我正在考虑使用django (2.0.6)和Postgres/postGIS作为后端(10/2.4?)。
然而,我打算使用的模型几何图形将不会存储在椭球体(无论是地球火星等)或任何其他类型的SRID上。而是在3D笛卡尔坐标中100%纯几何,其中1个单位=1米。
如何声明模型字段并确保它们都是纯几何:
数据库级别的
这样行得通吗?
geometry = models.MultiPolygonField(_('Geometry'), spatial_index=True, dim=3)
或者设置SRID更好?:
geometry = models.MultiPolygonField(_('Geometry'), spatial_index=True, dim=3, srid=0)
非常感谢
发布于 2018-06-13 03:31:29
对于1m笛卡尔网格,可以使用SRID 3857:
models.py
class Place(models.Model):
geom = models.PointField(srid=3857, dim=3)
def __str__(self):
return str(self.geom.coords)
但是,GeoDjango不支持开箱即用的三维距离计算。例如:
from django.contrib.gis.geos import Point
from django.contrib.gis.measure import Distance
from myapp.models import Place
p = Point(100, 100, 0)
Place.objects.create(geom=p)
Place.objects.create(geom=Point(150, 100, 0))
Place.objects.create(geom=Point(100, 100, 22))
Place.objects.create(geom=Point(100, 100, 500))
Place.objects.create(geom=Point(150, 150, 0))
Place.objects.create(geom=Point(250, 250, 0))
for o in Place.objects.filter(geom__distance_lte=(p, Distance(m=100))):
print(o.geom.coords, p.distance(o.geom))
输出:
(100.0, 100.0, 0.0) 0.0
(150.0, 100.0, 0.0) 50.0
(100.0, 100.0, 22.0) 0.0
(100.0, 100.0, 500.0) 0.0
(150.0, 150.0, 0.0) 70.71067811865476
在纯PostGIS中,比较ST_Distance
和ST_3DDistance
:
SELECT *
FROM (
SELECT
"myapp_place"."id",
ST_Distance("myapp_place"."geom",
ST_GeomFromEWKT('SRID=3857;POINT(100 100 0)')) d,
ST_AsEWKT("myapp_place"."geom")
FROM "myapp_place"
) t
WHERE d <= 100.0
与
SELECT *
FROM (
SELECT
"myapp_place"."id",
ST_3DDistance("myapp_place"."geom",
ST_GeomFromEWKT('SRID=3857;POINT(100 100 0)')) d,
ST_AsEWKT("myapp_place"."geom")
FROM "myapp_place"
) t
WHERE d <= 100.0
https://stackoverflow.com/questions/50786126
复制相似问题