Use color as fourth dimension on a surf or mesh plot?

Question

Megan LaMonica 2023-1-11

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https://ww2.mathworks.cn/matlabcentral/answers/1891780-use-color-as-fourth-dimension-on-a-surf-or-mesh-plot

回答： Cris LaPierre 2023-1-11

Hello,

I have data with four dimensions. I have plotted 3 of the 4 dimensions successfully as a mesh and surf plot. Now, I would like color to represent the fourth dimension (i.e.: not corresponding to the Z value, but separate from it).

I tried to implement color as follows:

surf(X,Y,vq,ind2rgb(data,parula))

where 'data' is my n x m x p matrix of the fourth dimension values I want plotted. However, the documentation suggests that I need an m x n or n x m x 3 matrix instead. What can I do to visualize my fourth dimension as color? Would I need to use slices, or could I somehow reshape the data to work?

Currently, I get the following error:

Index in position 1 is invalid. Array indices must be positive integers or logical values.

Error in matlab.images.internal.ind2rgb (line 24)

rgb(1:height, 1:width, 1) = reshape(cm(indexedImage, 1), [height width]);

Error in ind2rgb (line 17)

r = matlab.images.internal.ind2rgb(a, cm);

Any help would be much appreciated! Thank you for your time.

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Answer 1

Cris LaPierre 2023-1-11

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https://ww2.mathworks.cn/matlabcentral/answers/1891780-use-color-as-fourth-dimension-on-a-surf-or-mesh-plot#answer_1145960

在 MATLAB Online 中打开

I'm not exactly sure what if this is the answer is helpful, as the solution may be dependent on your specfic data. Consider saving your variables to a mat file and attaching it to your post.

Here's an example that creates a surf using sin and cos, but colors it using the RGB data from peppers.png

[img,cmap] = imread('peppers.png');

x=1:size(img,2);

y=1:size(img,1);

[X,Y] = meshgrid(x,y);

Z = sind(X) + cosd(Y);

surf(X,Y,Z,img,'EdgeColor','none')