# How to find the error between two plots and plot the error in same diagram

20 views (last 30 days)
Abdul Sajeed Mohammed on 15 Feb 2022
Commented: Robert U on 24 Feb 2022
I need to plot error between two plots Ground_truth and Estimated_Long_Lat
Sharing my code here
figure;
Estimated_long = 180 / pi * lon;
Estimated_Lat = 180 / pi * lat;
plot(180 / pi * lon, 180 / pi * lat,'x','Linewidth',0.5);
hold on
G_Long = Ground_Truth(:,1);
G_Lat = Ground_Truth(:,2);
plot(G_Long,G_Lat,'-x','Linewidth',2)
hold on
hold off
ylabel('Latitude, [deg]','FontSize', 13);
xlabel('Longitude, [deg]','FontSize', 13);
title('Trajectory of vehicle with position close to Lane level','FontSize', 15)
legend('Estimated trajectory', 'Centre nodes of True trajectory','best')
Thanks
Abdul Sajeed Mohammed on 15 Feb 2022
yes, but problem is lat and long combined give me location. for 'n' number of lat _long positions with equal dimensions of ground truth lat_long points...how can i find distance or say difference between them. I am unable to proceed further.

Robert U on 15 Feb 2022
Hi Abdul Sajeed Mohammed,
here some example that is close to what you do:
% example data params (circular trajectory)
R = 1000;
phi = 0:360;
% uniformly distributed noise (signed)
noise = 100 .* (rand(1,length(phi)) - 0.5);
% generate example date
Estimated_long = R .* sind(phi) + noise;
Estimated_Lat = R .* cosd(phi) + circshift(noise,floor(length(phi)/2));
% generate ground truth data
Ground_Truth = R .* [sind(phi); cosd(phi)];
G_Long = Ground_Truth(1,:);
G_Lat = Ground_Truth(2,:);
% Choose whatever error norm is applicable
totalErr = sqrt((Estimated_Lat - G_Lat).^2 + (Estimated_long - G_Long).^2);
% create figure with two subplots
fh = figure;
fh.OuterPosition = fh.OuterPosition .* [0.5 0.5 2 2];
sh{1} = subplot(1,2,1,'Parent',fh);
sh{2} = subplot(1,2,2,'Parent',fh);
hold(sh{1},'on')
axis(sh{1},'equal')
% plot measured and ground truth data into first subplot
plot(sh{1},Estimated_long, Estimated_Lat,'x','Linewidth',0.5);
plot(sh{1},G_Long,G_Lat,'-x','Linewidth',2)
ylabel(sh{1},'x, [m]','FontSize', 13);
xlabel(sh{1},'y, [m]','FontSize', 13);
title(sh{1},'Trajectory of vehicle with position close to Lane level','FontSize', 15)
legend(sh{1},'Estimated trajectory', 'Centre nodes of True trajectory')
% plot total error in second subplot
plot(sh{2},phi,totalErr,'.','MarkerSize',12);
xlabel(sh{2},'phi, [deg]','FontSize', 13);
ylabel(sh{2},'total error, [m]','FontSize', 13);
title(sh{2},'Total error of vehicle','FontSize', 15)
Concerning error norms, have a look here:
Kind regards,
Robert
Robert U on 24 Feb 2022
It looks like there is a problem in the error plot. There are way too many curves unless you would have several runs. Can you post your measurement data as mat-file such that your code becomes executable?