Errno 32：使用 getMapId() 时 pipe 损坏

Question

我正在阅读一个包含数千座建筑物足迹的大型 geojson 文件。 该文件如下所示：

{
  "type":"FeatureCollection",
  "features":
  [
    {"type":"Feature","geometry":{"type":"Polygon","coordinates":[[[-97.208203,50.90649],[-97.208203,50.906568],[-97.208367,50.906568],[-97.208367,50.90649],[-97.208203,50.90649]]]},"properties":{}},
    {"type":"Feature","geometry":{"type":"Polygon","coordinates":[[[-97.138545,50.91915],[-97.1387,50.919146],[-97.138692,50.919018],[-97.138537,50.919022],[-97.138545,50.91915]]]},"properties":{}},
    {"type":"Feature","geometry":{"type":"Polygon","coordinates":[[[-97.106312,50.949822],[-97.106178,50.949845],[-97.106255,50.950025],[-97.106389,50.950002],[-97.106312,50.949822]]]},"properties":{}},
.
.
.
  ]
}

我正在阅读此文件并将其加载到ee.FeatureCollection()中：

import json

# Open file to parse
with open('/content/drive/My Drive/Earthengine/buildings.geojson') as f:
  data = json.load(f)

# Parse each of the polygons to features
polygons = []
for feat in data['features']:
  polygons.append(ee.Feature(feat))

# Create the feature collection
buildings = ee.FeatureCollection(polygons)

但是，当我尝试将这些建筑物展示为 folium 时：

polyImage = ee.Image(0).byte().paint(buildings, 1)
polyImage = polyImage.updateMask(polyImage)

mapid = polyImage.getMapId()
map = folium.Map(location=[38., -100.], zoom_start=5)
folium.TileLayer(
    tiles=EE_TILES.format(**mapid),
    attr='Google Earth Engine',
    overlay=True,
    name='training polygons',
  ).add_to(map)
map.add_child(folium.LayerControl())
map

我收到以下错误：

---------------------------------------------------------------------------
BrokenPipeError                           Traceback (most recent call last)
<ipython-input-7-3c769c73ff13> in <module>()
      2 polyImage = polyImage.updateMask(polyImage)
      3 
----> 4 mapid = polyImage.getMapId()
      5 map = folium.Map(location=[38., -100.], zoom_start=5)
      6 folium.TileLayer(

15 frames
/usr/lib/python3.6/ssl.py in write(self, data)
    640         The 'data' argument must support the buffer interface.
    641         """
--> 642         return self._sslobj.write(data)
    643 
    644     def getpeercert(self, binary_form=False):

BrokenPipeError: [Errno 32] Broken pipe

会不会因为文件太大而发生这种情况？ 有办法解决这个问题吗？

Answer 1

我很确定这正在发生，因为 Earth Engine 仍在计算，并且在未收到响应后连接在客户端关闭。 有关 Broken Pipe 的更多信息，请参阅此答案。

假设您有很多多边形，Earth Engine 必须构建多边形然后将它们栅格化，这可能不需要大量计算但可能需要一些时间，因此损坏的 pipe。 解决此问题的一种方法是将建筑物多边形保存为资产，然后将资产直接加载到 map。

您可以使用以下语法导出 featureCollection：

task = ee.batch.Export.table.toAsset(
  collection=buildings,
  description='my-buildings', 
  assetId='users/myusername/buildings'
)
task.start()