How do i find the point of intersection between a line and a 3d surface? I have the data to plot the line, although the line is not straight (has a bend), whilst the surface is a cone section

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9/29/2010 2:08:21 PM

"Shenil " <shenilws@yahoo.com> wrote in message <i7vh8l$4rf$1@fred.mathworks.com>... > How do i find the point of intersection between a line and a 3d surface? > > I have the data to plot the line, although the line is not straight (has a bend), whilst the surface is a cone section You need to fit equations to these surfaces and to the line. With these equations, you can then solve for the intersection. If your bent line consists of 2 straight-line pieces, it is only relevant to fit the piece that intersects the surface with a straight line (if it is not piece-wise straight, then we shouldn't really be calling it a line, but rather a curve).

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9/29/2010 2:21:05 PM

"Matt J " <mattjacREMOVE@THISieee.spam> wrote in message <i7vi0h$sbh$1@fred.mathworks.com>... > "Shenil " <shenilws@yahoo.com> wrote in message <i7vh8l$4rf$1@fred.mathworks.com>... > > How do i find the point of intersection between a line and a 3d surface? > > > > I have the data to plot the line, although the line is not straight (has a bend), whilst the surface is a cone section > > You need to fit equations to these surfaces and to the line. With these equations, you can then solve for the intersection. > > If your bent line consists of 2 straight-line pieces, it is only relevant to fit the piece that intersects the surface with a straight line (if it is not piece-wise straight, then we shouldn't really be calling it a line, but rather a curve). Thanks for replying, i have the equation of the line and yes it is in 2 pieces, so need to consider both pieces. However, how do fit equations to the surfaces? Cheers

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9/29/2010 2:42:04 PM

"Matt J " <mattjacREMOVE@THISieee.spam> wrote in message <i7vi0h$sbh$1@fred.mathworks.com>... > "Shenil " <shenilws@yahoo.com> wrote in message <i7vh8l$4rf$1@fred.mathworks.com>... > > How do i find the point of intersection between a line and a 3d surface? > > > > I have the data to plot the line, although the line is not straight (has a bend), whilst the surface is a cone section > > You need to fit equations to these surfaces and to the line. With these equations, you can then solve for the intersection. > > If your bent line consists of 2 straight-line pieces, it is only relevant to fit the piece that intersects the surface with a straight line (if it is not piece-wise straight, then we shouldn't really be calling it a line, but rather a curve). By the way, the surface is created using surf

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9/29/2010 2:43:24 PM

"Shenil " <shenilws@yahoo.com> wrote in message <i7vj7s$lim$1@fred.mathworks.com>... > Thanks for replying, i have the equation of the line and yes it is in 2 pieces, so need to consider both pieces. ======= No, as I said you don't need to consider both, assuming you know which piece intersects the surface. In that case only the equation for the intersecting piece is relevant. >However, how do fit equations to the surfaces? ====== MATLAB has a Curve Fitting Toolbox http://www.mathworks.com/products/curvefitting/ There are also a number of curve/surface fitting tools on the File Exchange.

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9/29/2010 3:19:05 PM

Hello all: I used the following code to display color pixel distribution in 3D space. I = imread('fox.jpg'); R = I(:,:,1); G = I(:,:,2); B = I(:,:,3); plot3(R(:), G(:), B(:), 'r.'); Does matlab provide function to generate the minimum surface to cover all those pixels in 3D? So we can see the volume visualization of pixels in 3D space. Thank you -Daniel Alan Daniel Alan wrote: > > > Hello all: > > I used the following code to display color pixel distribution > in 3D space. > > I = imread('fox.jpg'); > R = I(:,:,1); > G = I(:,:,2); >...

I want to plot a 3D surface that is 0 to 4 on the x-axis, 0 to 1 on y-axis and 0 on the z-axis (or some z if necessary like 0 to 1). Then I want to plot peaks on that surface, given the x, y, and z coordinates of the peak on the surface. The data looks similar to: x y z 0.75 0.23 -2.86 0.75 0.47 3.87 0.75 0.64 2.78 2.45 0.23 4.56 2.45 0.47 0.89 2.45 0.64 2.74 3.23 0.23 2.10 3.23 0.47 -3.65 3.23 0.64 -5.89 Each row of the data is the x, y, and z coordinate of a specific peak on the 4 by 1 (0 to 4 on the x-axis, 0 to 1 on y-axis and 0 on the z-axis) surface. The ...

Hi all, I am trying to find the intersection of 2 lines in 3D. I have 4 points which I can use to construct 2 lines. I tried implementing the linear equations but I believe, its not giving correct intersection points. Can anyone help me in finding the intersection points in 3D? Any help would be appreciated !!! Thank you, chandp24@gmail.com wrote: > Hi all, > I am trying to find the intersection of 2 lines in 3D. I have 4 > points which I can use to construct 2 lines. I tried implementing the > linear equations but I believe, its not giving correct intersection > points. > > Can anyone help me in finding the intersection points in 3D? > Any help would be appreciated !!! > > Thank you, > Not sure what you mean by 'implementing the linear equations', but the following should work. Say your two lines are x = p1 + u*(p2-p1) y = p3 + v*(p4-p3) and you want the point of intersection, so x=y <=> p1 + u*(p2-p1) = p3 + v*(p4-p3) <=> u*(p2-p1) - v*(p4-p3) = p3-p1. The last line is an overdetermined system of linear equations (3 equations for 2 unknowns), which you can try to solve to get the (u,v) parameter values. There are 3 possible cases: - one solution (lines intersect in one and only one point) - an infinite number of solutions (lines lie on each other) - no solution (lines don't intersect and are either parallel (but not equal) or skewed) In the case of one solution, insert one of the parameter val...

Dear all, I have a set of 66 points forming a polygonal grid that can be viewed here: http://www.greyc.ismra.fr/~bailleul/These/meanshape.jpg My problem is to determine a smooth closed surface (always of sphere-eqvt topology) that (preferently) interpolates my unordered set of points. As you can see, it is difficult to group the points into "slices" of the same number of points in a given parametric direction, as we would need in the tensor-product scheme. I also considered different alternative methods, but all of them tend to demand a set of input points that are grouped into parallel packs of same cardinality. Could you advise me some references to help me out? -- = ----------------------------------- Jonathan BAILLEUL, Doctorant GREYC Image - Universit=E9 de Caen = http://www.greyc.ismra.fr/~bailleul "Jonathan.Bailleul" wrote: > = > Dear all, > = > I have a set of 66 points forming a polygonal grid that can be viewed > here: > http://www.greyc.ismra.fr/~bailleul/These/meanshape.jpg Apologizes for the "dead link" problems: our servers are down for now (maintenance) and should remain in that state due to a forthcoming storm. Do not hesitate to ask for an individual copy of the image I don't want to post on the newsgroup. Thanks in advance, -- = ----------------------------------- Jonathan BAILLEUL, Doctorant GREYC Image - Universit=E9 de Caen = http://www.greyc.ismra.fr/~bailleul Hi Jonathan Did you try...

1. Can I use Maple to plot scattered data? I have data set in (X, Y, Z, Value) pairs. 2. How can I find its fitting surafece? I found only this one http://www.maplesoft.com/applications/app_center_view.aspx?AID=2032&CID=10&SCID=148 thanks for your replies easy <easy.lin@gmail.com> writes: > 1. Can I use Maple to plot scattered data? > I have data set in (X, Y, Z, Value) pairs. You can plot scattered points in 3d using pointplot3d in the plots package. But I don't know what you want to do with the "Value". > 2. How can I fi...

I have set of data points obtained by sensor scanning the surface of a 3D object. I would like to reconstruct the surface based on the point cloud that I have now. Any advices on approach will help a lot. (I read the MATLAB help and found that griddata3 and related functions can fit surface. But I am not able to implement them !) please help out. Prasan In article <ef06ba6.-1@webx.raydaftYaTP>, Prasan <prasang@yahoo.com> wrote: > I have set of data points obtained by sensor scanning the surface of > a 3D object. I would like to reconstruct the surface based on the > p...

any can give matlab code for getting line-line intersection,line -plane intersection, traingle - plane intersection. aryan: <SNIP looking for code... > any can give matlab code for getting line-line intersection,line -plane intersection, traingle - plane intersection... lucky you... some very nice people have given this community great stuff... here are a few examples in random order <sebastian hoelz> <http://www.mathworks.com/matlabcentral/fileexchange/loadFile.do?objectId=8908&objectType=file> <duane hanselman> <http://www.mathworks.com/matlabcentral/fil...

Hello, I want to draw 3d lines on a 3d surface. I'm currently using plot3 and surf. The problem with that is there's often some odd clipping that occurs and the line doesn't totally lay flat on the surface because the lines are defined at a higher precision than the surface. What I was thinking of doing is making the 2d image, drawing the lines on it, converting it to cdata, and using it with warp to texture map the surface so it will look pretty and be totally flush with the surface. If I were to do that, I'd have to draw the 2d figure, do a getframe() and then use the outp...

Hi! I want the intersection point between a polygon and a line with a "start" point inside a polygon, and the "stop" point outside. I use a point in polygon algorithm to determin if the points are inside and outside. The line crosses only the polygon at one point. The polygon is not convex. Is there any C code available for these algorithms? Thanks! J-O Johansson Sweden janjo@home.se wrote: > Hi! > I want the intersection point between a polygon and a line with a > "start" point inside a polygon, and the "stop" point outside. I use a > point in polygon algorithm to determin if the points are inside and > outside. > The line crosses only the polygon at one point. > The polygon is not convex. That's a rather strange combination of problem parameters. How did you manage to end up knowing that, although the polygon is concave, there is only one intersection point of your edge with the polygon, but without knowing where that point is? -- Hans-Bernhard Broeker (broeker@physik.rwth-aachen.de) Even if all the snow were burnt, ashes would remain. On Tue, 31 May 2005 janjo@home.se wrote: > Hi! > > I want the intersection point between a polygon and a line with a > "start" point inside a polygon, and the "stop" point outside. I use a > point in polygon algorithm to determin if the points are inside and > outside. > > The line crosses only the polygon at one point....

I'm trying to solve the following problem. The points (1,2,3) are 2D (x,y). Using a robot arm, I can locate each point in 2D space using a sensor. If you imagine a line (I'll call it 'a') between points 1 and 2, extended so that you could draw a line('b') from point 3 which is at 90 degrees to the 'a' line. (this should be readable in a fixed-font) 1 a a a a 2 a a a ?bbbb bbbb bb3 The point at which these 2 lines intersect is point '?', is what I'm trying to find. Googling only really throws up finding the interesection if you have 4 points (2 to define each line) I cannot scan to find point '?' as the object is not exactly square and the corner is curved. Once I know point '?', I can pass points 1,? and 3 to the robot and it will generate a co-ordinate system based on the objects position and rotation and further manipulations will be possible. Thanks for any help, Jason On 17 Nov 2004 16:52:50 -0800, quietbiker@hotmail.com (Jason Clark) wrote: >I'm trying to solve the following problem. >The points (1,2,3) are 2D (x,y). Using a robot arm, I can locate each >point in 2D space using a sensor. >If you imagine a line (I'll call it 'a') between points 1 and 2, >extended so that you could draw a line('b') from point 3 which is at >90 degrees to the 'a' line. >(this should be readable in a fixed-font) ...

I have 3 circles that are defined by planes intersecting the unit sphere, and it is a given that each circle intersects the other two, but there is no point in common across all 3 circles. I am looking to find the point that minimizes the sum of the squared distances to each of the circles. Currently, I run a loop over man azimuth and elevation combinations, and just take a point on the unit sqphere that minimizes these distances. Is it possible to do a least squares solution and solve this directly? Thanks. -Steve Steve <srjm72499@gmail.com> wrote in message <1194306306.331377...

Hi everybody, I have a domain, square, with some random straight lines (with different slope) and I am trying to write code to show me graphically just the intersection points between different lines. Is there any body help me? Thanks, In article <ef554f0.-1@webcrossing.raydaftYaTP>, Ali <ali5738@yahoo.com> wrote: > Hi everybody, > I have a domain, square, with some random straight lines (with > different slope) and I am trying to write code to show me graphically > just the intersection points between different lines. Is there any > body help me? > Thanks, T...

Hi guys, I'm trying to find the line surface intersection in following program. For now I can assume that there is one and only one such intersection possible. The code works but I was wondering if anyone has any ideas improving the speed/performance. Is there something that can be vectorized or are there any other ways to improve speed? Best Regards, Peter clear all clc close all format long bf = false; % Flag for exiting loops after line-surface intersection is found. line_direction=[0.1;0;1]; line_vec_unit=1/norm(line_direction)*line_direction; l0=[.5;-0.51;1];...

I have a surface that I've created in 3-d space. It's similar to a hemisphere or dome. I also have 32x32 lines that are drawn perpendicular to that surface. I'd like to know if there's a way to calculate the points of the intersection between the line and the surface using matlab. Kelly Chmielewski wrote: > > > I have a surface that I've created in 3-d space. It's similar to a > hemisphere or dome. I also have 32x32 lines that are drawn > perpendicular to that surface. I'd like to know if there's a way to > calculate the points of the intersec...

Here is the coding. The question was, based on the different coordinates for single element antenna get the electric field strength, then find the intersection points. Can, anyone help me finding the intersection points? th=0:0.01:2*pi; d=0.5; n=1; for N=[3]; %number of antenna in array position E2=((sin((N*2*pi*d*sin(th))./2)./sin((2*pi*d*sin(th))./2))); figure(1) subplot(3,3,n) polar(th,abs(E2)) view([90,270]) n=n+1; end ...

Hi, I have a dwg file containing a layer with points and elevation values (note that the z coordination of the points isn't yet the value of the z elevation. How can I set the elevation of each point to the value (autocad text)? Next, can I get a surface, for some kind of interpolation, that covers all of those points? Typically to get a terrain surface from points. Thanks Check following website: www.cadtown.com YOu should be able to download routines to do what you want. Cheers, "damien" <damien.perret4@wanadoo.fr> wrote in message news:<c5oe6g$di$1@news-reader5.wanadoo.fr>... > Hi, > I have a dwg file containing a layer with points and elevation values (note > that the z coordination of the points isn't yet the value of the z > elevation. > How can I set the elevation of each point to the value (autocad text)? > Next, can I get a surface, for some kind of interpolation, that covers all > of those points? > Typically to get a terrain surface from points. > > Thanks 1. Go to: www.cadtown.com 2. Go to Add-on AutoCAD Section 3. Download the TXT2XYZ.ZIP which let you create a point file from autocad elevation texts 4. Download DTM2004.ZIP or DTM2n3.zip depending on your AutoCAD version. This will let you create a DTM or surface. You can even create a profile or section across DTM using DTMXS.zip if you want. Cheers, "damien" <damien.perret4...

Hi: I have a sparse data set to form a surface in 3D, and a line whose form is Y-Y0= A(X-X0)+B, i.e. I know a point at the point and the line direction of the line, how can i get the the intersection point of this line and the surface formed by sparse data points? Thanks Weihua Xiong weihua xiong: <SNIP line-surface-intersection problem... here's what <john d'errico> had to say in 2003: <http://groups.google.com/groups?selm=derrico-9E984B.21190622082003%40news.newsguy.com&output=gplain> us ...

undefined Hi that is pretty straighthforward math. what you need: plane equation: ax + by + cz + d = 0 two 3D points p1 and p2 ###################################################################### function p_out = intersect_plane_line(a, b, c, d, p1, p2) v = p1 - p2; l = - (a*p1(1) + b*p1(2) + c*p1(3) +d) / (a*v(1) + b*v(2) + c*v(3)); p_out = p1 + l*v; ###################################################################### hope that helps Peter ...

I have a 3d cubic spline constructed with the command csape that represent the surface of a human organ. This command returns a piecewise function that represent the surface. I need to find the intersection points of a line with the surface. How can I do this? ...

How can I make a better visualization of a three dimensional line in a MATLAB plot? I want to pick some points and indicate their x,y,z position with dotted lines to the axes. Is there a function in MATLAB or do I have to plot every line extra? "Nora " <nora.knaul_nospam_@tu-clausthal.de> wrote in message <fdg9gl$nmd$1@fred.mathworks.com>... > How can I make a better visualization of a three > dimensional line in a MATLAB plot? I want to pick some > points and indicate their x,y,z position with dotted lines > to the axes. Is there a function in MATLAB ...

Dear All, I am a MDL programer, I joined in this group recently and I have a one query if any body know please help me.. I want to findout the intersections of Complexchain and lineelements. Complexchain element is active dgn and Line element is Refereance. Please send me a code if any body have other wise give a suggetion. Thanks, Sriram. Use mdlIntersect_allBetweenElms(...) or one of the other mdlIntersect_... functions. Dan sri wrote: > Dear All, > > I am a MDL programer, I joined in this group recently and I have a one > query if any body know please help me.. > > I want to findout the intersections of Complexchain and lineelements. > Complexchain element is active dgn and Line element is Refereance. > > Please send me a code if any body have other wise give a suggetion. > Thanks, > Sriram. > ...

Hi, My trigonometry and imagination are failing me now. I hope some one can give me help. I have two points: Point2D.Double A = new Point2D.Double(100d, 100d); Point2D.Double B = new Point2D.Double(200d, 200d); which can be used to describe a line. Path2D.Double lineAB = new Path2D.Double(); moveTo(A.x, A.y); lineTo(B.x, B.y); I would like to find a third point that is: on a line perpendicular to lineAB, and double distanceC = 3d; distant from A double distanceB = Math.sqrt(Math.pow((B.x - A.x), 2) + Math.pow((B.y - A.y), 2)); My ultimate goal is to build a rectangle: Rectangle2D.Do...

Hello everyone, I am struggling to find a method by which I can know "whether a given line identified by two points on it, intersects a surface generated by the patch command" ? Is there a way out already in MATLAB or are there any work around ? Thanks, Sairam "Sairam Sankaran" <sairam.sankaran@gmail.com> wrote in message <gntdg5$95q$1@fred.mathworks.com>... > Hello everyone, > > I am struggling to find a method by which I can know "whether a given line identified by two points on it, intersects a surface generated by the patch command" ? ...

Dears Is there a tool that we can use to determine the intersection of 3D geometries. sincerely, toja ...

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