonAup, 'FaceColor', [.5 .5 .5], 'FaceAlpha', 0.4, 'EdgeColor', 'none');

% generate and plot southern patch
p_dn_lt =  [LatLim(1) split_lat split_lat LatLim(1)];
p_dn_lg =  LonLim([1 1 2 2]);
[lonAdn, latAdn] = polybool('-', p_dn_lg, p_dn_lt, lonU, latU);
p_dn = patchm(latAdn, lonAdn, 'FaceColor', [.5 .5 .5], 'FaceAlpha', 0.4, 'EdgeColor', 'none');

% plot edge for the union
p_e = patchm(latU, lonU, 'FaceColor', 'none', 'FaceAlpha', 0.4);