接着写一个矢量切片的http服务(参考go-vtile-example,这个例子中矢量切片压缩率更高),并且使用mapbox进行前端展示(小贴士:sql中‘points’的字符串与渲染中mapbox里的source-layer一致).代码见最下方 SELECTST_AsMVT(tile,'points') tile FROM( SELECTST_AsMVTGeom(geom,ST_MakeEnvelope(100,10,125,22,4326),4...
ST_Distance—返回两个几何或地理值之间的距离。 ST_Distance— Returns the distance between two geometry or geography values. ST_3DDistance—以投影单位返回两个几何之间的3D笛卡尔最小距离(基于空间参考)。 ST_3DDistance— Returns the 3D cartesian minimum distance (based on spatial ref) between two geome...
st_geometryfromtext(geometry,srid):该方法作用是根据描述的几何对象(geometry)的字符串转化成几何对象,POINT说明几何对象是点类型,第二个参数srid是4326,是指这个点类型对象的空间参考(也就是EPSG的编号,也是所在的坐标系)是EPSG:4326,即WGS84大地坐标系。 st_transform(geometry,srid):该方法是把某个几何对象(geo...
可以通过SQL语句创建这些空间数据对象。使用ST_MakePoint、ST_MakeLine、ST_MakePolygon等函数,可以创建对应的空间数据。这些数据将成为可视化的基础。 CREATE TABLE cities ( id SERIAL PRIMARY KEY, name VARCHAR(50), geom GEOMETRY(Point, 4326) ); INSERT INTO cities (name, geom) VALUES ('San Francisco', ...
st_transform(geometry,srid):该方法是把某个几何对象(geometry)的所有坐标从一个坐标系转换到另一个坐标系。在这做的就是把EPSG:4326转换为EPSG:4527(量北京的尺子到手)。 st_distance(geometry,geometry):该方法用于计算两点距离,所用坐标系根据geometry带的srid(EPSG编号)决定。
center = 'POINT(lon lat)'; center = REPLACE(center, 'lon', lon :: TEXT); center = REPLACE(center, 'lat', lat :: TEXT); circle = ST_Buffer(ST_GeomFromText(center,4326)::geography, radius*1.8527*1000) :: geography; trigle = ST_Polygon('LINESTRING(' || lon || ' ' || lat...
查看PostgrelSQL的官方手册(ST_GeogFromText)关于函数的解释如下: 初步怀疑是mybatis参数传递导致,将’POINT()'部分整个作为参数传递,修改后SQL如下: AND ST_Intersects ( ST_Buffer (ST_GeomFromText (${geog.centerString}, ${geog.srid}) :: geography, ${geog.radiusMetre} ) :: geography, position )...
ST_Box2dFromGeoHash Return a BOX2D from a GeoHash string. //语法 box2d ST_Box2dFromGeoHash(text geohash, integer precision=full_precision_of_geohash); //示例 SELECT ST_Box2dFromGeoHash('9qqj7nmxncgyy4d0dbxqz0'); st_geomfromgeohash --- BOX(-115.172816 36.114646,-115.172816 36.114646...
use rgdal::readOGR or sf::st_read china_map@data ggplot2::fortify(china_map) geojsonio包导入: system.time(geojson1 <- geojson_read( "D:/R/rstudy/CHN_adm/bou2_4p.shp", method = "local", parse = TRUE, what = "sp",
use rgdal::readOGR or sf::st_read china_map@data ggplot2::fortify(china_map) geojsonio包导入: system.time(geojson1 <- geojson_read( "D:/R/rstudy/CHN_adm/bou2_4p.shp", method ="local", parse = TRUE, what ="sp", encoding="utf-8", ...