This KNIME workflow demonstrates how to measure built-up density in Massachusetts using Google Earth Engine (GEE) data and a chunk loop to avoid GEE API request payload size limits. The workflow processes US TIGER MAP data for Massachusetts census tracts and ESA WorldCover100 data to count values in a single band, providing a detailed analysis of built-up areas.
File Reader : Reads the shapefile containing Massachusetts census tract data from the US TIGER MAP.
Column Filter : Filters the necessary columns from the input data for further processing.
Chunk Loop Start : Initiates a loop to process data in chunks, preventing the GEE API error due to request payload size limits (10MB).
GeoDataFrame to Feature Collection:Converts the filtered GeoDataFrame to a Google Earth Engine Feature Collection, preparing it for GEE operations.
GEE Collection Image Reader :Reads the ESA WorldCover100 data (10M resolution) from GEE, focusing on the required geographical area.
GEE Count Values in Single Band:Counts the values in a specified single band of the ESA WorldCover100 data within the defined census tracts.
Feature Collection to Table :Converts the GEE Feature Collection with counted values back to a KNIME table format for further analysis.
Loop End : Concludes the chunk loop, aggregating the results from each chunk into a single output table.
Joiner: Joins the results from the GEE operations with additional geospatial data for comprehensive analysis.
Projection : Reprojects the geospatial data to the desired coordinate reference system (CRS) for consistency in analysis.
Area : Calculates the area of each census tract in the reprojected data, aiding in density calculations.
Math Formula : Applies mathematical formulas to compute built-up density using the area and count values.
Geospatial View : Provides a visual representation of the geospatial data, allowing for inspection and validation of the results.
Timer Info : Records the time taken for the entire workflow, providing insights into processing efficiency.
Created By:
Lingbo Liu
lingboliu@fas.harvard.edu
Spatial Data Lab project
Center for Geographic Analysis
Harvard University
File Reader : Reads the shapefile containing Massachusetts census tract data from the US TIGER MAP.
Column Filter : Filters the necessary columns from the input data for further processing.
Chunk Loop Start : Initiates a loop to process data in chunks, preventing the GEE API error due to request payload size limits (10MB).
GeoDataFrame to Feature Collection:Converts the filtered GeoDataFrame to a Google Earth Engine Feature Collection, preparing it for GEE operations.
GEE Collection Image Reader :Reads the ESA WorldCover100 data (10M resolution) from GEE, focusing on the required geographical area.
GEE Count Values in Single Band:Counts the values in a specified single band of the ESA WorldCover100 data within the defined census tracts.
Feature Collection to Table :Converts the GEE Feature Collection with counted values back to a KNIME table format for further analysis.
Loop End : Concludes the chunk loop, aggregating the results from each chunk into a single output table.
Joiner: Joins the results from the GEE operations with additional geospatial data for comprehensive analysis.
Projection : Reprojects the geospatial data to the desired coordinate reference system (CRS) for consistency in analysis.
Area : Calculates the area of each census tract in the reprojected data, aiding in density calculations.
Math Formula : Applies mathematical formulas to compute built-up density using the area and count values.
Geospatial View : Provides a visual representation of the geospatial data, allowing for inspection and validation of the results.
Timer Info : Records the time taken for the entire workflow, providing insights into processing efficiency.
Created By:
Lingbo Liu
lingboliu@fas.harvard.edu
Spatial Data Lab project
Center for Geographic Analysis
Harvard University