How can I apply variable transparency to a plot using scatter3?

I'm producing a 3D model, and interior points happen to be more interesting to me. I have a 4-column matrix representing (x,y,z,intensity), and I'm most interested in the high-intensity points; currently they're coloured by intensity. Can I make it so that the transparency of low-intensity points is increased (but I need them to still be visible)?

Thanks

[Steffen Adria]

I have found a solution! I scaled both the colour and *size* of my points so that the outer, less intense points are smaller than the inner, more intense points I want to see, so I can see past the outer layer!

[raym]

Great! I also have same problem

Answer 1

[Patrick Kalita]

MATLAB doesn't allow you to control the transparency of markers.

If you don't have a tremendous number of data points you could try drawing small spherical surfaces at each data point. Then you could control the transparency of those surfaces. Here's a File Exchange submission that might help you get started.

[Steffen Adria]

That's what I was afraid of. Thank you. I do have a tremendous number of points, I plot as many as my computer will do.

[Walter Roberson]

Markers are not used for scatter3() or surf(). scatter3() will draw small spheres for the points, as patches, and it is possible to control the transparency of those patches.

[Ehsan Asadi]

If scatter3 uses patches, then how we can add transparency?

[raym]

scatter3 uses patches? How to do it?

[Walter Roberson]

In R2014a and earlier, scatter3() uses patches. In R2014b and later, it does not.

In R2014b and later, there is MarkerFaceAlpha property that can be used to set a single transparency for all of the points.

In R2014b and later, to adjust each of the transparencies individually, then if h is the handle returned by calling scatter3(),

N = h.MarkerHandle.FaceColorData;
N(4,:) = new transparency data, expressed as integer values from 0 to 255
h.MarkerHandle.FaceColorData = N;

[Jacek Wodecki]

it doesn't work, matlab 2021b

EDIT: still doesn't work until 2024a

Answer 2

[Lockenlui]

You can use

h = scatter3(..)
alpha = 0.5;
set(h, 'MarkerEdgeAlpha', alpha, 'MarkerFaceAlpha', alpha)

in order to set the transparancy for the edge as well as the face of the marker.

[Jacek Wodecki]

it doesn't work, matlab 2021b

[s yuan]

It does work, matlab 2023b

Answer 3

[bym]

I am not sure I understand the question, perhaps

slice()

would be useful?

[Steffen Adria]

I need to see the whole thing at once in 3D. I need to see the exterior most of all, but I'm also trying to see some points that might be lying just inside the surface. It's fuzzy data so some noise is present and I'm not sure where the boundary between empty space and the object is. I'm expecting that an intense core will be present under a thin layer of low-intensity points; I want to be able to see both.

[KRUNAL]

Were you able to find a solution to the above question Steffen. If so, can you please post your code here