BigQuery Geo 函数 - 如何计算到多边形周长的最短距离

Question

我想使用内置的 BigQuery Geo 函数计算从下图中的黄色点到多边形边界的最短距离。

我自己找不到任何东西。

这是构建示例的查询。

WITH objects AS(
  SELECT 'POLYGON((-84.3043408314983 33.78004925, -84.3058929975152 33.7780287948446, -84.3026549053438 33.77962155, -84.3018234603607 33.7798783, -84.3041030408163 33.7785105714286, -84.2983655895464 33.7814847396304, -84.2869801170094 33.7772419185107, -84.2842584693878 33.7827876938775, -84.2863881748169 33.7848439284835, -84.2963746470588 33.7897689411765, -84.2979002513655 33.790508814658, -84.2978883265306 33.7851126734694, -84.300035153059 33.78268675, -84.3043408314983 33.78004925))' wkt_string
  UNION ALL
  SELECT 'POINT(-84.2998716702097 33.7796025711153)' wkt_string

)

SELECT ST_GEOGFROMTEXT(wkt_string) geo
FROM objects

Answer 1

这是我一直在寻找的功能：

ST_CLOSESTPOINT(geography_1, geography_2[ use_spheroid]).

Answer 2

使用ST_Distance函数计算形状之间的最短距离：

WITH objects AS(
  SELECT 
  'POLYGON((-84.3043408314983 33.78004925, -84.3058929975152 33.7780287948446, -84.3026549053438 33.77962155, -84.3018234603607 33.7798783, -84.3041030408163 33.7785105714286, -84.2983655895464 33.7814847396304, -84.2869801170094 33.7772419185107, -84.2842584693878 33.7827876938775, -84.2863881748169 33.7848439284835, -84.2963746470588 33.7897689411765, -84.2979002513655 33.790508814658, -84.2978883265306 33.7851126734694, -84.300035153059 33.78268675, -84.3043408314983 33.78004925))' 
   AS poly,
  'POINT(-84.2998716702097 33.7796025711153)' AS point
)
SELECT ST_Distance(ST_GEOGFROMTEXT(poly), ST_GEOGFROMTEXT(point))
FROM objects

一个警告 - 它计算点和多边形之间的距离，所以如果点在多边形内部，则距离为 0。如果你真的想要到多边形的距离边界，将ST_Boundary添加到组合中：

WITH objects AS(
   ...
)
SELECT ST_Distance(ST_Boundary(ST_GEOGFROMTEXT(poly)), ST_GEOGFROMTEXT(point))
FROM objects

BigQuery Geo 函数 - 如何计算到多边形周长的最短距离

BigQuery Geo functions - How to compute the shortest distance to the polygon perimeter

gis

google-bigquery