<pre><code>While the shift file looks nearly identical to the prior run, 
this is because the axis-dependent rotation 
and scale values are averaged together in the shiftfile. 
To determine the actual values, it is necessary to inspect the logfile.

j9irw5kaq  SCALE_X: 1.000008792  SCALE_Y: 1.00000757  ROT_X: 0.002818152  ROT_Y: 359.998708  SKEW: 359.9958898
j9irw4b1q  SCALE_X: 0.999986877  SCALE_Y: 1.00003072  ROT_X: 0.004877188  ROT_Y: 0.00405990  SKEW:  -0.0008173   
</code></pre>
<p>The above script is related to the axis explanation of fitgeometry=general of drizzlepac.tweakreg.TweakReg.
(and this is from <a href="https://github.com/spacetelescope/notebooks/blob/master/notebooks/DrizzlePac/align_multiple_visits/align_multiple_visits.ipynb" rel="nofollow noreferrer">DrizzlePac tutorial</a>)</p>
<p>How are there two different rotation with respect to &quot;x axis&quot; and &quot;y axis&quot;?</p>
<p>In two-dimensional space, there is just one rotation with x-axis and y-axis separately, NOT two rotations.</p>

CC BY-SA 4.0
2022-08-06T12:03:09.700Z
Screenshots of text are strongly discouraged in Stack Exchange, especially when you can just copy/paste the actual text. If you add four spaces in the beginning of the line your code-like items will display as a code block (equal spaced font) `like this`. *Thanks!*
uhoh
CC BY-SA 4.0
2022-08-06T14:30:29.847Z
Two possibilities: 1. The ROT_X and ROT_Y values differ by less than the errors, and so are not actually different; 2. A real difference could be an indication of a *distortion*, which cannot be accurately represented by a uniform rotation.
Peter Erwin
CC BY-SA 4.0
2022-08-07T00:32:35.667Z
@ago Thank you for good comment. I edited it.
BAO
CC BY-SA 4.0
2022-08-07T00:35:27.873Z
@PeterErwin Thank you, but what's the meaning of uniform rotation of "possibilities 2"? Can we rotate the x-axis and y-axis separately?
BAO
<observational-astronomy><drizzle><tweakreg>
In the explanation of fitgeometry=general of drizzlepac.tweakreg.TweakReg, How are there two different rotation with respect to "x axis" and "y axis"?
BAO
# In the explanation of fitgeometry=general of drizzlepac.tweakreg.TweakReg, How are there two different rotation with respect to "x axis" and "y axis"?

(Asked by: username_0 on 2022-08-06)

```
While the shift file looks nearly identical to the prior run, 
this is because the axis-dependent rotation 
and scale values are averaged together in the shiftfile. 
To determine the actual values, it is necessary to inspect the logfile.

j9irw5kaq  SCALE_X: 1.000008792  SCALE_Y: 1.00000757  ROT_X: 0.002818152  ROT_Y: 359.998708  SKEW: 359.9958898
j9irw4b1q  SCALE_X: 0.999986877  SCALE_Y: 1.00003072  ROT_X: 0.004877188  ROT_Y: 0.00405990  SKEW:  -0.0008173   

```

The above script is related to the axis explanation of fitgeometry=general of drizzlepac.tweakreg.TweakReg.
(and this is from [DrizzlePac tutorial](https://github.com/spacetelescope/notebooks/blob/master/notebooks/DrizzlePac/align_multiple_visits/align_multiple_visits.ipynb))

How are there two different rotation with respect to "x axis" and "y axis"?

In two-dimensional space, there is just one rotation with x-axis and y-axis separately, NOT two rotations.

**Tags:** observational-astronomy, drizzle, tweakreg

> **Comments:**
> **username_1**: Screenshots of text are strongly discouraged in Stack Exchange, especially when you can just copy/paste the actual text. If you add four spaces in the beginning of the line your code-like items will display as a code block (equal spaced font) `like this`. *Thanks!*  
> **username_2**: Two possibilities: 1. The ROT_X and ROT_Y values differ by less than the errors, and so are not actually different; 2. A real difference could be an indication of a *distortion*, which cannot be accurately represented by a uniform rotation.  
> **username_0**: @ago Thank you for good comment. I edited it.  
> **username_0**: @username_2 Thank you, but what's the meaning of uniform rotation of "possibilities 2"? Can we rotate the x-axis and y-axis separately?  

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## 0 answers

