Create 3D Surface

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Kostas Chatz
Kostas Chatz 2012-2-13
编辑： Cedric 2013-10-10
Hello,
I'm trying to create a 3D surface for simulation purposes. My code is:
function ZZ = plot_surface_test(Xl, width)
grid_points=6;
for i=1:grid_points*11
xx(i)=i/(grid_points*10);
for j=1:grid_points*11;
C(i,j)=0;
yy(j)=j/(grid_points*10);
ii=min(find((xx(i)-Xl(1,:)).^2+(yy(j)-Xl(2,:)).^2==min((xx(i)-Xl(1,:)).^2+(yy(j)-Xl(2,:)).^2)));
ZZ(i,j)=Xl(3,ii)*exp(-width(ii)*((xx(i)-Xl(1,ii)).^2+(yy(j)-Xl(2,ii)).^2));
end
end
surf(ZZ)
I would like some suggestions please according to what matrixes Xl and width should be so that this code generate a real-like surface.
Thank you

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回答（2 个）

Walter Roberson
Walter Roberson 2012-2-13
You are going to be done in by floating point error. http://matlab.wikia.com/wiki/FAQ#Why_is_0.3_-_0.2_-_0.1_.28or_similar.29_not_equal_to_zero.3F
Also, min(find(X)) can be replaced by find(X,1)
Kevin Holst
Kevin Holst 2012-2-13
It appears that Xl should be a 3x66 numeric matrix and width should be a 1x66. Xl(1,:) looks like it contains an x coordinate for a measurement, Xl(2,:) looks to contain the y coordinate, and Xl(3,:) contains the measurement. I'm not sure about width. It also lookes like you can get rid of C(i,j)=0; unless that's used somewhere later for something.
What else do you need to know about this?
  2 个评论
Kostas Chatz
Kostas Chatz 2012-2-13
I've tried numeric matrixes and the result is not a a real-like surface
Specificly i've put for Xl:
for i=1:grid_points;
for j=1:grid_points;
Xl(1,(i-1)*grid_points+j)=i/grid_points;
Xl(2,(i-1)*grid_points+j)=j/grid_points;
Xl(3,(i-1)*grid_points+j)=maximum_height_surface*rand;
end
end
but i don't have any idea for width.
I've tried an integer instead of vector width and the only thing i get is some random peaks that are not connected to each other.
Kevin Holst
Kevin Holst 2012-2-14
I just put in width = ones(1,66) and it worked for me. It produces a surface that has small curved square plateaus in a 6x6 square. Unfortunately, I'm not in a place where I can upload at screenshot. What are you expecting the surface to look like?

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