Author Topic: Blind Solver  (Read 43985 times)

Offline georg.viehoever

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Blind Solver
« on: 2010 April 20 13:09:51 »
Hi,

as demonstrated in http://pixinsight.com/forum/index.php?topic=1853.0, I have created a script that automatically locates and labels astronomic images. The motivation for doing so was a session where I shot somewhere into the virgo cluster, but afterwards I was not able to determine what I had shot (I dont have GOTO, so finding the desired object often is quite a challenge...) . So I integrated the astrometry.net Blind Solver with PixInsight. The script still needs some polishing, but I wanted to share some results with you as soon as possible.

Below the original shot that got me started on this project. NGC4450 was on none of my maps...

Cheers,
Georg

Georg (6 inch Newton, unmodified Canon EOS40D+80D, unguided EQ5 mount)

Offline Carlos Milovic

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Re: Blind Solver
« Reply #1 on: 2010 April 20 13:14:53 »
Hey! That's great :)
Regards,

Carlos Milovic F.
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http://www.pixinsight.com

Offline Silvercup

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Re: Blind Solver
« Reply #2 on: 2010 April 20 13:51:54 »
Great, very usefull.

Best, Silvercup

Offline Ioannis Ioannou

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Re: Blind Solver
« Reply #3 on: 2010 April 20 16:07:10 »
Extremely interesting !!
Just as I was downloading the sources from astrometry.net for similar reasons.
I'm very interested to give it a try  :)

John
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Offline Ken Pendlebury

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Re: Blind Solver
« Reply #4 on: 2010 April 20 21:43:17 »
Wow... this is very cool.  Nice work!
Regards,
Ken
My Astro Photo Stream
http://www.flickr.com/photos/kenastro/

Offline Juan Conejero

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Re: Blind Solver
« Reply #5 on: 2010 April 21 01:48:41 »
Will you post your script soon? We are getting impatient! ;D
Juan Conejero
PixInsight Development Team
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Offline Niall Saunders

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Re: Blind Solver
« Reply #6 on: 2010 April 21 03:12:49 »
Will you post your script soon? We are getting impatient! ;D

Ha, ha, ha  ;D  ;D  ;D Juan,

Is this you "getting revenge" for everyone pleading with you to release v1.6 over the last few weeks !!!
Cheers,
Niall Saunders
Clinterty Observatories
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Offline georg.viehoever

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Re: Blind Solver
« Reply #7 on: 2010 April 21 11:25:06 »
Hi,

Will you post your script soon? We are getting impatient! ;D

I hope to be able to release the script within one week (that is: one week in Georg time scale  ;) ). But be warned: It needs you to install the astronomy.net software locally, and this requires you to compile the astrometry.net C-code. I did it on Fedora11-x64, but I think we should get it running on most UNIX like systems with almost zero effort - Windows probably requires more work. You also need some star database that you need to generate yourself, or a 4 GByte download. So this is not for fainthearts at the moment...

Attached is another example, this time from Harry's website http://www.harrysastroshed.com/Image%20html/ngc7331.html (used with kind permission by Harry).

Georg


Georg (6 inch Newton, unmodified Canon EOS40D+80D, unguided EQ5 mount)

Offline RBA

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Re: Blind Solver
« Reply #8 on: 2010 April 21 13:21:41 »
Very cool indeed. Re. fainthearts, if we cannot do the required steps, then we're just not worthy, end of story  ;D

Offline Harry page

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Re: Blind Solver
« Reply #9 on: 2010 April 21 13:48:03 »
Hi

Could have picked a better image  :P Not one of my best  ::)

Very nice work will have a go ASAP

Harry
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Offline Juan Conejero

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Re: Blind Solver
« Reply #10 on: 2010 April 22 02:25:36 »
Quote
one week in Georg time scale

As long as it isn't in Juan time scale all will be fine  :cheesy:
Juan Conejero
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Offline georg.viehoever

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Re: Blind Solver
« Reply #11 on: 2010 April 22 10:44:08 »
Hi Juan,

Quote
one week in Georg time scale
As long as it isn't in Juan time scale all will be fine  :cheesy:

You seem to have a more accelerated life than I do, and according to Einstein that results in time dilation... http://en.wikipedia.org/wiki/Time_dilation ;D.

To shorten the waiting for those living in my "time zone": Here labeled version of my Orion wide field http://pixinsight.com/forum/index.php?topic=1678.0.

Georg
Georg (6 inch Newton, unmodified Canon EOS40D+80D, unguided EQ5 mount)

Offline georg.viehoever

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Re: Blind Solver
« Reply #12 on: 2010 April 22 11:54:05 »
Hi,

let's get you started with the Blind Solver. In this article, I want to introduce you to the software that I use behind the scenes of the PI script (and that I did not write, I just use it in my script).

The Blind Solver is a product of a university project (of which I was not part), documented on http://astrometry.net/. If you are interested in how this software works, an article http://arxiv.org/PS_cache/arxiv/pdf/0910/0910.2233v1.pdf published by the project is probably the best introduction. Dustin Lang's thesis http://www.astro.princeton.edu/~dstn/ is an extended version of that. In essence, the Blind Solver works by creating a large database containing relative positions of groups of 4 stars (asterisms). When given an astronomical image, the Blind Solver identifies bright stars, and queries the database for the asterisms of those stars. Using the asterisms as fingerprints, it reduces possible positions/scales/rotations in the sky to a few candidates that can be validated using the other stars in the image. It can do so without knowing scale or rotations, because asterisms are invariant to these factors.

The result of the solver is center position, rotation, scale of the solved image, plus some more obscure information about the WCS coordinate system http://www.atnf.csiro.au/people/mcalabre/WCS/. This information can ultimately be used to label a star image, as I do in my application.

As far as I know, this capability is quite unique. Most of the astrometric tools I found on the web are only for "refining" already known star positions. Searching for more general tools, I found the PinPoint Astrometric engine http://pinpoint.dc3.com/ which is a commercial product. And I found the Elbrus Star Locator http://www.astrosurf.com/pulgar/elbrus/elbrusin.htm, which is open source. Both appear to require approximate information about image scale and rotation. When I tried Elbrus Star Locator, I could not convince it to solve my images. (I would be interested to hear if there are other programs solving this problem...)

Compiling the Blind Solver and installing the database requires some work. For those of us who want to give the Blind Solver a quick try, there are two options:
1. Register for the alpha version of the web service, as explained on http://astrometry.net/use.html, or
2. Upload your image to the astrometry group on Flickr http://www.flickr.com/groups/astrometry/ . The photostream of this group is screened by the astrometry.net Blind Solver web service, and annotations are added to your images automatically (sooner or later).

This, of course, is no option if you want to solve large amounts of images as I did for my Milky Way film http://pixinsight.com/forum/index.php?topic=1853.0, or if you want to use the Blind Solver to find the right position in the sky with your telescope. For that, you need the locally installed version of the Blind Solver, which usually solves an image within seconds. In the next forum article (maybe tommorow), I will give you some hints on how to install the Blind Solver software on Fedora 11 (which may also be helpful for other UNIXes).

Cheers,
Georg

« Last Edit: 2010 April 22 12:30:02 by georg.viehoever »
Georg (6 inch Newton, unmodified Canon EOS40D+80D, unguided EQ5 mount)

Offline avastro

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Re: Blind Solver
« Reply #13 on: 2010 April 23 00:00:15 »
Hi Georg
Thanks for pointing me to the Blind Solver, It's a promising program hopefully a windows version will be available.

Quote
As far as I know, this capability is quite unique. Most of the astrometric tools I found on the web are only for "refining" already known star positions. Searching for more general tools, I found the PinPoint Astrometric engine http://pinpoint.dc3.com/ which is a commercial product. And I found the Elbrus Star Locator http://www.astrosurf.com/pulgar/elbrus/elbrusin.htm, which is open source. Both appear to require approximate information about image scale and rotation. When I tried Elbrus Star Locator, I could not convince it to solve my images. (I would be interested to hear if there are other programs solving this problem...)
About other programs for solving plates let's share my experience.
I utilize Pinpoint witch is part of ACP an observatory control program for astro-photography from the same company.
Pinpoint allow solving plates or searching for asteroids or supernovas, a light version is incorporated in Maxim program allowing to solve plate independently.
Using Pinpoint, John Winfield made a free plugin for Maxim SkySolve "It is an application which is supplied an image and with no prior knowledge of where in the sky it was taken, it uses a star pattern matching algorithm and reference database to locate the correct image coordinates."
http://winfij.homeip.net/development/SkySolve/index.html
Also Astrometrica http://www.astrometrica.at/ is a nice and cheap program I use it for minor planets search.
 "Astrometrica is a interactive software tool for scientific grade astrometric data reduction of CCD images."

Cheers

Antoine

Antoine
Lentin Observatory
http://www.astrosurf.com/avastro/

Offline Ioannis Ioannou

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Re: Blind Solver
« Reply #14 on: 2010 April 23 00:34:50 »
It's a promising program hopefully a windows version will be available.

The code is based on U*ix flavor machines. Reorganizing it to work under Windows is , let say, complicated. And there are many dependencies on libraries that also have to be ported under Windows. The same , in smaller magnitude, should be true for porting (compiling) under Cygwin, a developers package that allows to port code from U*ix to Windows environments. See the file PORTABILITY inside the program's archive, it has some details.

For those that do not have experience with , eg, Linux, I suggest to download a program that can run virtual machines (eg VirtualBox) and also download a ready-made Linux image for this Virtual machine. Unfortunately such an image can not contain astrometry.net due to the license , or to be more precise, the program can be included since the license is GPL, but the indexes can not be redistributed, each individual should install them alone.

BTW, compiling on a Debian Linux (Lenny) box, with some of the standard developing tools already installed, was almost out of the the box, I just followed the instructions in README.

Just my 2 cents
Clear Skies
John (Ioannis)

FSQ106N+Robofocus+QHY-22+SX USB wheel+Baader filters
SX OAG+DSI Pro guiding a NEQ6
PI for the rest :)