New diffraction functions and tests for UTD method

applications/SoundFieldSimulation/Diffraction/ita_diffraction_utd_illumination_fadeout.m

+function [ f ] = ita_diffraction_utd_illumination_fadeout( wedge, source_pos, receiver_pos, reflection_at_main_face )
+%ita_diffraction_utd_illumination_fadeout Returns a scalar factor to fade out 
+%last diffraction component between shadow and half way towards reflection boundary
+
+assert( ~ita_diffraction_shadow_zone( wedge, source_pos, receiver_pos ) )
+assert( ~ita_diffraction_reflection_zone( wedge, source_pos, receiver_pos, reflection_at_main_face ) )
+assert( ita_diffraction_utd_illumination_sign( wedge, source_pos, receiver_pos, reflection_at_main_face ) == -1 )
+
+if reflection_at_main_face
+    vw = wedge.main_face_normal;
+else
+    vw = wedge.opposite_face_normal;
+end
+
+vs = source_pos - wedge.location;
+vr = receiver_pos - wedge.location;
+distance_plane2source = dot( vs / norm( vs ) , vw / norm( vw ) );
+distance_plane2receiver = dot( vr / norm( vr ) , vw / norm( vw ) );
+s = 1 - abs( distance_plane2source / distance_plane2receiver ); % 0 ... 1
+f = cos( s *  pi / 2 ) * cos( s *  pi / 2 ); % cosine-square fading from 1 to 0
+
+end

applications/SoundFieldSimulation/Diffraction/ita_diffraction_utd_illumination_sign.m

+function [ diffr_comp_sign ] = ita_diffraction_utd_illumination_sign( wedge, source_pos, receiver_pos, reflection_at_main_face )
+%ITA_DIFFRACTION_UTD_ILLUMINATION_SIGN Returns -1 if source is closer to
+%shadow boundary and 1 if source is closer to reflection boundary 
+
+assert( ~ita_diffraction_shadow_zone( wedge, source_pos, receiver_pos ) )
+assert( ~ita_diffraction_reflection_zone( wedge, source_pos, receiver_pos, reflection_at_main_face ) )
+
+if reflection_at_main_face
+    vw = wedge.main_face_normal;
+else
+    vw = wedge.opposite_face_normal;
+end
+
+vs = source_pos - wedge.location;
+distance_plane2source = dot( vs / norm( vs ) , vw / norm( vw ) );
+if distance_plane2source > 0
+    diffr_comp_sign = 1; % closer to reflection boundary
+else
+    diffr_comp_sign = -1; % closer to shadow boundary
+end
+
+end

applications/SoundFieldSimulation/Diffraction/plots/ita_diffraction_plot_utd_total_field_stienen_diss.m

+%% Total sound field of a difraction problem at a rectagular wedge using UTD
+
+% Author: Jonas Stienen
+
+
+%% Scene
+
+n1  = [ -1  1  0 ] / sqrt( 2 ); % main face
+n2  = [ +1  1  0 ] / sqrt( 2 );
+loc = [  0  0  0 ];
+w = itaInfiniteWedge( n1, n2, loc );
+
+s   = 5 * [ -1   0  0 ];
+s_1 = 5 * [  0  -1  0 ]; % image source n1
+r1  = 5 * [ -1  +1  0 ] / sqrt( 2 );
+
+a = w.apex_point( s, r1 );
+ad = w.edge_direction;
+c = 344; % speed of sound
+
+f = [ 20, 50, 100, 200, 400, 800, 1600, 3200, 6400, 12800, 24000 ]';
+f_legend = { '20 Hz', '50 Hz', '100 Hz', '200 Hz', '400 Hz', '800 Hz', ...
+    '1.6 kHz', '3.2 kHz', '6.4 kHz', '12.8 kHz', '24 kHz' };
+
+num_angles = 1000;
+alpha_d_start = w.opening_angle;
+alpha_d_end = 0;
+alpha_d = linspace( alpha_d_start, alpha_d_end, num_angles );
+
+% Set different receiver positions rotated around the aperture
+R = norm( r1 ) * [ cos( alpha_d - pi/4 ); sin( alpha_d - pi/4 ); zeros( 1, numel( alpha_d ) ) ]';
+
+% wavenumber
+k = 2 * pi * f ./ c;
+
+% store results in ita audio format
+res_data_template = itaResult();
+res_data_template.resultType = 'signal';
+res_data_template.freqVector = f;
+
+
+%% Sound field simulation
+
+N = size( R, 1 );
+for n = 1 : N
+    
+    r = R( n, 1:3 );
+    
+    r_dir = norm( r - s );
+    H_i = 1 ./ r_dir .* exp( -1i .* k .* r_dir ); % direct sound component
+    
+    r_1_dir = norm( r - s_1 );
+    H_r = 1 ./ r_1_dir .* exp( -1i .* k .* r_1_dir ); % reflected sound component
+
+    H_d = ita_diffraction_utd( w, s, r, f, c ); % diffracted sound component
+    
+    H = H_d; % Total sound field ... diffracted component always present
+    if ~ita_diffraction_shadow_zone( w, s, r )
+        H = H + H_i;
+    end
+    if ita_diffraction_reflection_zone( w, s, r, true ) % main face reflection
+        H = H + H_r;
+    end
+    
+    att_sum = res_data_template;
+    att_sum.freqData = H ./ H_i; % Insertion loss
+        
+    if n == 1
+        att_sum_all = att_sum;
+    else
+        att_sum_all = ita_merge( att_sum_all, att_sum );
+    end
+    
+end
+
+
+%% Plot
+
+fg = figure( 'units', 'normalized', 'outerposition', [0 0 1 1], 'visible', 'on' );
+
+angles = rad2deg( linspace( alpha_d( end ), alpha_d( 1 ), numel( alpha_d ) ) ); % Reverse angle on axis
+h = plot( angles, flip( att_sum_all.freqData_dB', 2 ) );
+
+title( 'Transfer function nomalized to free-field transmission' )
+xlabel( 'alpha_d / degree' )
+ylabel( 'dB' )
+
+lgd = legend( flip( f_legend ), 'Location', 'southwest' );
+lgd.NumColumns = 3;
+
+xlim( [ -5 275 ] );
+ylim( [ -35 10 ] );
+grid on;
+
+lw = linspace( 0.5, 2.5, numel( f ));
+for i=1:numel( f )
+    h( i ).LineWidth = lw( i );
+end
+
+
+%% Export
+
+set( fg, 'papersize', [ 16*2 9*2 ], 'units', 'centimeters' )
+print( 'ita_diffraction_plot_utd_total_field_stienen_diss', '-fillpage', '-dpdf' )

applications/SoundFieldSimulation/Diffraction/plots/ita_diffraction_plot_utd_total_field_stienen_diss_w_ground.m

+%% Total sound field of a difraction problem at a rectagular wedge using UTD
+
+% Author: Jonas Stienen
+
+
+%% Scene
+
+n1  = [ 0  1  0 ]; % main face 1
+n2  = [ 1  0  0 ]; % opposite face 2 / facade
+n3  = [ 0  1  0 ]; % ground plane / face 3
+loc = [  0  0  0 ];
+w = itaInfiniteWedge( n1, n2, loc );
+
+r    = [  2  -2  0 ];
+r2   = [ -2  -2  0 ]; % image receiver 2
+r3   = [  2  -4  0 ]; % image receiver 3
+r23  = [ -2  -4  0 ]; % image receiver 23 /  32
+s1  = 5 * [ 0  -1  0 ];
+
+a = w.apex_point( s1, r );
+ad = w.edge_direction;
+c = 344; % speed of sound
+
+f = [ 20, 50, 100, 200, 400, 800, 1600, 3200, 6400, 12800, 24000 ]';
+f_legend = { '20 Hz', '50 Hz', '100 Hz', '200 Hz', '400 Hz', '800 Hz', ...
+    '1.6 kHz', '3.2 kHz', '6.4 kHz', '12.8 kHz', '24 kHz' };
+
+%f = [ 20, 50, 100, 200, 400 ]';
+%f_legend = { '20 Hz', '50 Hz', '100 Hz', '200 Hz', '400 Hz' };
+
+num_angles = 1000;
+alpha_d_start = 0;
+alpha_d_end = pi;
+alpha_d = linspace( alpha_d_start, alpha_d_end, num_angles );
+
+% Set different receiver positions rotated around the aperture
+S = norm( s1 ) * [ - cos( alpha_d ); sin( alpha_d ); zeros( 1, numel( alpha_d ) ) ]';
+
+% wavenumber
+k = 2 * pi * f ./ c;
+
+% store results in ita audio format
+res_data_template = itaResult();
+res_data_template.resultType = 'signal';
+res_data_template.freqVector = f;
+
+
+%% Sound field simulation
+
+N = size( S, 1 );
+for n = 1 : N
+    
+    s = S( n, 1:3 );
+    
+    % Zero order
+    
+    r_dir = norm( s - r );
+    H_i = 1 ./ r_dir .* exp( -1i .* k .* r_dir ); % direct sound component
+    
+    r_1_dir = norm( s - r2 );
+    H_r = 1 ./ r_1_dir .* exp( -1i .* k .* r_1_dir ); % reflected sound component
+
+    H_d = ita_diffraction_utd( w, s, r, f, c ); % diffracted sound component
+    
+    % Ground reflection image
+    
+    r_dir_1 = norm( s - r3 );
+    H_i_1 = 1 ./ r_dir_1 .* exp( -1i .* k .* r_dir_1 ); % direct sound component
+    
+    r_1_dir_1 = norm( s - r23 );
+    H_r_1 = 1 ./ r_1_dir_1 .* exp( -1i .* k .* r_1_dir_1 ); % reflected sound component
+
+    [ H_d_1 , D_half ] = ita_diffraction_utd( w, s, r3, f, c ); % diffracted sound component
+    
+    % zero and first order components
+    
+    H = H_d; % Total sound field ... diffracted component always present
+    if ~ita_diffraction_shadow_zone( w, s, r )
+       H = H + H_i;
+    end
+    if ita_diffraction_reflection_zone( w, s, r, false ) % opposite face reflection
+        H = H + H_r;
+    end
+    
+    H_1 = H_d_1;
+    if ~ita_diffraction_shadow_zone( w, s, r3 )
+        H_1 = H_1 + H_i_1;
+    end
+    if ita_diffraction_reflection_zone( w, s, r3, false ) % opposite face reflection
+        H_1 = H_1 + H_r_1;
+    end
+    
+    H_1_half = zeros( numel( H_d_1 ), 1 );
+    if ita_diffraction_shadow_zone( w, s, r3 )
+        H_1_half = H_d_1; % Shadow zone yes diffraction only
+    else
+        H_1_half = H_i_1; % Direct sound yes
+        if ~ita_diffraction_reflection_zone( w, s, r3, false )
+            if ita_diffraction_utd_illumination_sign( w, s, r3, false ) == -1
+                sf = ita_diffraction_utd_illumination_fadeout( w, s, r3, false );
+                H_1_half = H_1_half + sf .* H_d_1; % closer to shadow zone diffraction yes
+            end
+        else
+            humbug = 1;
+        end
+    end
+    
+    att_sum = res_data_template;
+    att_sum.freqData = ( H ) ./ H_i; % Insertion loss
+        
+    if n == 1
+        att_sum_all = att_sum;
+    else
+        att_sum_all = ita_merge( att_sum_all, att_sum );
+    end
+    
+end
+
+
+%% Plot
+
+fg = figure( 'units', 'normalized', 'outerposition', [0 0 1 1], 'visible', 'on' );
+
+h = plot( rad2deg( alpha_d ), flip( att_sum_all.freqData_dB', 2 ) );
+
+title( 'Transfer function nomalized to free-field transmission' )
+xlabel( 'alpha_d / degree' )
+ylabel( 'dB' )
+
+lgd = legend( flip( f_legend ), 'Location', 'southwest' );
+lgd.NumColumns = 3;
+
+xlim( [ -5 185 ] );
+ylim( [ -35 10 ] );
+grid on;
+
+lw = linspace( 0.5, 2.5, numel( f ));
+for i=1:numel( f )
+    h( i ).LineWidth = lw( i );
+end
+
+
+%% Export
+
+set( fg, 'papersize', [ 16*1.5 9*1.5 ], 'units', 'centimeters' )
+print( 'ita_diffraction_plot_utd_total_field_stienen_diss_with_ground', '-fillpage', '-dpdf' )