Problem with data triangulation

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LEONARDO BARNESCHI
LEONARDO BARNESCHI 2020-5-10
回答： darova 2020-5-10
Dear Matlab users,
I am trying to visualize a surface made of 3d scattered points. It is not an F(x,y) -> z function, z is just a scalar associated to (x,y) pairs. The x and y pairs form a fairly uniform rectangular grid on the xy plane. However, as soon as I try to use trisurf, the data are triangulated in an unexpected fashion.
I am actually interested in "connecting" these 3d points, not in an interpolation. The surface which can be glimpsed from scatter3 appears to be quite regular, but I wasn't succesfull in using trisurf or even surf.
Can you help me in achieving this goal? I am probably missing something in how the delaunay triangulation works.
Thank you in advance,
Leonardo

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采纳的回答

darova
darova 2020-5-10
It's because of different scales
try to scale your data
dx = max(x)-min(x);
y1 = (y-min(y))/(max(y)-min(y))*dx;
T = delaunay(x,y1);
trisurf(T, x, y, z)
axis vis3d

更多回答（1 个）

Ameer Hamza
Ameer Hamza 2020-5-10
编辑：Ameer Hamza 2020-5-10
If you want to visualize the data as surface, then you can first use griddata() to make it into a grid and then use surf()
x = [-108.743 -108.734 -108.71 -108.699 -108.684 -108.674 -108.664 -108.656 -108.651 -108.647 -108.645 -107.259 -107.216 -107.179 -107.148 -107.123 -107.123 -107.105 -107.104 -107.094 -107.093 -107.09 -105.784 -105.731 -105.683 -105.641 -105.605 -105.574 -105.55 -105.533 -105.523 -105.522 -105.519 -104.318 -104.255 -104.197 -104.144 -104.096 -104.054 -104.017 -103.986 -103.962 -103.944 -103.932 -102.862 -102.789 -102.721 -102.657 -102.598 -102.543 -102.494 -102.45 -102.412 -102.379 -102.353 -101.416 -101.334 -101.255 -101.18 -101.11 -101.044 -100.982 -100.925 -100.873 -100.826 -100.784 -99.981 -99.889 -99.8 -99.715 -99.633 -99.555 -99.481 -99.411 -99.346 -99.284 -99.228 -98.557 -98.455 -98.357 -98.261 -98.168 -98.078 -97.992 -97.909 -97.83 -97.755 -97.684 -97.144 -97.033 -96.924 -96.818 -96.715 -96.613 -96.515 -96.42 -96.327 -96.238 -96.152 -95.743 -95.623 -95.504 -95.388 -95.273 -95.161 -95.051 -94.943 -94.837 -94.733 -94.633 -94.353 -94.224 -94.096 -93.97 -93.845 -93.721 -93.599 -93.478 -93.359 -93.242 -93.127]
y = [0.034 -0.003 0.031 0.0 0.027 0.004 0.023 0.008 0.02 0.012 0.016 0.035 0.031 0.028 0.024 -0.003 0.02 0.016 0.001 0.013 0.005 0.009 0.036 0.032 0.028 0.025 0.021 0.017 0.013 0.01 -0.002 0.006 0.002 0.037 0.033 0.029 0.026 0.022 0.018 0.014 0.01 0.007 0.003 -0.001 0.037 0.034 0.03 0.026 0.023 0.019 0.015 0.011 0.007 0.003 -0.0 0.038 0.035 0.031 0.027 0.023 0.02 0.016 0.012 0.008 0.004 0.0 0.039 0.035 0.032 0.028 0.024 0.02 0.017 0.013 0.009 0.005 0.001 0.04 0.036 0.032 0.029 0.025 0.021 0.017 0.014 0.01 0.006 0.002 0.041 0.037 0.033 0.03 0.026 0.022 0.018 0.014 0.011 0.007 0.003 0.041 0.038 0.034 0.03 0.027 0.023 0.019 0.015 0.011 0.008 0.004 0.042 0.039 0.035 0.031 0.028 0.024 0.02 0.016 0.012 0.008 0.005]
z = [-868.98181753 -869.03656771 -869.00509484 -869.04789749 -869.02312937 -869.05456316 -869.03633374 -869.05691311 -869.04545933 -869.05571162 -869.0516303 -868.9851162 -869.00814308 -869.02572477 -869.03837956 -869.03783079 -869.04690268 -869.052603 -869.04921017 -869.05666944 -869.05589316 -869.05819117 -868.98833862 -869.01094443 -869.02795695 -869.04004859 -869.04791168 -869.05300034 -869.0571638 -869.05889077 -869.03849659 -869.05665363 -869.04993744 -868.99135258 -869.0134021 -869.02987311 -869.04137699 -869.04853356 -869.05287429 -869.05733 -869.05927447 -869.05702861 -869.05025941 -869.0387455 -868.99418691 -869.01558818 -869.0314407 -869.04237632 -869.04885431 -869.05217803 -869.05732872 -869.05940833 -869.05710197 -869.05022895 -869.03861199 -868.99666945 -869.01737986 -869.03274665 -869.04315341 -869.04910188 -869.05094408 -869.05733703 -869.05931497 -869.05685168 -869.04983308 -869.03810889 -868.99897704 -869.01895679 -869.03367205 -869.04362787 -869.04933318 -869.05243749 -869.05738309 -869.05890597 -869.05626901 -869.04905847 -869.03722417 -869.00101379 -869.02022918 -869.03437482 -869.04397026 -869.04968638 -869.05350931 -869.05745965 -869.05847175 -869.05539754 -869.04787576 -869.03585189 -869.00273423 -869.0211671 -869.03476459 -869.04409116 -869.04993815 -869.05406865 -869.05730611 -869.05770149 -869.05423116 -869.04651483 -869.03430857 -869.0041773 -869.0217949 -869.03486759 -869.04393834 -869.04990448 -869.05411243 -869.05676928 -869.05659592 -869.05271983 -869.04471149 -869.03232427 -869.00529229 -869.02209147 -869.03464015 -869.04350052 -869.04951656 -869.05362124 -869.05579053 -869.05509436 -869.05082327 -869.04252703 -869.02988852]
xg = linspace(min(x), max(x), 100);
yg = linspace(min(y), max(y), 100);
[Xg, Yg] = meshgrid(xg, yg);
Zg = griddata(x, y, z, Xg, Yg);
s = surf(Xg, Yg, Zg);
  1 个评论
LEONARDO BARNESCHI
LEONARDO BARNESCHI 2020-5-10
Dear Ameer,
the problem is that I should be able to just connect properly the 3d points. In a sense, they should be connected according to the distance on the xy plane. The surface or "trisurface" should be regular. I can get something like this using interpolation, but I was wondering if I could just work on the connectivity.
Thank you,
Leonardo

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