function p = h3d_params
	% function p = h3d_parameters
	%
	% Returns a struct containing all the parameters used by the code.
	p = struct;
	
	p = add(p, 'max_norm',                      8, 'Maximum norm for input points (m).');
	p = add(p, 'rho_cell_size',               0.03, 'Size of a rho cell when computing the spectrum. (m)');
	p = add(p, 'angular_cell_size_deg',         3, 'Approximate angular resolution of the HS.');

	p = add(p, 'upsample',                      1, 'Upsampling factor for the HS to pass to interp2(). No upsampling = 0, double = 1, etc.');
	
	p = add(p, 'guess_rot_max_peaks1',          2, 'Number of peaks in HS1 to consider while guessing rotations.' );
	p = add(p, 'guess_rot_max_peaks2',          6, 'Number of peaks in HS2 to consider while guessing rotations.' );
	p = add(p, 'guess_rot_first_corr_num_hyp', 3, 'How many different hypotheses to consider for the first correlation of 360 deg. Note spectrum is 180deg-periodic, so it makes sense to have at least 2.');
	p = add(p, 'guess_rot_max_correction_deg',  6, 'Max angular correction after the first (first is 360deg)');
	p = add(p, 'guess_rot_num_compensations',   4, 'Number of local compensations, after the big one');
	p = add(p, 'guess_rot_merge_hyp_threshold_deg', 5, 'Threshold under which two rotations hypotheses are merged into one.');
	
	p = add(p, 'cyl_amplitude_deg',           150, 'Fascia intorno equatore' );
	p = add(p, 'cyl_num_alpha_steps',          15, 'Number of alpha steps in the cylinder');
	p = add(p, 'cyl_num_beta_steps',          256, 'Number of beta steps in the cylinder');
	

	p = add(p, 'guess_tran_max_directions',     8, 'Number of directions to use');
	p = add(p, 'guess_tran_max_num_hyp',        4, 'Maximum number of hypotheses per direction');
	p = add(p, 'guess_tran_two_birds_one_stone',1, 'Use when doing HT with normals');
	
	p = add(p, 'hausdorff_num_points', 200, 'Number of points to use for Hausdorff distance');
	p = add(p, 'hausdorff_plausible_threshold', 0.3, 'Plausibility threshold for Hausdorff');
	

	p = add(p, 'debug_true_R',                  0, 'True rotation (for debugging purposes)');
	p = add(p, 'debug_true_T',                  0, 'True translation (for debugging purposes)');
	p = add(p, 'debug_compensation_show',       1, 'Show figures while doing rotation compensation');
	p = add(p, 'debug_show_translation',        0, 'Show the correlations for the translation (note this crashes Matlab for many figures are generated)');
	
function p = add(p, name, default, desc)

	if not(isfield(p,'system'))
		p.system = struct;
		p.system.defaults = struct;
		p.system.descriptions = struct;
		p.system.order = {};
	end
	
	if isfield(p, name)
		error(sprintf('Already have a parameters "%s"\n', name));
	end
	
	p.(name) = default;
	p.system.defaults.(name) = default;
	p.system.descriptions.(name) = desc;

	n = numel(p.system.order);
	p.system.order{n+1} = name;