How do I fit a surface to this data properly?

2 visualizaciones (últimos 30 días)
Pablo Fernandez el 16 de Sept. de 2021
Comentada: Pablo Fernandez el 19 de Sept. de 2021
Hi,
I have a set of datapoints (x,y,z) to which I want to fit a surface. I dont have a mathematical expression for the surface, so I tried to use the linear interpolation as in:
PTSGRID = 256;
xs = min(x):(max(x)-min(x))/(PTSGRID-1):max(x);
ys = min(y):(max(y)-min(y))/(PTSGRID-1):max(y);
[xq, yq] = meshgrid(xs,ys);
zq = griddata(x,y,z,xq,yq,'linear');
plot3(x,y,z,'mo')
hold on
mesh(xq,yq,zq);
However the fitted surface takes very strange values where there is no data defined, very different from what I would visually expect. Take a look for example at this figure, and the zone I circled:
How can I fit in a better way to avoid this behavior?
Thanks!
2 comentariosMostrar NingunoOcultar Ninguno
darova el 17 de Sept. de 2021
Attach the data
Pablo Fernandez el 17 de Sept. de 2021
Attached to the original post!

Iniciar sesión para comentar.

Respuestas (2)

KSSV el 16 de Sept. de 2021
3 comentariosMostrar 1 comentario más antiguoOcultar 1 comentario más antiguo
KSSV el 16 de Sept. de 2021
The same link has an example showing how to fit for a surface.
Pablo Fernandez el 16 de Sept. de 2021
Yes, I understand.
The specific point in my questions is how to get rid of the artifacts that appear when I try to interpolate the points in my dataset.

Iniciar sesión para comentar.

darova el 19 de Sept. de 2021
I don't have this problem
x = s.x;
y = s.y;
z = s.z;
xx = linspace(min(x),max(x),20);
yy = linspace(min(y),max(y),20);
[x1,y1] = meshgrid(xx,yy);
z1 = griddata(x,y,z,x1,y1);
Warning: Duplicate data points have been detected and removed - corresponding values have been averaged.
mesh(x1,y1,z1)
1 comentarioMostrar -1 comentarios más antiguosOcultar -1 comentarios más antiguos
Pablo Fernandez el 19 de Sept. de 2021
Hi, thanks for the answer.
You are not seing the effect in that plot because you are evaluating the interpolation in few points. The reason for the interpolation is to evaluate between the data lines. Try changing 20 for 256 in xx and yy definitions and you will notice the effect when plotting.
Regards

Iniciar sesión para comentar.

Categorías

Más información sobre Smoothing en Help Center y File Exchange.

R2020a

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by