Image Solve does not work

[wkrispler]

Hi,

I try to image solve my Monkeyhead nebula but unfortunately I do not suceed.
I always get the error message "Unable to find an initial set of putative star pair matches".

I attach the image and the settings I chose for the Image solve.

Thank you for your help!

Best,
Wolfgang

[vicent_peris]

Hi,

Your have two options to make it work:

- Lower the star sensitivity to -3.
- Change the align algorithm to "polygons", which is usually more robust.

In both cases, you'll be able to solve the astrometry. Usually this happens when we try to solve an already processed picture.

Best regards,
Vicent.

[wkrispler]

Hi Vicent,

thank you for your super fast reply.

Unfortunately the 2 options you mentioned do not work.

In the Pixinsight documentation it is mentioned that the default value for star sensitivity of -1 usually works well with linear images, a non-linear image (like mine) requires a higher value like 0-1.

So I do not understand why your recommendation is to lower the value to -3.

Any other idea what I could do to make it work?

Thank you,

Wolfgang

[msmythers]

Wolfgang

If the attached jpg is not the exact image you are trying to solve, can you upload the image to Dropbox or somewhere similar? It would make it much easier to determine why your having the problem. The attached jpg solved perfectly using Vicent suggestions.


Mike

[vicent_peris]

Hi Wolfgang,

It worked with the image you uploaded to the forum. You have the process icon attached to reproduce my process. Let me know if it works.


Best regards,
Vicent.

[wkrispler]

Hi Vicent,

thank you very much for your help.

I tried to set the star sensitivity to -3 and then the align algorithm to polygon and tried it on the jpg I uploaded- it did not work.

I also have problems with the process icon  - I loaded it via "Process Icon--> Load process icon" and tried to execute it on the jpg.
Error message: "Source code MD5 checksum mismatched..." -- actually I have never done that before...

Thank you,

Wolfgang

[vicent_peris]

I also have problems with the process icon  - I loaded it via "Process Icon--> Load process icon" and tried to execute it on the jpg.
Error message: "Source code MD5 checksum mismatched..." -- actually I have never done that before...

Hi,

Double click on the icon, then remove the MD5 checksum value (just by pressing the button right of the "MD5 checksum" field). Then, apply global the script tool to show the script interface.

Let me know if this works.

Best regards,
Vicent.

[vicent_peris]

By the way, this image was resampled. ImageSolver finds a 242 mm focal length when using 4.3 um pixels. This may be the problem...

V.

[wkrispler]

Hi Vicent,

wow!

With your script I tried it , it did NOT work. I got the error message "did not find putative stars...".

Thank you for the comment about the resampling. The image was taken with 600mm focal length but cropped!. I thought if I crop it I should use
the original focal length.

I tried it again changing the focal length to 250, then it worked. When I started your script again, the focal length was automatically changed to 241 , it worked again.

Strange!

So when I crop an image I have to change the focal distance in the script?

Many thanks Vicent!

Greetings from Salzburg,

Wolfgang

[vicent_peris]

Hi,

Not when you crop, but when you resize the image. ImageSolver needs an approximate image scale; in this case, you resized the image to 40% of its original size, so now the arcsecond per pixel value is more than double! Here is what the documentation of the script says:

The scale of the image can be defined using the fields Resolution or Focal length. These parameters don't need to be exact since the script is able to find its exact value. However the initial value should be as precise as possible since this increases the probability of the image being solved.

Best regards,
Vicent.