Uniform point interpolation along a line described by non-uniform distributed points

Hi everyone,

I would like to have uniformly distributed points along a line. The line in question is being described by non-uniform points. Does any of you know about any function to do so?

Thank you in advance for the help!

Álvaro

[dpb]

doc interp1

Answer 1

[Image Analyst]

See this demo:

% Code to plot data, plus points interpolated in between the data.
clc;    % Clear the command window.
clearvars;
close all;  % Close all figures (except those of imtool.)
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 22;

% Make up sample data.
numOriginalPoints = 20;
xOriginal = sort(100 * rand(1, numOriginalPoints), 'ascend');
yOriginal = 30 * rand(1, numOriginalPoints) - 10;
% Plot them
subplot(3, 1, 1);
plot(xOriginal, yOriginal, 'ro-', 'LineWidth', 2);
grid on;
xlabel('X', 'FontSize', fontSize);
ylabel('Y', 'FontSize', fontSize);
title('Training Points', 'FontSize', fontSize);

% Interpolate points in between, linearly from the min to the max.
numNewPoints = 100;
xInterpolated = linspace(min(xOriginal), max(xOriginal), numNewPoints);
yInterpolated = interp1(xOriginal, yOriginal, xInterpolated);
% Plot interpolated points.
subplot(3, 1, 2);
plot(xInterpolated, yInterpolated, 'bo-', 'LineWidth', 2);
% Plot training points over them so we can see where they are in relation to the new points.
hold on;
plot(xOriginal, yOriginal, 'ro', 'LineWidth', 2);
grid on;
title('Interpolated Points without Including Training Points', 'FontSize', fontSize);
xlabel('X', 'FontSize', fontSize);
ylabel('Y', 'FontSize', fontSize);
legend('Interpolated', 'Training');
% Enlarge figure to full screen.
set(gcf, 'Units', 'Normalized', 'OuterPosition', [0, 0.04, 1, 0.96]);

% Note, if you want the original points included in the set of new, interpolated points, 
% Add them to xInterpolated list.
subplot(3, 1, 3);
xInterpolated = sort([xInterpolated, xOriginal], 'ascend');
yInterpolated = interp1(xOriginal, yOriginal, xInterpolated);
% Plot interpolated points.
plot(xInterpolated, yInterpolated, 'bo-', 'LineWidth', 2);
% Plot training points over them so we can see where they are in relation to the new points.
hold on;
plot(xOriginal, yOriginal, 'ro', 'LineWidth', 2);
grid on;
xlabel('X', 'FontSize', fontSize);
ylabel('Y', 'FontSize', fontSize);
title('Interpolated Points Including Training Points', 'FontSize', fontSize);
legend('Interpolated', 'Training');
% Enlarge figure to full screen.
set(gcf, 'Units', 'Normalized', 'OuterPosition', [0, 0.04, 1, 0.96]);

[Álvaro Pardo]

Thanks for the answer and sorry for my late reply. I've tried the code and seems to work. However, I would like to take into account the direction between each pair of original points to calculate later the interpolated ones based on that direction. Any ideas?