Question

我想使用底图来绘制地图，但找不到如何在地图上绘制UTM网格。

我已经看过如何使用long / lat绘制网格，但未在UTM中绘制。在底图y中，使用epsg = 5520（UTM 31N）。

m = Basemap(epsg=5520, llcrnrlat=52, llcrnrlon=5,urcrnrlat=53, urcrnrlon=6, resolution='l')

m.arcgisimage(server='http://server.arcgisonline.com/arcgis',
              service='World_Imagery', xpixels=3500)
m.drawparallels(np.arange(52, 53, 0.05), labels=[1, 0, 0, 0])
m.drawmeridians(np.arange(5, 6, 0.05), labels=[0, 0, 0, 1])

关于如何实现UTM网格的任何想法？

Answer 1

使用底图时，在UTM地图投影上绘制UTM格线或刻度线并不容易，因为底图的数据坐标（从长纬度转换）偏离了实际的UTM值。因此，为了从（long，lat）得到适当的（x，y），我使用pyproj包。在提供的代码中，命令plot()用于绘制所有网格刻度。 annotate()用于在地图区域外绘制网格标签。网格标签的值需要乘以10000才能获得metres单位。

这是工作代码：

from mpl_toolkits.basemap import Basemap
import matplotlib.pyplot as plt
import numpy as np
import pyproj

# need pyproj package for coordinate tranformation
pp = pyproj.Proj(init='epsg:5520')

# use map's corners (long,lat) to get grid coordinates (x,y)
corners = [[5,52], [5,53], [6.2, 53], [5.95, 51.5]]
for ea in corners:
    x,y = pp(ea[0],ea[1])  #(long,lat) to (x,y)
    lon,lat = pp(x, y, inverse=True)
    print(x, y, "%4.1f"%(lon), "%4.1f"%(lat))

# the output of print() above, give extents in grid coordinates
#x range: 1630000, 1720000 m -> 1630, 1720 km
#y range: 5710000, 5900000 m -> 5710, 5900 km

low_x, hi_x = 1630000, 1720000
low_y, hi_y = 5710000, 5900000
grid_sp = 10000   # 10km grid spacing

# we will plot grid ticks '+' at 10km spacing
# .. inside the plotting area
lon_lat = []   # for positions of grid ticks '+'
for ea in np.arange(low_x, hi_x, grid_sp):      # xs
    for eb in np.arange(low_y, hi_y, grid_sp):  # ys
        lon,lat = pp(ea, eb, inverse=True)
        #print(ea, eb, lon, lat)
        # lon, lat is good for plotting on basemap
        lon_lat.append([lon,lat])

# for annotation above top edge, every 10km
yt = 5870000   # y at top edge of map
xs_top = []    # for labels' positions of x grid
for xi in np.arange(low_x, hi_x, grid_sp):   # xs
    lon,lat = pp(xi, yt, inverse=True)
    #print(ea, eb, lon, lat)
    xs_top.append([lon,lat])

# make anno text for every 10 km along map's top edge
anno_top = map(str, list(range(low_x/grid_sp, hi_x/grid_sp)))

# for annotation to the right, every 10km
xr = 1700000   # x at the right edge of map
ys_rt = []     # for labels' positions of y grid
for yi in np.arange(low_y, hi_y, grid_sp):   # ys
    lon,lat = pp(xr, yi, inverse=True)
    #print(xr, yi, lon, lat)
    ys_rt.append([lon,lat])

# make anno text for every 10 km along map's right edge
anno_rt = map(str, list(range(low_y/grid_sp, hi_y/grid_sp))) 

# prep fig/axes for Basemap plot
fig, ax = plt.subplots(figsize=(10, 12))

m = Basemap(epsg=5520, llcrnrlat=52, llcrnrlon=5, urcrnrlat=53, urcrnrlon=6, resolution='i')

# option to plot imagery, need internet connection
if True:
    server = 'http://server.arcgisonline.com/arcgis'
    m.arcgisimage(server=server, service='World_Imagery', xpixels=1500)

# plot grid ticks '+' inside map area
m.plot(np.array(lon_lat)[:,0], np.array(lon_lat)[:,1], 'w+', latlon=True, zorder=10)

# option to plot grid labels on top/right edges
if True:
    # grid labels on top edge
    for id,ea in enumerate(xs_top):
        if ea[0]>5.0 and ea[0]<6.0:
            ax.annotate(anno_top[id], \
                        m(ea[0], ea[1]), \
                        xytext=[-8,50], \
                        textcoords='offset points', \
                        color='b')
            pass
        pass

    # grid labels on right edge
    for id,ea in enumerate(ys_rt):
        if ea[1]>52.0 and ea[1]<53.0:
            ax.annotate(anno_rt[id], \
                        m(ea[0], ea[1]), \
                        xytext=[10,-5], \
                        textcoords='offset points', \
                        color='b')
            pass
        pass

#m.drawcoastlines(linewidth=0.25)
#m.fillcontinents(color='lightgray')

m.drawparallels(np.arange(52, 53.1, 0.1), labels=[1, 0, 0, 0])
m.drawmeridians(np.arange(5, 6, 0.1), labels=[0, 0, 0, 1])
plt.show()

结果图：

地图绘图网格问题

1 个答案: