计算包含地理坐标的字符串的边界框

Question

我从googlemapsdirectionsapi计算了linestring。 我把线串转换成GeoGeometry对象。我需要另一个区域，覆盖距离linestring对象“d”的所有点。 距离以m，km为单位。 GEOS API提供geosometry.buffer（width，quadsegs=8）这样做在二维投影中效果很好。在

但对于球形模型，该怎么做呢？是否与SRID有关。在

from django.contrib.gis.geos import LineString
from django.contrib.gis.geos import GEOSGeometry

directions = maps_client.directions(source, destination)
overview_polyline = decode_polyline(directions[0]['overview_polyline'])

linestring_obj = LineString(overview_polyline)

# FOR 2-D projection
bounding_box = linestring_obj.buffer(width=100) 

# For spherical model
# ???

Answer 1

为了使以米为单位的地理距离有意义，您必须始终通过投影坐标系，因此我建议您将数据转换为投影坐标系，创建缓冲区并将其投影回去。例如：

# Specify the original srid of your data
orig_srid = 4326

# Create the linestring with the correct srid
linestring_obj = LineString(overview_polyline, srid=orig_srid)

# Transform (project) the linestring into a projected coorinate system
linestring_obj.transform(3857)

# Compute bbox in in that system
bounding_box = linestring_obj.buffer(width=100)

# Transform bounding box into the original coorinate system of your data
bounding_box.transform(orig_srid)