Especificar valores de una matriz dentro de un poligono

Buenas tardes.

Teniendo una matriz de 256x256 enteramente con valores 0.5.

Me gustaría ponerle un valor concreto (por ejemplo 0.8) a los valores de la matriz que estén dentro de una forma geometrica delimitada por unas coordenadas x e y.

Lo he intentado con regionfill pero no soy capaz.

Muchas gracias y quedo a vuestra disposción.

Answer 1

[Keshav]

To set specific values within a geometric shape in a matrix, you can use 'poly2mask' function. The 'poly2mask' function sets pixels that are inside the polygon to 1 and sets pixels outside the polygon to 0. Afterwards, you can utilize the logical indexing to assign the specific value in the matrix.

Below is a sample code for reference:

% Create a 256x256 matrix filled with 0.5 values
matrix = ones(256,256) * 0.5;

% Change the x and y coordinate according to your requirement.
x = [1, 10, 1, 10];
y = [5, 5, 15, 15];

% Create a logical mask for the shape
mask = poly2mask(x, y, 256, 256);

% Set the desired value (e.g., 0.8) within the shape
matrix(mask) = 0.8;

You can read more about 'poly2max' function in the below MathWorks documentation.

https://in.mathworks.com/help/images/ref/poly2mask.html