我有一个geography 多边形列。此列已被ST_Subdivided 用于多边形内点查找性能。
当我在距离 geography 类型的多边形边缘 < 10m 的点之间执行 ST_Intersects 时，我得到 false。但是在转换为geometry类型之后，我得到true:
SELECT
ST_Intersects(ST_GeogFromText('POINT(-118.46131 34.31171)'), latlong_shape) AS intersects_geog,
ST_Intersects(ST_GeogFromText('POINT(-118.46131 34.31171)')::geometry, latlong_shape::geometry) AS intersects_geom
FROM region_ids_for_latlong_shapes
WHERE ST_Distance(ST_GeogFromText('POINT(-118.46131 34.31171)'), latlong_shape) < 10;
| intersects_geog | intersects_geom |
| --------------- | --------------- |
| false | true |
| false | false |
我知道 ST_Intersects(geography, geography) 和 ST_Intersects(geometry, Geometry) 之间存在预期差异，但我不明白为什么它们会在这种情况下会发生:
- 几何形状有效
- 即使存在一些很大的圆差异，我也希望该点与其中一个多边形相交，而不是在两个多边形之外。
确定该点与哪个多边形相交的最准确方法是什么？我知道我可以转换为几何类型，但我'令我惊讶的是，ST_Intersect 的geography 支持在这里不起作用。是否可以在不进行强制转换的情况下准确地完成此操作？
这是该点和两个最接近的形状:
更多诊断:
SELECT
ST_Intersects(ST_GeogFromText('POINT(-118.46131 34.31171)'), latlong_shape) AS geogs_intersect,
ST_Intersects(ST_GeogFromText('POINT(-118.46131 34.31171)')::geometry, latlong_shape::geometry) AS geoms_intersect,
ST_IsValid(latlong_shape::geometry) AS geom_isvalid,
ST_Relate(ST_GeogFromText('POINT(-118.46131 34.31171)')::geometry, latlong_shape::geometry) AS relate_geoms,
ST_Distance(ST_GeogFromText('POINT(-118.46131 34.31171)'), latlong_shape) AS geogs_distance,
ST_Distance(ST_GeogFromText('POINT(-118.46131 34.31171)'), latlong_shape, false) AS geogs_no_spheroid_distance,
ST_Distance(ST_GeogFromText('POINT(-118.46131 34.31171)')::geometry, latlong_shape::geometry) AS geoms_distance,
ST_3DDistance(ST_GeogFromText('POINT(-118.46131 34.31171)')::geometry, latlong_shape::geometry) AS geoms_3d_distance
FROM region_ids_for_latlong_shapes
WHERE ST_Distance(ST_GeogFromText('POINT(-118.46131 34.31171)'), latlong_shape) < 10
| geogs_intersect | geoms_intersect | geom_isvalid | relate_geoms | geogs_distance | geogs_no_spheroid_distance | geoms_distance | geoms_3d_distance |
| --------------- | --------------- | ------------ | ------------ | -------------- | -------------------------- | ----------------------- | ----------------------- |
| false | true | true | 0FFFFF212 | 3.4064663 | 3.4146671 | 0 | 0 |
| false | false | true | FF0FFF212 | 5.63478588 | 5.64835122 | 0.000054321999996886916 | 0.000054321999996886916 |
SELECT VERSION()
| version |
| ----------------------------------------------------------------------------------------------------------------- |
| PostgreSQL 13.9 on x86_64-apple-darwin19.6.0, compiled by Apple clang version 11.0.3 (clang-1103.0.32.62), 64-bit |
SELECT PostGIS_Version();
| postgis_version |
| ------------------------------------- |
| 3.1 USE_GEOS=1 USE_PROJ=1 USE_STATS=1 |
为了方便起见，这是我在上面可视化的 GeoJSON。它包含查找点和两个最近的多边形(由 ST_AsGeoJSON 返回):
{
"type": "FeatureCollection",
"features": [
{
"type": "Feature",
"properties": {},
"geometry": {
"type": "Point",
"coordinates": [
-118.46131,
34.31171
]
}
},
{
"type": "Feature",
"properties": {},
"geometry": {
"type": "Polygon",
"coordinates": [
[
[
-118.590173754,
34.818203384
],
[
-118.554669477,
34.818248424
],
[
-118.519233938,
34.81833323
],
[
-118.500917157,
34.818263939
],
[
-118.484492998,
34.818255519
],
[
-118.466714818,
34.818356235
],
[
-118.431575103,
34.818707983
],
[
-118.413900556,
34.818924424
],
[
-118.396521556,
34.819207589
],
[
-118.375913258,
34.819322959
],
[
-118.326206757,
34.819675701
],
[
-118.298911338,
34.819887117
],
[
-118.298911338,
34.747356668
],
[
-118.30726467,
34.747324674
],
[
-118.311221449,
34.747259523
],
[
-118.315177432,
34.747194256
],
[
-118.316156934,
34.747178062
],
[
-118.31616929,
34.747315306
],
[
-118.316271488,
34.752065567
],
[
-118.312325229,
34.752140489
],
[
-118.312326535,
34.75219544
],
[
-118.312531114,
34.760874375
],
[
-118.311419271,
34.760887938
],
[
-118.311447254,
34.761794819
],
[
-118.307547133,
34.761876226
],
[
-118.307688072,
34.76914709
],
[
-118.312139537,
34.769051848
],
[
-118.312013231,
34.761782985
],
[
-118.320871559,
34.761596736
],
[
-118.320643006,
34.751982309
],
[
-118.32518382,
34.751892427
],
[
-118.325146684,
34.750645594
],
[
-118.320698938,
34.750725582
],
[
-118.320619613,
34.747238796
],
[
-118.320621472,
34.74711144
],
[
-118.319132498,
34.74712522
],
[
-118.31912928,
34.746989586
],
[
-118.318963759,
34.742294886
],
[
-118.324094459,
34.742214348
],
[
-118.324100254,
34.742351721
],
[
-118.324765599,
34.742340771
],
[
-118.324902701,
34.742340774
],
[
-118.324782787,
34.739791629
],
[
-118.324656399,
34.739792562
],
[
-118.321818215,
34.73983491
],
[
-118.321723743,
34.737421328
],
[
-118.318794936,
34.737463571
],
[
-118.318943061,
34.741690458
],
[
-118.315014788,
34.741751738
],
[
-118.314961133,
34.739937086
],
[
-118.311042888,
34.739996866
],
[
-118.311131734,
34.743628911
],
[
-118.307195019,
34.743692679
],
[
-118.307022176,
34.73292151
],
[
-118.307017236,
34.732701729
],
[
-118.306961869,
34.729197417
],
[
-118.311327393,
34.729174956
],
[
-118.311346965,
34.732617423
],
[
-118.3113478,
34.732644898
],
[
-118.311351901,
34.732727164
],
[
-118.315711282,
34.73267014
],
[
-118.315713308,
34.732587934
],
[
-118.315701602,
34.729152316
],
[
-118.320071884,
34.729129528
],
[
-118.320062563,
34.725505708
],
[
-118.315688277,
34.725527134
],
[
-118.315674941,
34.721907411
],
[
-118.320054027,
34.721894246
],
[
-118.320044883,
34.718366592
],
[
-118.320044698,
34.71828416
],
[
-118.318949128,
34.718285882
],
[
-118.317852726,
34.718287568
],
[
-118.316757189,
34.718289242
],
[
-118.315661616,
34.718290466
],
[
-118.315591765,
34.711052422
],
[
-118.31177053,
34.711045178
],
[
-118.306851348,
34.711035697
],
[
-118.306807821,
34.703851184
],
[
-118.306807578,
34.703768345
],
[
-118.311163994,
34.703793557
],
[
-118.311164549,
34.703710593
],
[
-118.311153205,
34.700151308
],
[
-118.315521476,
34.700168694
],
[
-118.315520836,
34.698345595
],
[
-118.315520196,
34.696522689
],
[
-118.315519752,
34.694760206
],
[
-118.315519343,
34.69294554
],
[
-118.315518911,
34.691133595
],
[
-118.315518483,
34.689349154
],
[
-118.315518511,
34.689321676
],
[
-118.315518613,
34.689225465
],
[
-118.324240593,
34.6892215
],
[
-118.324199826,
34.681929424
],
[
-118.324181765,
34.678286336
],
[
-118.324013286,
34.678286206
],
[
-118.321990626,
34.678294268
],
[
-118.319802221,
34.678302293
],
[
-118.319789286,
34.676482105
],
[
-118.319776231,
34.674800764
],
[
-118.319777068,
34.674668997
],
[
-118.324156113,
34.674640133
],
[
-118.324305833,
34.667353292
],
[
-118.324299819,
34.665534142
],
[
-118.324196404,
34.665535338
],
[
-118.319819256,
34.66554772
],
[
-118.319836703,
34.661900053
],
[
-118.321427846,
34.661592475
],
[
-118.322854394,
34.661224449
],
[
-118.324355708,
34.661602373
],
[
-118.324379145,
34.660067608
],
[
-118.322436434,
34.660073928
],
[
-118.320078162,
34.66007227
],
[
-118.319016614,
34.659630555
],
[
-118.318265028,
34.659228426
],
[
-118.317204016,
34.65892139
],
[
-118.316696353,
34.658343507
],
[
-118.316433733,
34.657886214
],
[
-118.316399174,
34.657374451
],
[
-118.316233563,
34.656701388
],
[
-118.315872914,
34.656190468
],
[
-118.315317537,
34.655922512
],
[
-118.314716272,
34.655843026
],
[
-118.314152005,
34.656042868
],
[
-118.313658715,
34.656335886
],
[
-118.31325996,
34.656463014
],
[
-118.312825923,
34.656501405
],
[
-118.312240655,
34.656360416
],
[
-118.311823758,
34.656137014
],
[
-118.311295459,
34.655640322
],
[
-118.310486705,
34.655074199
],
[
-118.309612031,
34.654525776
],
[
-118.308409437,
34.654003693
],
[
-118.307518342,
34.653679193
],
[
-118.306495295,
34.653471832
],
[
-118.306491282,
34.652731529
],
[
-118.306449169,
34.645426711
],
[
-118.304251649,
34.645432722
],
[
-118.302054126,
34.645438694
],
[
-118.299868246,
34.645445971
],
[
-118.298911338,
34.645448524
],
[
-118.298911338,
34.311655678
],
[
-118.590173754,
34.311655678
],
[
-118.590173754,
34.818203384
]
]
]
}
},
{
"type": "Feature",
"properties": {},
"geometry": {
"type": "Polygon",
"coordinates": [
[
[
-118.625390854,
34.05061708
],
[
-118.625390854,
34.311655678
],
[
-118.456022326,
34.311655678
],
[
-118.456022326,
34.05061708
],
[
-118.625390854,
34.05061708
]
]
]
}
}
]
}
最佳答案
Even if it were some great circle discrepancy, I'd expect the point to be intersecting one of the polygons, not outside both of them.
这并不总是一个有效的假设。如果多边形具有相同的边和完全相同的端点，则这将起作用。但事实并非如此，所以每个人都遵循自己的大循环。这是这里可能发生的情况的夸张版本，使用两个完全对齐为几何图形的地理(我使用 BigQuery GeoViz 来绘制它):
select 1 x, st_geogfromtext('polygon((20 20, 40 20, 40 40, 20 40, 20 20))') g1
union all
select 2, st_geogfromtext('polygon((25 40, 50 40, 50 60, 25 60, 25 40))')
正如您所看到的，当边缘遵循大圆时，两个“矩形”之间既存在重叠又存在孔。
基本上，您需要使用真正代表您所拥有的形状的类型(几何与地理)。 PostGIS 会进行正确的计算，但是当您转换为不同的类型时，可能会得到错误的结果。
如果您使用 Geometry 的原因是缺少 Geography 类型的 PostGIS ST_Subdivide，请考虑制作自己的。我已经为 BigQuery 创建了一个 ST_Subdivide 版本，可以与地理一起使用(BigQuery 缺少几何类型) - 应该可以将其移植到 PostGIS https://mentin.medium.com/subdivide-and-conquer-any-geometry-ca4f0a4b8491 .
关于postgresql - 如何准确确定边界附近的点和地理的 ST_Intersects(ST_Intersects geography vs. Geometry diffrepancy)，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/76665124/