module NSWTopo::DEM
Public Instance Methods
blur_dem(dem_path, blur_path)
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# File lib/nswtopo/gis/dem.rb, line 41 def blur_dem(dem_path, blur_path) sigma = @smooth * @map.scale / 1000.0 half = (3 * sigma / @resolution).ceil coeffs = (-half..half).map do |n| n * @resolution / sigma end.map do |x| Math::exp(-x**2) end vrt = OS.gdalbuildvrt "/vsistdout/", dem_path xml = REXML::Document.new vrt xml.elements.each("//ComplexSource") do |complex_source| kernel_filtered_source = complex_source.parent.add_element("KernelFilteredSource") complex_source.elements.each("SourceFilename|OpenOptions|SourceBand|SourceProperties|SrcRect|DstRect") do |element| kernel_filtered_source.add_element element end kernel = kernel_filtered_source.add_element("Kernel", "normalized" => 1) kernel.add_element("Size").text = coeffs.size kernel.add_element("Coefs").text = coeffs.join ?\s complex_source.parent.delete complex_source end log_update "%s: smoothing DEM raster" % @name OS.gdal_translate "/vsistdin/", blur_path do |stdin| stdin.write xml end end
get_dem(temp_dir, dem_path)
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# File lib/nswtopo/gis/dem.rb, line 5 def get_dem(temp_dir, dem_path) txt_path = temp_dir / "dem.txt" vrt_path = temp_dir / "dem.vrt" te = @map.bounds(margin: margin).transpose.flatten Dir.chdir(@source ? @source.parent : Pathname.pwd) do log_update "%s: examining DEM" % @name gdal_rasters @path do |index, total| log_update "%s: examining DEM file %i of %i" % [@name, index, total] end end.tap do |rasters| raise "no elevation data found at specified path" if rasters.none? log_update "%s: extracting DEM raster" % @name end.group_by do |path, info| Projection.new info.dig("coordinateSystem", "wkt") end.map.with_index do |(projection, rasters), index| raise "DEM data not in planar projection with metre units" unless projection.proj4.split(?\s).any?("+units=m") paths, resolutions = rasters.map do |path, info| [path, info["geoTransform"].values_at(1, 2).norm] end.sort_by(&:last).transpose txt_path.write paths.reverse.join(?\n) @resolution ||= resolutions.first indexed_dem_path = temp_dir / "dem.#{index}.tif" OS.gdalbuildvrt "-overwrite", "-input_file_list", txt_path, vrt_path OS.gdalwarp "-t_srs", @map.projection, "-te", *te, "-tr", @resolution, @resolution, "-r", "bilinear", vrt_path, indexed_dem_path indexed_dem_path end.tap do |dem_paths| txt_path.write dem_paths.join(?\n) OS.gdalbuildvrt "-overwrite", "-input_file_list", txt_path, vrt_path OS.gdal_translate vrt_path, dem_path end end