3D graphic plot

Hello guys, if I have a 3D graph what I can do to measure the high of the graphic. Here's the graphic that I mean..

Answer 1

[Arthur Roué]

You can look for the surface handle in the axis children.

% Get current axe handle
hAxe = gca;

% Look for surface handle
vb = isa(hAxe.Children, 'matlab.graphics.chart.primitive.Surface')
hSurface = hAxe.Children(vb)

% Get values in surface properties
hSurface.XData
hSurface.YData
hSurface.ZData

EDIT : I assumed there is only one surface in this plot

[agung pratama]

Thanks a lot, I get the data in matrix form, can I transform it into a 2D graph like this picture?. I'm a newbie in MATLAB

[Arthur Roué]

You're welcome ! I answered your original question, can you accept it and post another one for this new one.?

[Walter Roberson]

It is not clear how u/pixel relates to the XData, YData, or ZData coordinates. Is height/mm the ZData ? The graphic we are shown only apperas to have one surface, so it is not clear where the second output of the 2D plot would come from.

[agung pratama]

The second 2D plot just an example i see from another 3D graph measurement. I don,t know how to get mine become like the second 2D plot.

[Walter Roberson]

You have three independent variables (x y, z) and one dependent variable (color)

You appear to want an output plot with one independent variable and one dependent variable. How do you want to synthesize the one independent variable from the four variables, and how do you want to synthesize the dependent variable from the four?

[agung pratama]

Here is the surface graphic i have, how can i measure the high from several distance between the surface? It seem the highet peak is about more than 250

[Walter Roberson]

is the input an rgb image or is it a surface plot?

your x and y axes are not labeled so I don't know what is being plotted

[agung pratama]

The input is an RGB Image. Its an XZ plane, please can you show me how?

[Walter Roberson]

If all you have is a single rgb image then you cannot measure height in most cases. See for example https://thevortexrug.com/ which is flat rugs that appear to have significant depth.

[agung pratama]

So what i have to do if i want to measure the height of something using Image in Matlab?

[Walter Roberson]

You need a stereo image pair with calibrated cameras.

Or the image has to have a reference pattern built into it, in which case an exact measurement is likely not possible but a range might be possible.

A reference pattern could, for example, be an equal-spaced grid of vertical lines being projected parallel to the table, so that you could bracket the actual height by counting the number of lines that appear on the object.

[agung pratama]

Thank you, Mr Roberson. I'm measuring the deflection of a plate using the codded light pattern and moire interferometry method as a reference pattern. I'm also using a camera to take the image when applying a centralized load to the plate.

Do you have any suggestion to measure the surface's height of the plate after applying centralized load?

[Walter Roberson]

A sample image would help, along with any necessary key information (such as distance between fringes, and any information about the coding of the light pattern.)

[agung pratama]

I don't have the image yet, the Laboratorium that experiment takes place close because of Covid-19. I hope next week I will able to do it. But i assume maybe something like this picture

Here I attach the coding I use to create the fringe pattern, it's an analog and binary grating. I'm still not sure what is the better one

[Bruno Luong]

If you have a fringe image then the unit of z axis is radian (phase angle) The bottom image is unwrapping of the first, the height is

h = (max(phi(:))-min(phi(:)))*lambda/(4*pi)

phi is unwrapped angle image (bottom), lambda is the wavelength of what ever wave used to measure this interference pattern. Due to the noise, you have to filter the image data, or perhaps use histogram to compute (max(phi)-min(phi)) that least affected by the noise.

[agung pratama]

Thanks, Mr Luong. Can you give some example so I can understand how to use the equation you give.

[Bruno Luong]

Sorry I won't, since depends where you start at (type of image data, and you never explain us clearly what is it, your gave a color map, then a bananas, something about RGB, then a curve, then a fringe signal) and there might be many step more or less complex and requires some skill (for example compute the phase phi) to arrive at the heigh from the rawdata image of your fringes.

I gave you a general steps that must be carried out. If it's not clear, you should teach yourself or ask questions to your advisor, or whom ever gave you the task.

[agung pratama]

Thank you, Mr Luong, for your time and your attention. I'm a newbie in Matlab, perhaps I should learn more and more.