有沒有辦法通過google API獲取海拔剖面數(shù)據(jù)來檢查兩點(diǎn)之間是否有視線？例如，我可以通過此鏈接獲取海拔剖面圖：https ://maps.googleapis.com/maps/api/elevation/json?path=36.578581,-118.291994|36.23998,-116.83171&samples=10&key=YOUR_API_KEY結(jié)果是一個 json，其中 10 個點(diǎn)位于兩點(diǎn)之間，地面高程，例如： { "results" : [ { "elevation" : 4411.94189453125, "location" : { "lat" : 36.578581, "lng" : -118.291994 }, "resolution" : 19.08790397644043 }, { "elevation" : 1658.561645507812, "location" : { "lat" : 36.54183904164596, "lng" : -118.1291141726249 }, "resolution" : 9.543951988220215 }, { "elevation" : 1085.295776367188, "location" : { "lat" : 36.50487579522382, "lng" : -117.966389550823 }, "resolution" : 9.543951988220215 }, { "elevation" : 1491.4912109375, "location" : { "lat" : 36.46769177008888, "lng" : -117.8038207060907 }, "resolution" : 9.543951988220215 }, { "elevation" : 1583.762817382812, "location" : { "lat" : 36.43028747728768, "lng" : -117.6414082023003 }, "resolution" : 9.543951988220215 }, { "elevation" : 488.8834228515625, "location" : { "lat" : 36.39266342953181, "lng" : -117.4791525957044 }, "resolution" : 9.543951988220215 }, { "elevation" : 933.0382080078125, "location" : { "lat" : 36.35482014117158, "lng" : -117.3170544349424 }, "resolution" : 9.543951988220215 }, { "elevation" : 1657.123779296875, "location" : { "lat" : 36.31675812816988, "lng" : -117.1551142610472 }, "resolution" : 9.543951988220215 }, } ], "status" : "OK"}是否有數(shù)學(xué)公式來檢查是否可以看到 A 點(diǎn)和 B 點(diǎn)？我需要用 PHP 編寫代碼。
1 回答
慕勒3428872
TA貢獻(xiàn)1848條經(jīng)驗 獲得超6個贊
鑒于您正在沿著一條直線處理 2 個點(diǎn)，我認(rèn)為處理此問題的最簡單方法是從 2D 角度查看它，其中 x 軸表示您的樣本編號，y 軸表示你的高度。
然后我們假設(shè)如果結(jié)果 n 處的高程高于直線，則視線中斷。
在哪里：
(x1, y1) = (1, 4411.94)
(x2, y2) = (10, -84.51)
這是繪制出的結(jié)果的圖片以及在其上繪制的從一點(diǎn)到另一點(diǎn)的線：
我們可以看到樣本 8 和 9 的視線被打破了。
下面是查找相同內(nèi)容的代碼。它使用直線的基本方程：y = mx + c
$results_json = json_decode('{"results":[{"elevation":4411.94189453125,"location":{"lat":36.578581,"lng":-118.291994},"resolution":19.08790397644043},{"elevation":1658.561645507812,"location":{"lat":36.54183904164596,"lng":-118.1291141726249},"resolution":9.543951988220215},{"elevation":1085.295776367188,"location":{"lat":36.50487579522382,"lng":-117.966389550823},"resolution":9.543951988220215},{"elevation":1491.4912109375,"location":{"lat":36.46769177008888,"lng":-117.8038207060907},"resolution":9.543951988220215},{"elevation":1583.762817382812,"location":{"lat":36.43028747728768,"lng":-117.6414082023003},"resolution":9.543951988220215},{"elevation":488.8834228515625,"location":{"lat":36.39266342953181,"lng":-117.4791525957044},"resolution":9.543951988220215},{"elevation":933.0382080078125,"location":{"lat":36.35482014117158,"lng":-117.3170544349424},"resolution":9.543951988220215},{"elevation":1657.123779296875,"location":{"lat":36.31675812816988,"lng":-117.1551142610472},"resolution":9.543951988220215},{"elevation":1074.835205078125,"location":{"lat":36.27847790807609,"lng``":-116.9933326074523},"resolution":9.543951988220215},{"elevation":-84.51690673828125,"location":{"lat":36.23998,"lng":-116.83171},"resolution":9.543951988220215}],"status":"OK"}');
$x1 = 0;
$x2 = count($results_json->results);
$y1 = $results_json->results[0]->elevation;
$y2 = $results_json->results[$x2 - 1]->elevation; // last result in results array
$m = ($y2 - $y1) / ($x2 - $x1); // slope of the line
$c = $y2 - ($m * $x2);
$i = 0;
foreach ($results_json->results as $result){
$elevation_of_straight_line = ($m * $i) + $c;
$elevation_of_result = $result->elevation;
if ($elevation_of_result > $elevation_of_straight_line){
echo 'line of sight broken';
echo 'Elevation of sample index '.$i.' = '.$elevation_of_result;
echo 'Elevation of line of sight = '.$elevation_of_straight_line;
}
$i++;
}
這消除了從 3D 角度看這個問題所帶來的復(fù)雜性。盡管在地球曲率發(fā)揮作用的情況下，這有其缺點(diǎn)。這也應(yīng)該可以根據(jù)需要擴(kuò)展到盡可能多的樣本。
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