ImageSolver fails

[bparker]

ImageSolver had been working fine for me until about 2 weeks ago, and now it fails on most of my images, even the obvious ones. I assume I need to reset some parameters but I don't know which ones. Here is a run on M3:


Reading 1 image(s):
C:/Users/Bruce Parker/Pictures/evscope 2021 05 31/m3 evscope 2021 05 31.png

run --execute-mode=auto "C:/Program Files/PixInsight/src/scripts/AdP/ImageSolver.js"

Processing script file: C:/Program Files/PixInsight/src/scripts/AdP/ImageSolver.js

Searching in Sesame:

http://cdsweb.u-strasbg.fr/cgi-bin/nph-sesame/-oI/A?m3

1033 bytes transferred in 1.37 s @ 0.74 KiB/s

Gaia: Global context
8.600 us

Searching for optimal magnitude limit...

Gaia: Global context
1.214 s
Iteration 1: m=14.29, 363 sources found.

Gaia: Global context
489.844 ms
Iteration 2: m=15.72, 1430 sources found.

Gaia: Global context
787.757 ms
Iteration 3: m=17.29, 3000 sources found.

Gaia: Global context
1.674 s
Iteration 4: m=19.02, 9529 sources found.

Gaia: Global context
892.600 ms
Iteration 5: m=18.07, 4216 sources found.

Gaia: Global context
2.392 s
Iteration 6: m=19.88, 18170 sources found.

Gaia: Global context
1.588 s
Iteration 7: m=18.88, 8454 sources found.

Gaia: Global context
835.850 ms
Iteration 8: m=17.94, 3984 sources found.

Gaia: Global context
1.772 s
Iteration 9: m=19.73, 16528 sources found.

Gaia: Global context
1.548 s
Iteration 10: m=18.75, 7457 sources found.
* Using an automatically calculated limit magnitude of 18.75.
* Using the automatically selected GaiaEDR3_XPSD catalog.
Seed parameters for plate solving:
Center coordinates: RA = 13 42 11.620, Dec = +28 22 38.20
Resolution: 1.526 as/px
Starting StarAlignment iteration

Gaia: Global context
Executing Gaia EDR3 search command...
9713 sources found.
1.649 s
Catalog Gaia EDR3 (XPSD): 9713 objects.
* Using the triangle similarity star matching algorithm.

StarAlignment: Processing view: m3_evscope_2021_05_31
C:/Users/Bruce Parker/AppData/Local/Temp/stars.csv:
Scanning star data: done
7280 stars.
m3_evscope_2021_05_31:
Structure map: done
Detecting stars: done
2058 stars found.
* Reference image: Limiting to 2000 brightest stars.
* Target image: Limiting to 2000 brightest stars.
Matching stars: done
250 putative star pair matches.
Performing RANSAC: done
* Previous attempt failed - this is try #2
useScaleDifferences=true
* Reference image: Limiting to 2000 brightest stars.
* Target image: Limiting to 2000 brightest stars.
Matching stars: done
300 putative star pair matches.
Performing RANSAC: done
* Previous attempt failed - this is try #3
useScaleDifferences=false
* Reference image: Limiting to 250 brightest stars.
* Target image: Limiting to 250 brightest stars.
Matching stars: done
73 putative star pair matches.
Performing RANSAC: done
* Previous attempt failed - this is try #4
useScaleDifferences=true
* Reference image: Limiting to 250 brightest stars.
* Target image: Limiting to 250 brightest stars.
Matching stars: done
70 putative star pair matches.
Performing RANSAC: done
* Previous attempt failed - this is try #5
useScaleDifferences=false
* Reference image: Limiting to 125 brightest stars.
* Target image: Limiting to 125 brightest stars.
Matching stars: done
26 putative star pair matches.
Performing RANSAC: done
* Previous attempt failed - this is try #6
useScaleDifferences=true
* Reference image: Limiting to 125 brightest stars.
* Target image: Limiting to 125 brightest stars.
Matching stars: done
43 putative star pair matches.
Performing RANSAC: done
* Previous attempt failed - this is try #7
useScaleDifferences=false
* Reference image: Limiting to 60 brightest stars.
* Target image: Limiting to 60 brightest stars.
Matching stars: done
16 putative star pair matches.
Performing RANSAC: done
* Previous attempt failed - this is try #8
useScaleDifferences=true
* Reference image: Limiting to 60 brightest stars.
* Target image: Limiting to 60 brightest stars.
Matching stars: done
22 putative star pair matches.
Performing RANSAC: done
* Previous attempt failed - this is try #9
useScaleDifferences=false
* Reference image: Limiting to 30 brightest stars.
* Target image: Limiting to 30 brightest stars.
Matching stars: done
14 putative star pair matches.
Performing RANSAC: done
* Previous attempt failed - this is try #10
useScaleDifferences=true
* Reference image: Limiting to 30 brightest stars.
* Target image: Limiting to 30 brightest stars.
Matching stars: done
7 putative star pair matches.
Performing RANSAC: done
* Previous attempt failed - this is try #11
useScaleDifferences=false
* Reference image: Limiting to 15 brightest stars.
* Target image: Limiting to 15 brightest stars.
Matching stars: done
*** 0 star pair matches found - need at least six matched stars.
* Previous attempt failed - this is try #12
useScaleDifferences=true
* Reference image: Limiting to 15 brightest stars.
* Target image: Limiting to 15 brightest stars.
Matching stars: done
*** 0 star pair matches found - need at least six matched stars.
* Previous attempt failed - this is try #13
useScaleDifferences=false
* Reference image: Limiting to 8 brightest stars.
* Target image: Limiting to 8 brightest stars.
Matching stars: done
*** 0 star pair matches found - need at least six matched stars.
* Previous attempt failed - this is try #14
useScaleDifferences=true
* Reference image: Limiting to 8 brightest stars.
* Target image: Limiting to 8 brightest stars.
Matching stars: done
*** 0 star pair matches found - need at least six matched stars.
* Previous attempt failed - this is try #15
useScaleDifferences=false
* Reference image: Limiting to 500 brightest stars.
* Target image: Limiting to 500 brightest stars.
Matching stars: done
135 putative star pair matches.
Performing RANSAC: done
* Previous attempt failed - this is try #16
useScaleDifferences=true
* Reference image: Limiting to 500 brightest stars.
* Target image: Limiting to 500 brightest stars.
Matching stars: done
124 putative star pair matches.
Performing RANSAC: done
* Previous attempt failed - this is try #17
useScaleDifferences=false
* Reference image: Limiting to 1000 brightest stars.
* Target image: Limiting to 1000 brightest stars.
Matching stars: done
194 putative star pair matches.
Performing RANSAC: done
* Previous attempt failed - this is try #18
useScaleDifferences=true
* Reference image: Limiting to 1000 brightest stars.
* Target image: Limiting to 1000 brightest stars.
Matching stars: done
223 putative star pair matches.
Performing RANSAC: done
* Previous attempt failed - this is try #19
useScaleDifferences=false
* Reference image: Limiting to 3000 brightest stars.
Matching stars: done
325 putative star pair matches.
Performing RANSAC: done
* Previous attempt failed - this is try #20
useScaleDifferences=true
* Reference image: Limiting to 3000 brightest stars.
Matching stars: done
397 putative star pair matches.
Performing RANSAC: done
* Previous attempt failed - this is try #21
useScaleDifferences=false
* Reference image: Limiting to 5000 brightest stars.
Matching stars: done
377 putative star pair matches.
Performing RANSAC: done
* Previous attempt failed - this is try #22
useScaleDifferences=true
* Reference image: Limiting to 5000 brightest stars.
Matching stars: done
497 putative star pair matches.
Performing RANSAC: done
*** Error: Unable to find an initial set of putative star pair matches.
<* failed *>
*** Error: The image could not be aligned with the reference star field.
Please check the following items:
The initial coordinates should be inside the image.
The initial resolution should be within a factor of 2 from the correct value.
Adjust the star detection sensitivity parameter, so that the script can detect most of the stars in the image without mistaking noise for stars.
The catalog should be matched to the image. Choose the appropriate catalog and magnitude filter, so that the number of stars extracted from the catalog can be similar to the number of stars detected in the image.
*** Error: Unable to plate solve image: Alignment failed.
This usually happens because the initial parameters are too far from the actual metadata of the image.

 

[pfile]

C:/Users/Bruce Parker/Pictures/evscope 2021 05 31/m3 evscope 2021 05 31.png

please post this image to a file hosting site, set it to publick, and post the link here. it's basically impossible to debug this without access to the image you are trying to solve.

rob

 

[bparker]

https://app.box.com/s/ibfcv2iegidi2m6nujh7x19znpudwgog

 

[pfile]

ok - what is the image scale of this image, or what is the focal length of the telescope and the pixel size? has the image been resized from the original subexposures?

in general the image is stretched kind of hard, the star profiles are kind of flat, and the star shapes are not round, which might be contributing to the problem. without tweaking anything PI only saw 68 stars in the image.

rob

 

[bparker]

My guess is that it is poor collimation, probably a result of shipping the scope. I wasn't aware that this could affect the star alignment. Thanks for your time.

 

[pfile]

i'm sure it can be solved with a little help. so it is an RC8 or RC10? the "triangular" shape to some of the stars may indicate a "pinched" secondary, that is, the collimation screws are too tight and deforming the secondary.

rob

 

[bparker]

It is a Unistellar eVscope. The FL is 450mm. The pixel size is 3.75u. The image is not resized, though the on-board software creates a stack of 4 second images and also has to undo the effect of an alt-az mount.

 

[pfile]

ah ok. thought it might be an RC given the star shapes.

anyway i was able to solve the image with these settings (actually, these are the post-solve settings that indicate exactly the center and image scale. for whatever reason 450/3.75 did not work. i used 900/3.75. so i guess the image has gotten resized somewhere along the way.

 

[bparker]

I'm sorry. You are right about the resizing. Version 1.3 of the software increased the image size by 4x, 2x per side. I was using old specs. Good catch.

 

[pfile]

it's ok - ironically somehow after the first failed solve Imagesolver itself had "suggested" 900 (when i brought up the interface again after the failure it had a number in the large 800s populated there.) not sure if that was just random or was the result of the failed solve.