How to find when a surface deviates from other surface(s)

Hi guys,

I have 3 surfaces. I want to find out values for x and y, where each of the three surfaces deviates from the other two by more than 0.5 value on the z axis. Is this a simple enough thing?

I can imagine it being super easy to do with only two surfaces because you could just substract one from the other. But how do I do it with 3 surfaces? Any ideas?

Thanks

Answer 1

[Walter Roberson]

OfInterest = any(diff( sort( cat(3, surface1Z, surface2Z, surface3Z), 3), 3) > 0.5, 3);

This will be a logical array.

[A]

Thanks so much! I will try this tonight.

Just curious, is there a way to graph this logical array so the 'deviation' can be graphically visualized?

Thank you!

[Walter Roberson]

image(ofInterest + 0)

or

image(ofInterest);
colormap(gray(2));

[A]

Hi Walter,

Thanks for your response. I have tried to test this out. Here's what I used:

>> x = [-10:10];
>> y = [-10:10];
>> test1 = x + 0.5*y;
>> test2 = x + y;
>> test3 = x + 1.5*y;
>> testI = meshgrid(test1);
>> testII = meshgrid(test2);
>> testIII = meshgrid(test3);
>> surf(x,y,testI);
>> hold on
>> surf(x,y,testII);
>> surf(x,y,testIII);
>> OfInterest = any(diff( sort( cat(3, test1, test2, test3), 3), 3) > 0.5, 3);
>> OfInterest

OfInterest =

    Columns 1 through 15

       0     0     0     0     0     0     0     0     1     1     0     0     0     0     0

    Columns 16 through 18

       0     0     0

>> image(OfInterest);
>> colormap(gray(2));

Just a couple of questions.

1) First of all, am I doing it right?

2) I am not sure how to read this/extrapolate the data that I need, which is the x and y value when z deviates by > 0.5 from either of the other two surfaces.

3) When I plot this using the image/colormap function at the end. I get the attached picture? Again, not sure how to read this?

Thank you