MATLAB Answers

x,y coordinates in .txt to points on image

1 view (last 30 days)
Hi there,
I need some help with loading coordinates in a .txt to points in an image. In the attached .txt are all the coordinates. What is the best approache to do this?
  1 Comment
Scott MacKenzie
Scott MacKenzie on 9 Jun 2021
What do you mean by "to points in an image"? The x-y coordinates are in the range -10 to +10 (approximately), so if you intend to map them to an image (e.g., 1000x2000), then some scaling will be necessary. Explain your objective, if you can, please.

Sign in to comment.

Accepted Answer

Adam Danz
Adam Danz on 10 Jun 2021
  1. Read in the file using A = readmatrix(filename)
  2. Plot the values using the plot command where x is the first column of A and y is the second column of A. Use indexing A(:,i)
  1 Comment
Image Analyst
Image Analyst on 10 Jun 2021
And make sure you scale the (x,y) values
[rows, columns, numColors] = size(yourImage);
x = rescale(A(:, 1), 1, columns);
y = rescale(A(:, 2), 1, rows); % Or however you need to do it.
and make sure you call
hold on;
after you call imshow() but before you call plot() or else the plot will blow away your image.
And remember images are indexed (row, column) which is (y, x) -- not (x,y) like plot() uses. So don't call yourImage(x, y) and expect that the gray level will match the gray level under that coordinate. You'd need to use yourImage(y, x).

Sign in to comment.

More Answers (0)






Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!