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# frozen_string_literal: true require 'bundler/setup' require 'thor' require 'fileutils' require 'gdal/dataset' require 'gdal/raster_band' GDAL::Logger.logging_enabled = true module Examples class RemoveSmallPolygons < ::Thor desc 'filter SOURCE_PATH DEST_PATH SIZE', 'Removes polygons from SOURCE that are under SIZE' option :band_number, type: :numeric, default: 1 def filter(source_path, dest_path, size) puts "Copying source '#{source_path}' to '#{dest_path}'..." FileUtils.cp(source_path, dest_path) size = size.to_f dataset = GDAL::Dataset.open(dest_path, 'w') puts "Raster area: #{dataset.extent.area}" raster_band = dataset.raster_band(options[:band_number]) puts "Filtering polygons under size #{size}" raster_band.sieve_filter!(size, 4, progress_function: GDAL.simple_progress_formatter) shapefile_dir = "#{File.basename(dest_path, '.tif')}-shapefile" make_shapefile(shapefile_dir, dataset.spatial_reference.dup) do |layer| raster_band.polygonize(layer, pixel_value_field: 0) end puts "\nDone!" end private def make_shapefile(dir_path, srs) if File.exist?(dir_path) puts "Removing old shapefile: #{dir_path}" FileUtils.rm_rf(dir_path) end shp_driver = OGR::Driver.by_name 'ESRI Shapefile' data_source = shp_driver.create_data_source(dir_path) layer = data_source.create_layer('sieve-filtered', geometry_type: :wkbMultiPolygon, spatial_reference: srs) zone_num_field_def = OGR::FieldDefinition.new 'ZONE', :OFTInteger layer.create_field(zone_num_field_def) yield layer puts "feature count: #{layer.feature_count}" layer.each_feature.with_index do |feature, i| area = feature.geometry.area puts "Feature #{i} area: #{area}" end data_source.close end end end Examples::RemoveSmallPolygons.start(ARGV)
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9 entries across 9 versions & 1 rubygems