Error with interp3 - please help

I am trying to use interp3 on scatter data, and I'm getting the error:

Error using griddedInterpolant
The grid vectors are not strictly monotonic increasing.

Command:

[x,y,z] = meshgrid(0:0.25:1,0:0.25:1,0:0.25:2);

I3D=interp3(scatter(:,1),scatter(:,2),scatter(:,3),scatter(:,4),x,y,z,'linear');

Any idea what the issue is? I've done the same thing with 2D data using 'griddata', not sure why MATLAB is angry.

Thanks in advance!

Answer 1

[Walter Roberson]

Your scatter(:,1), scatter(:,2), scatter(:,3) each need to be in monotonic increasing order.

If you are attempting to interpolate a scattered set of values to a grid, you need to use one of the scattered interpolant routines, not a gridded interpolant line interp3()

Answer 2

[J M]

Sigh. Indeed. Thank you both.

F=scatteredInterpolant(scatter(:,1),scatter(:,,2),scatter(:,,3),scatter(:,,4));
I=F(a1,a2,a3);

Best way to plot values for 3 spatial dimensions?

[Walter Roberson]

http://uk.mathworks.com/matlabcentral/answers/246796-matlab-4d-color-plot#answer_194704

http://uk.mathworks.com/matlabcentral/answers/214805-how-to-plot-3d-surf-or-plot3#answer_177680