Line intersection in lawbview 7.1

hi
i m using labview 7.1 for sme image processing
i have detected 4 circles in an image which are in the following fashion
                                       1
                                    2     3
                                       4
From the IMAQ find circles option, i get the following data:
pos x     pos x     pos x     pos x    - this is the x pos of the center
pos y     pos y     pos y     pos y   - this is the y pos of the center
radius    radius    radius   radius   - radius in pixel
core       core      core      core     - area in pixel
now i have to find the intersection of the lines passing through the centers of the (1st,4th) & (2nd,3rd) circle centres.
the line intersection option is asking for the co ordinates of the points of the 1st & 2nd line . How can i give the point co ordinates from the circle data?
i.e for the 1st line i must enter the x & y coordinates of the center of 1st & 4th circle and for the 2nd line, x & y of the centers of the 2nd & 3rd cirlces
how can i do it?

james bond,
I'm glad to hear that the snapshot helped. As far as calibration, I believe that you are wanting to set up a calibration in LabVIEW, right? It sounds like you know how to set up calibrations in Vision Assistant. One of the more common ways to calibrate an image using a sheet of paper with a grid of dots on it with a known distance between the dots. This is talked about in more detail in this document which also has some helpful links at the bottom:
http://digital.ni.com/public.nsf/websearch/5FC615E2B4CFE8FA86256AC4007C9A42?OpenDocument
There are several sample programs for image calibration in LabVIEW, specifically in the Simple Calibration Example.vi. If you open that one you can see that they use a VI called IMAQ Set Simple Calibration.vi. This VI will handle calibrations when you input your image and the various calibration settings as in the example VI. What I would recommend, though, is to do your calibration in Vision Assistant like you were mentioning, then you can create LabVIEW code (Tools >> Create LabVIEW VI...) from it and it will create all of the VI's and settings you need to calibrate your image and use your calibrated image in LabVIEW. If I am misunderstanding please let me know. Thank you!
-Allison S.
Applications Engineering
-Allison S.
Calibration Services
Product Support Engineer

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Comments before have been pretty much on the money perhaps I might just add
Using the cola_markets example from the manual...
-- Return the topological intersection of two geometries.
SELECT SDO_GEOM.SDO_INTERSECTION(c_a.shape, c_c.shape, 0.005)
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2 3 4 5 6 7
MKT_ID NAME
3 cola_c
5 cola_d5
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) = 'TRUE';
2 3 4 5 6 7
MKT_ID NAME
1 cola_a
2 cola_b
4 cola_d
Cheers
Rich

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Line Intersection retuns point instead line segment

Hi all,
I want to intersect two lines with the function sdo_intersection (Oracle8i).
However, as result I get always a point instead of a line segment.
Any suggestions ??
Thanks Peter
Following the Script:
/* Table Theme2 */
CREATE TABLE THEME2(ID NUMBER, GEOM MDSYS.SDO_GEOMETRY);
/* Update Metadata */
INSERT INTO USER_SDO_GEOM_METADATA (TABLE_NAME, COLUMN_NAME, DIMINFO)
VALUES ('THEME2', 'GEOM', MDSYS.SDO_DIM_ARRAY
(MDSYS.SDO_DIM_ELEMENT('X', 2546727.982208079, 2629500.677188804, 0.000000050),
MDSYS.SDO_DIM_ELEMENT('Y', 5479508.594623252, 5585930.631027042, 0.000000050) ) );
COMMIT;
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insert into theme2 values (1,SDO_GEOMETRY(2002, 82015, NULL,
SDO_ELEM_INFO_ARRAY(1, 2, 1),SDO_ORDINATE_ARRAY(
2546727.98, 5570612.31, 2551027.86, 5558787.64, 2554252.77,
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mdsys.SDO_ELEM_INFO_ARRAY(1, 2, 1), mdsys.SDO_ORDINATE_ARRAY(
2619288.46, 5585930.63, 2613913.61, 5568731.11, 2608538.76, 5550456.62,
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from theme2 a, theme2 b
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The two lines you've provided intersect at a single point, which is by definition not a line.
If you want to return a line, then the intersection has to happen along some length of the line.
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data.
Your user_sdo_geom_metadata should include the srid value stored in the geometries.
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both geometries.
Regards,
Dan

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If i have a line with end points ( x1 , y1 ) ( x2 , y2 ) and
another line that crosses it, and its end points are ( x3 , y3 ) ( x4 , y4 )
how do i get the intersection point ( IPx , IPy ) ?

My maths is pretty shabby, but after a bit of playing around I came up with this
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Thank you very much for your response.
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What i'd like to do is select an open ended path, and generate an array of all the objects that path intersects. Here's an image to illustrate:
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Drawing object on the intersections point of 2 lines.

hi guys, im very new in actionscrip , please give me some guidance.
i'm doing this project , about 2 lines intersecting each other(the 2 lines are not always on the same position) . i try to find the intersections point using collision detection method but how do i place an object on the intersections point?
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then it's easier to calculate the intersection algebraically:
function intersectionF(x1:Number,y1:Number,x2:Number,y2:Number,x3:Number,y3:Number,x4:Number,y4:Number):Array {
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               var b2:Number = y3-m2*x3;
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               b2 = y3-m2*x3;
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The intersection point of two lines in 3D

How to calculate the intersection point of two lines in 3D?
source code!

this is actually a rather easy operation. lets look at some basic properties of lines / vectors in 3D space:
1. If two lines intersect at a single point, then there must be exactly one plane in which the two lines are co-planar. This is pretty trivial to prove, but I won't bother here, because you can google to find out that two vectors that extend from a common point define a single plane.
2. If you take the cross-product of two vectors, the resulting vector is guaranteed to be perpendicular to both lines (this is a basic property of a cross-product). If the two lines intersect, then this cross-product will be the normal vector to the plane in which both lines lie.
3. Now transform (rotate) yours space such that your z-axis becomes parallel to the normal vector of that plane.
Now, the parametric equation for a line in 3D space is this:
(x, y, z) = (xo, yo, zo) + k(xd, yd, zd)
After you have transformed your space, you will notice that the equation of each line will now be
(x, y, z) = (xo, yo, zo) + k(xd, yd, 0)
If zo is equal for both lines, then the two lines intersect. Otherwise, the two lines do not intersect.
if the intersection exists, then to solve for it, you ignore the z coordinate, and treat it like a two dimensional system:
(x, y) = (xo, yo) + k(xd, yd)
you can use the basic 2D formula y - yo = m(x - xo), or y = m(x - xo) + yo
you can calculate m = yd / xd.
which simplifies to y = mx -mxo + yo, or 0 = mx - y + (yo - mxo)
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From there, you can use Cramer's rule to find the intersection of the two lines.
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ii. cross-product of z axis (0, 0, 1) with cross-product of lines gives axis of rotation.
iii. rotate your lines (i.e. point and direction vector) about that axis by negative of ange determined in (i).
4. if z value of points from both lines is the different, no solution. stop.
5. otherwise, apply Cramer's rule.
6. done.
* obtaining the angle of rotation with the dot product relies on the angle being less than 90 degrees, so check if z value of normal vector is + or -, and then perform dot product and cross-product on appropriate + or - z vector.
- Adam

Intersecting lines

Hi, I am the greenest newbie alive. I am drawing with the pen tool (grrrrr not able to master) and when I have intersecting lines such as 2 s shaped curves the mid point has a gap so that it looks like someone erased part of one line. I am using 25 pt round brush. Also this is in CS 5.5 I have tried to highlight all the lines at once looking for some tool to change this and no luck I searched google for lines intersecting and gaps and nothing seems to fir my problem. Any help would be appreciate. Loving Illustrator so far.
Tim

Line Segment Intersection Checker

Hello all,
I am attempting to design a program that will take a set of n line segments and check which pairs of lines intersect. The lines are finite line segments, and they each have two end-points. I am supposed to be able to store a good amount of "Line Segments" into a data structure (Array, LinkedList, BinarySearchTree), etc. I am then supposed to be able to test each line segment against all of the other line segments that are read in in a text file in the format L1: (x,y),(x,y)
I figured out how to test whether or not two finite line segments intersect, that is not the problem. What I am concerned with is the method(s) I can use to read in all of the line segments and then output the intersecting pairs of line segments in the form (L1,L2) means Line segment 1 and Line segment 2 intersect.
I was thinking that reading the text file, I could just create an array with n slots that holds Line Segment objects (assuming I have created a Point class for keeping track of end-points), start with the first line segment in the array, and use the points from the first line segment's endpoints to all of the other line segment's endpoints in the array and check to see if they do intersect. Has anybody ever had to do something like this, and if so, what approach did you take to complete?
Thanks in advance.

Donojuana wrote:
... What I am concerned with is the method(s) I can use to read in all of the line segments and then output the intersecting pairs of line segments in the form (L1,L2) means Line segment 1 and Line segment 2 intersect.
I was thinking that reading the text file, I could just create an array with n slots that holds Line Segment objects (assuming I have created a Point class for keeping track of end-points), start with the first line segment in the array, and use the points from the first line segment's endpoints to all of the other line segment's endpoints in the array and check to see if they do intersect.
...That sounds like a good plan.

Finding a specific point on a rendered line

Consider the following class.
package com.somemythicalpackage
import java.awt.* ;
import java.awt.event.* ;
import javax.swing.* ;
public class DrawrALine extends JPanel implements MouseListener{
     private Point origin, terminus ;
     public DrawrALine(){
          super() ;
     public DrawrALine(Point _origin, Point _terminus){
          this() ;
          origin = _origin ;
          terminus = _terminus ;
          addMouseListener(this) ;
          render() ;
     private void render(){
          if(origin == null || terminus == null){
               return ;
          setBounds(origin.x, origin.y, (terminus.x - origin.x), (terminus.y - origin.y)) ;
     public void paintComponent(Graphics _g){
          _g.setColor(Color.BLACK) ;
          _g.drawLine(0, 0, getWidth(), getHeight()) ;
     public void mouseClicked(MouseEvent e){
          Point p = e.getPoint() ;
               Here's the question, how to determine if the Point p
               is on the line defined as being from (0:0) - (width : height)?
               Reason being that I want the program to respond when
               and only when the user clicks on the line, not if they
               click elsewhere within the bounds defined by the JPanel.
     public void mouseEntered(MouseEvent e){}
     public void mouseExited(MouseEvent e){}
     public void mousePressed(MouseEvent e){}
     public void mouseReleased(MouseEvent e){}
}In the actual application I am using this renderer class to draw lines semantically connecting objects in a graphical workspace. However, the type of connection has to be determined by the user. To that end ultimately I want to respond when the user double clicks on the line. Catching the double click is a trivial matter, but the struggle I am having is how to detemine if the user actually clicked on the line. The mouseClicked event fires anytime a mouse is clicked inside the bounds of the JPanel, and that doesn't accomplish what I need for two reasons. First, some of the bounding rectangles overlap so the user would be double clicking on the wrong connection. Secondly, it's sloppy to have the application respond because the user clicked in the same zipcode as the line.
(Right now I would give a lot for a 10th grade geometry book)
Regards, and thanks in advance for suggestions.
PS

Here's another way:
import java.awt.*;
import java.awt.geom.*;
import java.awt.event.*;
import javax.swing.*;
public class DrawLine extends Line2D {
   private String id;
   private Point2D p1, p2;
   public DrawLine(String _id, Point2D _p1, Point2D _p2) {
      super();
      id = _id;
      p1 = _p1;
      p2 = _p2;
      //addMouseListener(this);
      //render();
   public String getId() {
      return id;
   /* (non-Javadoc)
    * @see java.awt.geom.Line2D#getX1()
   public double getX1() {
      // TODO Auto-generated method stub
      return p1.getX();
   /* (non-Javadoc)
    * @see java.awt.geom.Line2D#getY1()
   public double getY1() {
      // TODO Auto-generated method stub
      return p1.getY();
   /* (non-Javadoc)
    * @see java.awt.geom.Line2D#getP1()
   public Point2D getP1() {
      // TODO Auto-generated method stub
      return p1;
   /* (non-Javadoc)
    * @see java.awt.geom.Line2D#getX2()
   public double getX2() {
      // TODO Auto-generated method stub
      return p2.getX();
   /* (non-Javadoc)
    * @see java.awt.geom.Line2D#getY2()
   public double getY2() {
      // TODO Auto-generated method stub
      return p2.getY();
   /* (non-Javadoc)
    * @see java.awt.geom.Line2D#getP2()
   public Point2D getP2() {
      // TODO Auto-generated method stub
      return p2;
   /* (non-Javadoc)
    * @see java.awt.geom.Line2D#setLine(double, double, double, double)
   public void setLine(double arg0, double arg1, double arg2, double arg3) {
      // TODO Auto-generated method stub
   /* (non-Javadoc)
    * @see java.awt.Shape#getBounds2D()
   public Rectangle2D getBounds2D() {
     return new Rectangle2D.Double(getX1(), getY1(), getX2() - getX1(),
                                                      getY2() - getY1());
   public static void main(String[] args) {
      JFrame f = new JFrame();
      final DrawLine[] lines = new DrawLine[10];
      Point p1, p2;
      for (int i = 0; i < lines.length; i++) {
         p1 = new Point(i * 10, i * 30);
         p2 = new Point(600 - (i * 10), 400 - (i * 30));
         lines[i] = new DrawLine("l" + i, p1, p2);
      LinePanel panel = new LinePanel(lines);
      panel.addMouseListener(new MouseAdapter() {
         public void mouseClicked(MouseEvent e) {
            Point p = e.getPoint();
            System.out.println("clicked at "+p);
            Rectangle2D.Double prect = new Rectangle2D.Double((double)p.x, (double)p.y,
                                                    (double)2, (double)2);
            for (int i=0; i<lines.length; i++) {
               if (lines.intersects(prect)) {
System.out.println("clicked on line " + lines[i].getId());
f.getContentPane().add(panel, BorderLayout.CENTER);
f.setSize(600, 400);
f.setVisible(true);
class LinePanel extends JPanel {
private Line2D[] lines;
public LinePanel(Line2D[] _lines) {
super(null);
this.lines = _lines;
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D)g;
for (int i=0; i<lines.length; i++) {
g2.draw(lines[i]);
Hope this helped,
Regards.

Line intersection in lawbview 7.1

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