Coordinate Transformation - velocity?

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SUMMARY

The discussion centers on the transformation of velocity vectors from north-east-down (NED) coordinates to earth-centered-earth-fixed (ECEF) coordinates. The transformation matrix used for position vectors works correctly, but issues arise when applying it to velocity vectors. The key takeaway is that velocity, being a vector quantity, must adhere to specific transformation laws, as outlined in the book "Tensor Analysis" by Sokonikoff. Proper understanding of these laws is essential for accurate conversion of velocity vectors.

PREREQUISITES
  • Understanding of coordinate systems, specifically north-east-down (NED) and earth-centered-earth-fixed (ECEF) coordinates.
  • Familiarity with transformation matrices and their application in vector transformations.
  • Knowledge of vector quantities and their properties, particularly in the context of physics and engineering.
  • Basic understanding of tensor analysis and its relevance to vector transformations.
NEXT STEPS
  • Study the transformation laws for covariant and contravariant vectors.
  • Review the book "Tensor Analysis" by Sokonikoff for in-depth understanding of vector transformations.
  • Learn about the mathematical derivation of transformation matrices for velocity vectors.
  • Explore practical applications of coordinate transformations in fields such as geodesy and aerospace engineering.
USEFUL FOR

This discussion is beneficial for geospatial analysts, aerospace engineers, and anyone involved in coordinate transformations and vector analysis, particularly in the context of navigation and geodesy.

FrogPad
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If I have a velocity vector V in some coordinate system. Is there anything special that needs to be done to convert V -> V' ?

Basically, I have a matrix (N x 3) in north-east-down coordinates. I am trying to convert (a row at a time_ to another matrix (N x 3) to earth-centered-earth-fixed coordinates.

When I do the transformations with positions, it seems okay. When I do the transformation with velocity "positions" it seems messed up?


Any ideas?
 
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From,
http://en.wikipedia.org/wiki/Geodetic_system

The transformation matrix from ENU-coordinates to ECEF is:
16a633282014bfdae7efd24bfa65d47d.png

Figure 1 - Transformation Matrix


Working with this, I have found that when (x,y,z) and (Xr, Yr, Zr) represent positions vectors, the transformation works fine.

However, when (x,y,z) and (Xr, Yr, Zr) are velocity vectors... actually, I think I just answered my own question.

I only have (Xr, Yr, Zr) as a position-vector. And (x,y,z) as a velocity-vector.


Okay... how about this? In general terms, does Figure 1 - Transformation Matrix work for transforming velocity vectors?
 
FrogPad said:
If I have a velocity vector V in some coordinate system. Is there anything special that needs to be done to convert V -> V' ?

Basically, I have a matrix (N x 3) in north-east-down coordinates. I am trying to convert (a row at a time_ to another matrix (N x 3) to earth-centered-earth-fixed coordinates.

When I do the transformations with positions, it seems okay. When I do the transformation with velocity "positions" it seems messed up?


Any ideas?
There are transformation laws for a vector of rank-one either covariant or contravariant. Velocity is a vector quantity. it must obey a transformation law. For more detail check the book: Tensor Analysis by Sokonikoff
 

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