Last time we calculated the biomass in Shanxi Province, but a new problem appeared. The problem is that there are many feature collections composed of features, about 8,000, which makes it impossible to carry out the next calculation and directly exceeds the quota. .
method 1:
When we face this problem, there are two solutions, one is to fuse these faces in ArcGIS, and fuse them into one face, so that it becomes a huge featurecollection that fuses many different faces
Method 2: We can apply a function in GEE:
union(maxError)
Merges all geometries in a given collection into one and returns a collection containing a single feature with only an ID of 'union_result' and a geometry.
Combines all geometries in the given collection into a single collection and returns a collection containing only a single feature with ID 'union_result' and a single geometry.
Arguments:
this:collection (FeatureCollection):
The collection being merged.
maxError (ErrorMargin, default: null):
The maximum error allowed when performing any necessary reprojections. If not specified, defaults to the error margin requested from the output.
Returns: FeatureCollection
Code:
//这是原始的众多矢量图
var shanxi = ee.FeatureCollection('projects/ee-shiyan/assets/WXrh').geometry();
print("shanxi",shanxi)
//这是合并后的矢量集合
var shanxi1 = ee.FeatureCollection('projects/ee-shiyan/assets/WXrh').union();
print("shanxi1",shanxi1)Vector result for the first one:
The second is the composite set
Of course, there are still too many vectors, which far exceeds the operation of GEE. Although it can be calculated, the time series analysis calculation of the series is still timed out. Therefore, it is recommended not to use more than 5000 small vectors for online operations.
