Unlike in various applications, where the gradient of a two dimensional matrix is calculated in x and y direction, the gradient of a digital elevation model (DEM) is usually returned as the steepest gradient. The steepest gradient is the largest downward slope of a pixel to one of its eight neighbors.
In this problem, your task will be to return the linear index of the steepest neighbor for each pixel in a gridded DEM. Pixels that don't have downward neighbors should receive the index value zero.
An example should help. The DEM is
dem = [1 5 9; ...
4 5 6; ...
8 7 3];
The result should be
IX = [0 1 4; ...
1 1 9; ...
2 9 0];
The results may not be unique, but the test cases have been built so that this is not a problem. The spatial resolution of the dem is dx=1 and dy=1. Note that the diagonal distance is hypot(dx,dy).
Solution Stats
Problem Comments
5 Comments
Solution Comments
Show comments
Loading...
Problem Recent Solvers69
Suggested Problems
-
Which values occur exactly three times?
5253 Solvers
-
Find the alphabetic word product
3475 Solvers
-
Sum of first n terms of a harmonic progression
521 Solvers
-
Change the sign of even index entries of the reversed vector
661 Solvers
-
Back to basics - mean of corner elements of a matrix
470 Solvers
More from this Author2
Problem Tags
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!
I'v developed the code using padarray and ordfilt2, which satisfies the test suite on my system, but seems like cody doesn't support padarray, is this so??
Hi Dishant, I thought the IPT is available, too, but apparently Cody does not support toolboxes at this time. see box on the right hand side: http://www.mathworks.de/matlabcentral/about/cody/
More difficult thant expected...
Pay attention. The problem is asking for the index and not the value of the steepest gradient. And gradients on diagonals directions must be divided by sqrt(2).
Test cases have been added and solutions have been rescored.