OGR常量表示的不同幾何類型
雖然許多幾何要素只存在于二維(2D)的直角坐標系平面(X和Y坐標)，也有三維(3D)帶有Z值得幾何對象。這些Z值通常用來表示高程，但也可以用于表示其它數據，如每年溫度得最大值。從技術上講，這些幾何要素在OGR中被認為是2.5D，而不是3D，因為OGR進行空間操作時，不考慮Z值。注意，雖然可以將Z值添加到二維幾何結構中，但將數據寫入文件時，Z值將被忽略。

from osgeo import ogr ogr.Geometry(ogr.wkbPoint) 幾何類型2D常量2.5常量

點	wkbPoint	wkbPoint25D
多點	wkbMultiPoint	wkbMultiPoint25D
線	wkbLineString	wkbLineString25D
多線	wkbMultiLineString	wkbMultiLineString25D
多邊形環	wkbLinearRing	n/a
面	wkbPolygon	wkbPolygon25D
多面	wkbMultiPolygon	wkbMultiPolygon25D
幾何集合	wkbGeometryCollection	wkbGeometryCollection25D

處理點集

創建并編輯一個點

from osgeo import ogr from ospybook.vectorplotter import VectorPlotter firepit = ogr.Geometry(ogr.wkbPoint)firepit.AddPoint(59.5,11.5) print(firepit)x,y = firepit.GetX(), firepit.GetY() print(str(x)+','+str(y))vp = VectorPlotter(True) vp.plot(firepit,'bo') POINT (59.5 11.5 0) 59.5,11.5

更改一個已經存在的點

from osgeo import ogr from ospybook.vectorplotter import VectorPlotter firepit = ogr.Geometry(ogr.wkbPoint)firepit.AddPoint(59.5,11.5) print(firepit)x,y = firepit.GetX(), firepit.GetY() print(str(x)+','+str(y))# 更改點坐標 firepit.AddPoint(59.5,13) print(firepit)x,y = firepit.GetX(), firepit.GetY() print(str(x)+','+str(y))vp = VectorPlotter(True) vp.plot(firepit,'rs') POINT (59.5 11.5 0) 59.5,11.5 POINT (59.5 13.0 0) 59.5,13.0

創建一個2.5D的點

from osgeo import ogr from ospybook.vectorplotter import VectorPlotter firepit = ogr.Geometry(ogr.wkbPoint25D)firepit.AddPoint(59.5,11.5,2) print(firepit)x,y,z = firepit.GetX(), firepit.GetY(), firepit.GetZ() print(str(x)+','+str(y) + ','+str(z))vp = VectorPlotter(True) vp.plot(firepit,'bo') POINT (59.5 11.5 2) 59.5,11.5,2.0

多點作為一個幾何類型

from osgeo import ogr from ospybook.vectorplotter import VectorPlotter faucets = ogr.Geometry(ogr.wkbMultiPoint) faucet = ogr.Geometry(ogr.wkbPoint) faucet.AddPoint(67.5, 16) faucets.AddGeometry(faucet) # 添加到多點對象 faucet.AddPoint(73,31) faucets.AddGeometry(faucet) # 添加到多點對象 faucet.AddPoint(91,24.5) faucets.AddGeometry(faucet) # 添加到多點對象#vp.clear() vp.plot(faucets,'bo') vp.zoom(-5) print(faucets) MULTIPOINT (67.5 16.0 0,73 31 0,91.0 24.5 0)

for i in range(faucets.GetGeometryCount()):pt = faucets.GetGeometryRef(i)pt.AddPoint(pt.GetX() + 2, pt.GetY())vp.plot(faucets,'rs') vp.zoom(-5)

處理線要素

創建并編輯單條線

from osgeo import ogr from ospybook.vectorplotter import VectorPlottersidewalk = ogr.Geometry(ogr.wkbLineString) sidewalk.AddPoint(54, 37) sidewalk.AddPoint(62, 35.5) sidewalk.AddPoint(70.5, 38) sidewalk.AddPoint(74.5, 41.5)vp.plot(sidewalk,'b--') print(sidewalk) LINESTRING (54 37 0,62.0 35.5 0,70.5 38.0 0,74.5 41.5 0)

for i in range(sidewalk.GetPointCount()):sidewalk.SetPoint(i,sidewalk.GetX(i), sidewalk.GetY(i)+1)vp.plot(sidewalk,'r--')

print(sidewalk.GetPoints()) [(54.0, 38.0, 0.0), (62.0, 36.5, 0.0), (70.5, 39.0, 0.0), (74.5, 42.5, 0.0)] vertices = sidewalk.GetPoints() vertices[2:2] = [(66.5,35)] print(vertices)new_sidewalk = ogr.Geometry(ogr.wkbLineString) for vertex in vertices:new_sidewalk.AddPoint(*vertex)vp.plot(new_sidewalk,'g:') [(54.0, 38.0, 0.0), (62.0, 36.5, 0.0), (66.5, 35), (70.5, 39.0, 0.0), (74.5, 42.5, 0.0)]

import osdata_dir = "D:\中國交通通信信息中心\書籍配套代碼\python地理數據處理\資源\osgeopy-data\osgeopy-data\osgeopy-data-misc\osgeopy-data" ds = ogr.Open(os.path.join(data_dir, 'misc', 'line-example.geojson')) lyr = ds.GetLayer() feature = lyr.GetFeature(0) line = feature.geometry().Clone() vp.clear() vp.plot(line, 'b-')

from osgeo import ogr from ospybook.vectorplotter import VectorPlotter import os data_dir = "D:\中國交通通信信息中心\書籍配套代碼\python地理數據處理\資源\osgeopy-data\osgeopy-data\osgeopy-data-misc\osgeopy-data" ds = ogr.Open(os.path.join(data_dir, 'misc', 'line-example.geojson')) lyr = ds.GetLayer() feature = lyr.GetFeature(0) line = feature.geometry().Clone()vertices = line.GetPoints() vertices = line.GetPoints() vertices[26:26] = [(87, 57)] vertices[19:19] = [(95, 38), (97, 43), (101, 42)] vertices[11:11] = [(121, 18)] vertices[5:5] = [(67, 32), (74, 30)] new_line = ogr.Geometry(ogr.wkbLineString) for vertex in vertices:new_line.AddPoint(*vertex) vp.plot(new_line, 'b--')

線創建點

def line_to_point_layer(ds, line_name, pt_name):"""Creates a point layer from vertices in a line layer."""# Delete the point layer if it exists.if ds.GetLayer(pt_name):ds.DeleteLayer(pt_name)# Get the line layer and its spatial reference.line_lyr = ds.GetLayer(line_name)sr = line_lyr.GetSpatialRef()# Create a point layer with the same SR as the lines# and copy the field definitions from the line to# the point layer.pt_lyr = ds.CreateLayer(pt_name, sr, ogr.wkbPoint)pt_lyr.CreateFields(line_lyr.schema)# Create a feature and geometry to use over and over.pt_feat = ogr.Feature(pt_lyr.GetLayerDefn())pt_geom = ogr.Geometry(ogr.wkbPoint)# Loop through all of the lines.for line_feat in line_lyr:# Copy the attribute values from the line to the# new feature.atts = line_feat.items()for fld_name in atts.keys():pt_feat.SetField(fld_name, atts[fld_name])# Loop through the line's vertices and for each one,# set the coordinates on the point geometry, add# it to the feature, and use the feature to create# a new feature in the point layer.for coords in line_feat.geometry().GetPoints():pt_geom.AddPoint(*coords)pt_feat.SetGeometry(pt_geom)pt_lyr.CreateFeature(pt_feat)from osgeo import ogr from ospybook.vectorplotter import VectorPlotter import os import ospybook as pb data_dir = "D:\中國交通通信信息中心\書籍配套代碼\python地理數據處理\資源\osgeopy-data\osgeopy-data\osgeopy-data-misc\osgeopy-data" ds = ogr.Open(os.path.join(data_dir, 'misc', 'line-example.geojson')) lyr = ds.GetLayer() feature = lyr.GetFeature(0) line = feature.geometry().Clone()pb.print_layers(os.path.join(data_dir, 'misc', 'line-example.geojson')) 0: line-example (LineString)

多線作為一個幾何類型

from osgeo import ogr from ospybook.vectorplotter import VectorPlotterpath1 = ogr.Geometry(ogr.wkbLineString) path1.AddPoint(61.5, 29) path1.AddPoint(63, 20) path1.AddPoint(62.5, 16) path1.AddPoint(60, 13)path2 = ogr.Geometry(ogr.wkbLineString) path2.AddPoint(60.5, 12) path2.AddPoint(68.5, 13.5)path3 = ogr.Geometry(ogr.wkbLineString) path3.AddPoint(69.5, 33) path3.AddPoint(80, 33) path3.AddPoint(86.5, 22.5)paths = ogr.Geometry(ogr.wkbMultiLineString) paths.AddGeometry(path1) paths.AddGeometry(path2) paths.AddGeometry(path3)# Take a look at the multiline. vp.clear() vp.plot(paths, 'b-') print(paths) MULTILINESTRING ((61.5 29.0 0,63 20 0,62.5 16.0 0,60 13 0),(60.5 12.0 0,68.5 13.5 0),(69.5 33.0 0,80 33 0,86.5 22.5 0))

處理多邊形

創建并編輯單多邊形

from osgeo import ogr from ospybook.vectorplotter import VectorPlotterring = ogr.Geometry(ogr.wkbLinearRing) ring.AddPoint(58, 38.5) ring.AddPoint(53, 6) ring.AddPoint(99.5, 19) ring.AddPoint(73, 42) yard = ogr.Geometry(ogr.wkbPolygon) yard.AddGeometry(ring) yard.CloseRings()# Take a look at the polygon. Setting fill=False makes the polygon hollow when # it is drawn. vp = VectorPlotter(True) vp.plot(yard, fill=False, edgecolor='blue') print(yard) POLYGON ((58.0 38.5 0,53 6 0,99.5 19.0 0,73 42 0,58.0 38.5 0))

ring = yard.GetGeometryRef(0) for i in range(ring.GetPointCount()):ring.SetPoint(i, ring.GetX(i) - 5, ring.GetY(i)) vp.plot(yard, fill=False, ec='red', linestyle='dashed')

ring = yard.GetGeometryRef(0) vertices = ring.GetPoints() vertices[2:3] = ((90, 16), (90, 27)) for i in range(len(vertices)):ring.SetPoint(i, *vertices[i]) vp.plot(yard, fill=False, ec='black', ls='dotted', linewidth=3)

從多邊形創建線

def poly_to_line_layer(ds, poly_name, line_name):"""Creates a line layer from a polygon layer."""# Delete the line layer if it exists.if ds.GetLayer(line_name):ds.DeleteLayer(line_name)# Get the polygon layer and its spatial reference.poly_lyr = ds.GetLayer(poly_name)sr = poly_lyr.GetSpatialRef()# Create a line layer with the same SR as the polygons# and copy the field definitions from the polygons to# the line layer.line_lyr = ds.CreateLayer(line_name, sr, ogr.wkbLineString)line_lyr.CreateFields(poly_lyr.schema)# Create a feature to use over and over.line_feat = ogr.Feature(line_lyr.GetLayerDefn())# Loop through all of the polygons.for poly_feat in poly_lyr:# Copy the attribute values from the polygon to the# new feature.atts = poly_feat.items()for fld_name in atts.keys():line_feat.SetField(fld_name, atts[fld_name])# Loop through the rings in the polygon.poly_geom = poly_feat.geometry()for i in range(poly_geom.GetGeometryCount()):ring = poly_geom.GetGeometryRef(i)# Create a new line using the ring's vertices.line_geom = ogr.Geometry(ogr.wkbLineString)for coords in ring.GetPoints():line_geom.AddPoint(*coords)# Insert the new line feature.line_feat.SetGeometry(line_geom)line_lyr.CreateFeature(line_feat)

復合多邊形形成一個幾何類型

from osgeo import ogr from ospybook.vectorplotter import VectorPlotterbox1 = ogr.Geometry(ogr.wkbLinearRing) box1.AddPoint(87.5, 25.5) box1.AddPoint(89, 25.5) box1.AddPoint(89, 24) box1.AddPoint(87.5, 24) garden1 = ogr.Geometry(ogr.wkbPolygon) garden1.AddGeometry(box1)box2 = ogr.Geometry(ogr.wkbLinearRing) box2.AddPoint(89, 23) box2.AddPoint(92, 23) box2.AddPoint(92,22) box2.AddPoint(89,22) garden2 = ogr.Geometry(ogr.wkbPolygon) garden2.AddGeometry(box2)gardens = ogr.Geometry(ogr.wkbMultiPolygon) gardens.AddGeometry(garden1) gardens.AddGeometry(garden2) gardens.CloseRings()# Take a look at the multipolygon. vp.clear() vp.plot(gardens, fill=False, ec='blue') vp.zoom(-1) print(gardens) MULTIPOLYGON (((87.5 25.5 0,89.0 25.5 0,89 24 0,87.5 24.0 0,87.5 25.5 0)),((89 23 0,92 23 0,92 22 0,89 22 0,89 23 0)))

創建并編輯帶洞多邊形：甜甜圈

from osgeo import ogr from ospybook.vectorplotter import VectorPlotterlot = ogr.Geometry(ogr.wkbLinearRing) lot.AddPoint(58, 38.5) lot.AddPoint(53, 6) lot.AddPoint(99.5, 19) lot.AddPoint(73, 42)house = ogr.Geometry(ogr.wkbLinearRing) house.AddPoint(67.5, 29) house.AddPoint(69, 25.5) house.AddPoint(64, 23) house.AddPoint(69, 15) house.AddPoint(82.5, 22) house.AddPoint(76, 31.5)yard = ogr.Geometry(ogr.wkbPolygon) yard.AddGeometry(lot) yard.AddGeometry(house) yard.CloseRings()# Take a look at the polygon. vp.clear() vp.plot(yard, 'yellow') print(yard) POLYGON ((58.0 38.5 0,53 6 0,99.5 19.0 0,73 42 0,58.0 38.5 0),(67.5 29.0 0,69.0 25.5 0,64 23 0,69 15 0,82.5 22.0 0,76.0 31.5 0,67.5 29.0 0))

for i in range(yard.GetGeometryCount()):ring = yard.GetGeometryRef(i)for j in range(ring.GetPointCount()):ring.SetPoint(j, ring.GetX(j) - 5, ring.GetY(j)) vp.plot(yard, fill=False, hatch='x', color='blue')

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