How to increase contrast of a 3d plot? Should I set colorbar to log scale?

Question

Xiaohan Du 2018-9-9

0
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https://ww2.mathworks.cn/matlabcentral/answers/418265-how-to-increase-contrast-of-a-3d-plot-should-i-set-colorbar-to-log-scale

回答： Akshay Khadse 2018-9-12

Hi all,

I have the following code to plot a structure with y-displacement as ColorMapData ('node.mat', 'elem.mat', 'phiOri.mat' are attached):

clear; clc;
load('node.mat', 'node');
load('elem.mat', 'elem');
load('phiOri.mat', 'phiOri')
dis = reshape(phiOri(:, 1), [3, 3146]);
dis = dis';
scaleFactor = 1;
pdeplot3D(node, elem, 'ColorMapData', abs(dis(:, 2)));
colormap jet
axis image

The image is like this:

As you can see the majority of displacement are small, thus most of the structure are blue. Is there a way to enhance the contrast, i.e. enhance the display of region [0 0.06], such that change in the colormap are clearer?

I think change colorbar to log scale may achieve what I want, but I don't know how to do this, please help! Thanks in advance!

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Answer 1

Akshay Khadse 2018-9-12

0
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https://ww2.mathworks.cn/matlabcentral/answers/418265-how-to-increase-contrast-of-a-3d-plot-should-i-set-colorbar-to-log-scale#answer_336460

在 MATLAB Online 中打开

Instead of modifying the colormap scale, you could take a log of the ColorMapData values to magnify your data variations.

I tried out the following snippet:

pdeplot3D(node, elem, 'ColorMapData', 10+log10(abs(dis(:, 2))));

Please refer to the documentation of the ' colormap ' function if you still need to modify the color scales. You can generate logarithmically spaced vectors by using ' logspace ' and then construct colormap matrices using those.