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Aligning Raster and vector layer using PyQGIS when they do not match?
Planned maintenance scheduled April 23, 2019 at 23:30 UTC (7:30pm US/Eastern)
Announcing the arrival of Valued Associate #679: Cesar Manara
Unicorn Meta Zoo #1: Why another podcast?PyQGIS raster image shifted from vector shapefileCreating memory layer with .png image using PyQGIS?Generate centroids for vector polygons based on raster and land-use data using QGISPlanar CRS for raster and vector layersRaster and vector layer in the same CRS don't matchMerging raster and vector not workingChanging origin (top left corner) coordinates of raster using PyQGIS?Align two georreferenced rasters which have different resolution in QGISIs raster lossy and vector not lossy?Raster with wrong extents when using Polygon to RasterWhy are my vector layers with different CRS not aligning?Creating memory layer with .png image using PyQGIS?
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Relatively new to GIS. I've created a vector layer of points based on row/col position of high population density pixels in a raster layer. The layers do not align even though they have the same CRS, presumably because they do not have the same extent.
Is it possible to edit the extent of the raster to match that of the vector layer or when creating the new vector layer can I define extent based on my raster layer?
raster coordinate-system pyqgis vector
add a comment |
Relatively new to GIS. I've created a vector layer of points based on row/col position of high population density pixels in a raster layer. The layers do not align even though they have the same CRS, presumably because they do not have the same extent.
Is it possible to edit the extent of the raster to match that of the vector layer or when creating the new vector layer can I define extent based on my raster layer?
raster coordinate-system pyqgis vector
If my answer solved your issue you should mark it as accepted.
– xunilk
Apr 28 '17 at 21:17
add a comment |
Relatively new to GIS. I've created a vector layer of points based on row/col position of high population density pixels in a raster layer. The layers do not align even though they have the same CRS, presumably because they do not have the same extent.
Is it possible to edit the extent of the raster to match that of the vector layer or when creating the new vector layer can I define extent based on my raster layer?
raster coordinate-system pyqgis vector
Relatively new to GIS. I've created a vector layer of points based on row/col position of high population density pixels in a raster layer. The layers do not align even though they have the same CRS, presumably because they do not have the same extent.
Is it possible to edit the extent of the raster to match that of the vector layer or when creating the new vector layer can I define extent based on my raster layer?
raster coordinate-system pyqgis vector
raster coordinate-system pyqgis vector
edited Apr 12 at 20:52
PolyGeo♦
54.1k1782246
54.1k1782246
asked Apr 13 '17 at 20:22
SimonSimon
343
343
If my answer solved your issue you should mark it as accepted.
– xunilk
Apr 28 '17 at 21:17
add a comment |
If my answer solved your issue you should mark it as accepted.
– xunilk
Apr 28 '17 at 21:17
If my answer solved your issue you should mark it as accepted.
– xunilk
Apr 28 '17 at 21:17
If my answer solved your issue you should mark it as accepted.
– xunilk
Apr 28 '17 at 21:17
add a comment |
1 Answer
1
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oldest
votes
To do that you need to get simultaneously x,y coordinates of each point by using some raster parameters (as xmin, ymax, and x, y resolution). Next code uses these parameters for obtaining a point memory layer where each point is situated at the middle of each raster cell.
layer = iface.activeLayer()
provider = layer.dataProvider()
extent = layer.extent()
xmin,ymin,xmax,ymax = extent.toRectF().getCoords()
rows = layer.height()
cols = layer.width()
xSize = layer.rasterUnitsPerPixelX()
ySize = layer.rasterUnitsPerPixelY()
block = provider.block(1, extent, cols, rows)
xinit = xmin + xSize/2
yinit = ymax - ySize/2
x = xinit
y = yinit
points = []
values = []
for i in range(rows):
for j in range(cols):
value = block.value(i,j)
if value > 150 and value < 255:
points.append(QgsPoint(x,y))
values.append(value)
x += xSize
y -= ySize
x = xinit
epsg = layer.crs().postgisSrid()
uri = "Point?crs=epsg:" + str(epsg) + "&field=id:integer&field=value:integer""&index=yes"
mem_layer = QgsVectorLayer(uri,
'point',
'memory')
prov = mem_layer.dataProvider()
feats = [ QgsFeature() for i in range(len(points)) ]
for i, feat in enumerate(feats):
feat.setAttributes([i, values[i]])
feat.setGeometry(QgsGeometry.fromPoint(points[i]))
prov.addFeatures(feats)
QgsMapLayerRegistry.instance().addMapLayer(mem_layer)
I used this population raster; where the criterion to get points was they represent values greater than 150 (254 = 10,000 persons/km2 and 255 = No data). After running the code at Python Console of QGIS I got:
Points over raster match as expected.
add a comment |
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1 Answer
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1 Answer
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active
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votes
To do that you need to get simultaneously x,y coordinates of each point by using some raster parameters (as xmin, ymax, and x, y resolution). Next code uses these parameters for obtaining a point memory layer where each point is situated at the middle of each raster cell.
layer = iface.activeLayer()
provider = layer.dataProvider()
extent = layer.extent()
xmin,ymin,xmax,ymax = extent.toRectF().getCoords()
rows = layer.height()
cols = layer.width()
xSize = layer.rasterUnitsPerPixelX()
ySize = layer.rasterUnitsPerPixelY()
block = provider.block(1, extent, cols, rows)
xinit = xmin + xSize/2
yinit = ymax - ySize/2
x = xinit
y = yinit
points = []
values = []
for i in range(rows):
for j in range(cols):
value = block.value(i,j)
if value > 150 and value < 255:
points.append(QgsPoint(x,y))
values.append(value)
x += xSize
y -= ySize
x = xinit
epsg = layer.crs().postgisSrid()
uri = "Point?crs=epsg:" + str(epsg) + "&field=id:integer&field=value:integer""&index=yes"
mem_layer = QgsVectorLayer(uri,
'point',
'memory')
prov = mem_layer.dataProvider()
feats = [ QgsFeature() for i in range(len(points)) ]
for i, feat in enumerate(feats):
feat.setAttributes([i, values[i]])
feat.setGeometry(QgsGeometry.fromPoint(points[i]))
prov.addFeatures(feats)
QgsMapLayerRegistry.instance().addMapLayer(mem_layer)
I used this population raster; where the criterion to get points was they represent values greater than 150 (254 = 10,000 persons/km2 and 255 = No data). After running the code at Python Console of QGIS I got:
Points over raster match as expected.
add a comment |
To do that you need to get simultaneously x,y coordinates of each point by using some raster parameters (as xmin, ymax, and x, y resolution). Next code uses these parameters for obtaining a point memory layer where each point is situated at the middle of each raster cell.
layer = iface.activeLayer()
provider = layer.dataProvider()
extent = layer.extent()
xmin,ymin,xmax,ymax = extent.toRectF().getCoords()
rows = layer.height()
cols = layer.width()
xSize = layer.rasterUnitsPerPixelX()
ySize = layer.rasterUnitsPerPixelY()
block = provider.block(1, extent, cols, rows)
xinit = xmin + xSize/2
yinit = ymax - ySize/2
x = xinit
y = yinit
points = []
values = []
for i in range(rows):
for j in range(cols):
value = block.value(i,j)
if value > 150 and value < 255:
points.append(QgsPoint(x,y))
values.append(value)
x += xSize
y -= ySize
x = xinit
epsg = layer.crs().postgisSrid()
uri = "Point?crs=epsg:" + str(epsg) + "&field=id:integer&field=value:integer""&index=yes"
mem_layer = QgsVectorLayer(uri,
'point',
'memory')
prov = mem_layer.dataProvider()
feats = [ QgsFeature() for i in range(len(points)) ]
for i, feat in enumerate(feats):
feat.setAttributes([i, values[i]])
feat.setGeometry(QgsGeometry.fromPoint(points[i]))
prov.addFeatures(feats)
QgsMapLayerRegistry.instance().addMapLayer(mem_layer)
I used this population raster; where the criterion to get points was they represent values greater than 150 (254 = 10,000 persons/km2 and 255 = No data). After running the code at Python Console of QGIS I got:
Points over raster match as expected.
add a comment |
To do that you need to get simultaneously x,y coordinates of each point by using some raster parameters (as xmin, ymax, and x, y resolution). Next code uses these parameters for obtaining a point memory layer where each point is situated at the middle of each raster cell.
layer = iface.activeLayer()
provider = layer.dataProvider()
extent = layer.extent()
xmin,ymin,xmax,ymax = extent.toRectF().getCoords()
rows = layer.height()
cols = layer.width()
xSize = layer.rasterUnitsPerPixelX()
ySize = layer.rasterUnitsPerPixelY()
block = provider.block(1, extent, cols, rows)
xinit = xmin + xSize/2
yinit = ymax - ySize/2
x = xinit
y = yinit
points = []
values = []
for i in range(rows):
for j in range(cols):
value = block.value(i,j)
if value > 150 and value < 255:
points.append(QgsPoint(x,y))
values.append(value)
x += xSize
y -= ySize
x = xinit
epsg = layer.crs().postgisSrid()
uri = "Point?crs=epsg:" + str(epsg) + "&field=id:integer&field=value:integer""&index=yes"
mem_layer = QgsVectorLayer(uri,
'point',
'memory')
prov = mem_layer.dataProvider()
feats = [ QgsFeature() for i in range(len(points)) ]
for i, feat in enumerate(feats):
feat.setAttributes([i, values[i]])
feat.setGeometry(QgsGeometry.fromPoint(points[i]))
prov.addFeatures(feats)
QgsMapLayerRegistry.instance().addMapLayer(mem_layer)
I used this population raster; where the criterion to get points was they represent values greater than 150 (254 = 10,000 persons/km2 and 255 = No data). After running the code at Python Console of QGIS I got:
Points over raster match as expected.
To do that you need to get simultaneously x,y coordinates of each point by using some raster parameters (as xmin, ymax, and x, y resolution). Next code uses these parameters for obtaining a point memory layer where each point is situated at the middle of each raster cell.
layer = iface.activeLayer()
provider = layer.dataProvider()
extent = layer.extent()
xmin,ymin,xmax,ymax = extent.toRectF().getCoords()
rows = layer.height()
cols = layer.width()
xSize = layer.rasterUnitsPerPixelX()
ySize = layer.rasterUnitsPerPixelY()
block = provider.block(1, extent, cols, rows)
xinit = xmin + xSize/2
yinit = ymax - ySize/2
x = xinit
y = yinit
points = []
values = []
for i in range(rows):
for j in range(cols):
value = block.value(i,j)
if value > 150 and value < 255:
points.append(QgsPoint(x,y))
values.append(value)
x += xSize
y -= ySize
x = xinit
epsg = layer.crs().postgisSrid()
uri = "Point?crs=epsg:" + str(epsg) + "&field=id:integer&field=value:integer""&index=yes"
mem_layer = QgsVectorLayer(uri,
'point',
'memory')
prov = mem_layer.dataProvider()
feats = [ QgsFeature() for i in range(len(points)) ]
for i, feat in enumerate(feats):
feat.setAttributes([i, values[i]])
feat.setGeometry(QgsGeometry.fromPoint(points[i]))
prov.addFeatures(feats)
QgsMapLayerRegistry.instance().addMapLayer(mem_layer)
I used this population raster; where the criterion to get points was they represent values greater than 150 (254 = 10,000 persons/km2 and 255 = No data). After running the code at Python Console of QGIS I got:
Points over raster match as expected.
answered Apr 14 '17 at 11:52
xunilkxunilk
15k31943
15k31943
add a comment |
add a comment |
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If my answer solved your issue you should mark it as accepted.
– xunilk
Apr 28 '17 at 21:17