How to get the points on line or points which certain distance from the line

I have 3D matrix file where XYZ are lon,lat and height. I plot these XYZ value using scatter3. Now I want to plot profile of height (along a line in km) of the data where xaxis:distance along line in km and yaxis:Z value.In this case points (Z value) on the line for specific x and y value distance from the line will pick up for profile plot. I wrote the below code to do that but could not specify value for x and y limit to pick up the points on line and the points of certain distance from the line horizontally and vertically.

 X_start=-7.32;%starting X point for line A
Y_start=5.08;%starting Y point for line A
X_end=-7.23;%ending X point for line A'
Y_end=5.31;%ending Y point for line A'
X_h=-7.32;%X point to specify Horizontal distance
Y_h=5.09;%Y point to specify Horizontal distance
m=(Y_end-Y_start)./(X_end-X_start);%slope/gradient between Star and Ending point
b=Y_start-m*X_start;%intercept of Y
x=[X_start,X_end];
y=m*x+b;
%distance specify horizontally
d_h=sqrt((X_start-X_h)^2+(Y_start-Y_h)^2);%Specify the distance Horizontally
t=d_h;
v_X = (linspace(X_start,X_end,t))';%Line X
v_Y = (linspace(Y_start,Y_end,t))';%Line Y
F = scatteredInterpolant(X,Y,Z);%Scatter interpolation
v_Z=F(v_X,v_Y);%Finding query Z
% distacne calculation from Starting to Ending Point
v_X_ref=v_X(1,:);%Set first X point A as reference
v_X_ref=v_Y(1,:);%Set first Y point A as reference
for i=1:length(v_X)
    n=v_X(i,:);
    e=v_Y(i,:);
    d(:,i)=(sqrt((v_X_ref-e)^2+(v__ref-n)^2))/1000;
end

Please help me to solve this. Thank you!

[KSSV]

Please post properly define code ...few variables are not defined there.

[M]

You defined twice X_start, idem for Y_end and v_X_ref and maybe others...

[NS]

edit the post. Hope to hear from you soon.

[KSSV]

Undefined function or variable 'X_h'.

Error in Joke (line 13)
d_h=sqrt((X_start-X_h)^2+(Y_start-Y_h)^2);%Specify the distance Horizontally

[KSSV]

Undefined function or variable 'X'.

Error in Joke (line 17)
F = scatteredInterpolant(X,Y,Z);%Scatter interpolation

[NS]

Thanks for the response. This there are actual value. I select the X_start and y_start, X_end and Y_end like (X1,Y1) and (X2,Y2) to create line on the XYZ scatter plot.

[Vaidyanathan Thiagarajan]

Hi,

I am also getting the same error as above. Can you please post the full code?

I am not sure what is your question. However, it looks like you are trying to do some basic geometric operations with points and lines.

To sample points on a line, you can follow the ideas in this post :

https://www.mathworks.com/matlabcentral/answers/57624-create-many-points-on-the-same-line

To check if a point is on a given line segment, you can follow the ideas in this post :

https://stackoverflow.com/questions/328107/how-can-you-determine-a-point-is-between-two-other-points-on-a-line-segment

To compute the shortest distance between a line and point, you follow the solution in this post :

https://www.mathworks.com/matlabcentral/answers/260593-distance-between-points-and-a-line-segment-in-3d

Hope it helps!

Best Regards,

Vaidyanathan