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udvat

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About udvat

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  1. udvat

    Moving light with camera

      How can compute the CameraviewMatrix? 
  2. udvat

    Moving light with camera

    Hi Alundra, Thanks for your reply. I just know the camera position in world coordinate. I don't know the angle of rotation for X, Y, Z axis. So my question in the second part was how can I get that. If I know the angle, I can compute the rotation matrix. For question 1, I am computing light position in global coordinate. Say, initially my camera coordinate is aligned with the global coordinate system. camera is at (0,0,1) position. I compute the light position using elevation and azimuth angle. light.x=R*sin(slant)*cos(tilt); light.y=R*sin(slant)*sin(tilt); light.z=R*cos(slant);   now, if the position of my camera changes, say new position is (1,0,0). How can compute the new light position?
  3. Hello,   Question 1. I am implementing a ray-tracer where I am moving my camera in a circle around an object using the following: camera_x = rs * sin(angle);    camera_y= 0.0;    camera_z = rs * cos(angle);    The light that illuminates the scene is specified by an azimuth angle and elevation angle. I want to move the light with the camera so that the light direction does not change with the camera movement. How can I do that? I don't want to use OpenGL lighting, so it will be helpful if you can suggest the transformation I need to do so.   Question 2. I know the camera position in world coordinate as I am calculating those using the equations shown above. How can I calculate the camera rotation matrix? To solve the problem in question 1, I am thinking about transforming the light position from world coordinate to camera coordinate for each new position of the camera. However, for that I need both camera position (known) and orientation (how to calculate it?).    Thanks in advance.    
  4. udvat

    Sobel edge detector

    Thank you. This is what I was looking for.
  5. udvat

    Sobel edge detector

    Hi L Spiro,   My intention is not to detect edges in all directions. Say, for a given direction u, I want to detect edges that are alligned with this direction only. This u can be anything.
  6. udvat

    Sobel edge detector

      I do not agree. It will give me edges in horizontal and vertical directions. It's not for any arbitrary direction.
  7. udvat

    Sobel edge detector

    Thanks for your reply. I know how to make it work for horizontal, vertical and diagonal edges. Could you please add some more details for an edge which is not either of these types?
  8. Hi,   I need to find edges in an image in an arbitrary direction. I found sobel or other edge detectors work for horizontal and vertical directions only. Is it possible to extend these to work for any arbitrary direction?   Thanks in advance.
  9. udvat

    Gaussian distribution

    Thanks Jefferutitan. Your discussion helped me see different consequences of this problem. So far my understanding is that the rank may/may not follow the normal distribution. It will depend on the nature of the raw data, number of samples and the threshold value.
  10. udvat

    Gaussian distribution

    Thanks guys for your reply. I gave the example of student score just to give an easy example but it seems an inappropriate example. @ [color="#284b72"]jefferytitan: The score does not follow Gaussian distribution in the two cases you mentioned. But I mentioned that in my specific case the score follows Gaussian. If range of score is between 0 and 100 , its a log normal distribution. @alvaro: Yes you are right. But what if I set a threshhold and assume two scores are same if their difference is less than the threshold?
  11. udvat

    Gaussian distribution

    Say, I have score of n students and I know that the distribution of scores is Gaussian. Now if I assign rank to each student based on score (students with same score will get same rank), is the distribution of rank still Gaussian? If not, why? What is its distribution? Thanks in advance.
  12. udvat

    Gaussian distribution

    Say, I have score of n students and I know that the distribution of scores is Gaussian. Now if I assign rank to each student based on score (students with same score will get same rank), is the distribution of rank still Gaussian? If not, why? What is its distribution? Thanks in advance.
  13. No, I wrote a code myself. If you want, I can give it to you.
  14. Hi, The problem is solved. Thanks to all.
  15. I am getting error while compiling your code .
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