Identify some nodes near a known node

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Alberto Acri
Alberto Acri 2023-10-9
编辑： Fabio Freschi 2023-10-9
Is there a way to identify the upper and lower nodes of this geometry by knowing a node?
nodes = importdata("NODES.mat");
faces = importdata("FACES.mat");
P1 = [28.9646, -21.3886, 97.3614];
P2 = [17.2506, -22.7154, 62.1242];
figure
plot3(nodes(:,1),nodes(:,2),nodes(:,3),'k.','Markersize',2);
hold on
trimesh(faces(:,:),nodes(:,1),nodes(:,2),nodes(:,3),'EdgeColor','k','Linewidth',0.1,'Facecolor','b','FaceAlpha',0.2)
plot3(P1(:,1),P1(:,2),P1(:,3),'r.','Markersize',27);
plot3(P2(:,1),P2(:,2),P2(:,3),'r.','Markersize',27);
hold off
axis equal

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Fabio Freschi
Fabio Freschi 2023-10-9
编辑：Fabio Freschi 2023-10-9
Ran in:
You can use featureEdges. You get both upper and lower nodes, but it's not difficult to distinguish them
You can also check for nodes lying on the plane, as I suggested in yhe answer to your previous question here
nodes = importdata("NODES.mat");
faces = importdata("FACES.mat");
P1 = [28.9646, -21.3886, 97.3614];
P2 = [17.2506, -22.7154, 62.1242];
figure
plot3(nodes(:,1),nodes(:,2),nodes(:,3),'k.','Markersize',2);
hold on
trimesh(faces(:,:),nodes(:,1),nodes(:,2),nodes(:,3),'EdgeColor','k','Linewidth',0.1,'Facecolor','b','FaceAlpha',1)
plot3(P1(:,1),P1(:,2),P1(:,3),'r.','Markersize',27);
plot3(P2(:,1),P2(:,2),P2(:,3),'r.','Markersize',27);
% hold off
axis equal
TR = triangulation(faces,nodes);
E = featureEdges(TR,pi/3);
P = nodes(E(:),:);
plot3(P(:,1),P(:,2),P(:,3),'ro','MarkerFaceColor','r')

更多回答（1 个）

Matt J
Matt J 2023-10-9
编辑：Matt J 2023-10-9
Ran in:
It can help. The outliers in d below near correspond to the faces at the caps of the tube. Once you have these faces, you can use TR.ConnectivityList to determine the vertices attached to them.
nodes = importdata("NODES.mat");
faces = importdata("FACES.mat");
P1 = [28.9646, -21.3886, 97.3614];
P2 = [17.2506, -22.7154, 62.1242];
TR=triangulation(faces,nodes);
u=(P1-P2)/norm(P1-P2);
d=faceNormal(TR)*u(:);
plot(d,'x')

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