Dynamic alignment?

[simoninthelakes]

I'm 30 days into my 45-day trial and swaying towards "Let's buy this", but the lack of basic instructions for some processes is immensely frustrating. 

Having spent the best part of a day trying to work out dynamic alignment, it's time to ask for help.

Here's the problem:  I have fifty frames of ISON.  During the capture, the RA drive would occasionally stop.  Oops!  That means the comet is not in the right place on many frames to enable the time-interpolated alignment using "Comet Alignment".

I need to go through the frames manually and tell the alignment process "This is the comet" for each frame.

Is dynamic alignment the right tool for this please?  It only seems to align two frames.  I cannot for the life of me work out what the process might be.

Thanks for any help. 

Simon

[jkmorse]

Simon,

Don't give up.  It gets easier.

For the dynamic alignment tool, first open the two images, then the tool.  click on the one you are using as the reference image and you will see a little "1" with a check mark.  Then click on the second image and you will see a little "2" with a check mark.  It comes and goes fast though so you could miss it.  Then pick a star on the first image.  The program will put an "x" somewhere on the second image (often way in a corner).  It takes a bit of practice but you want to drag that "x" over the same star in the second image.  If you get it right, you should see similar stars in the little image boxes on the tool.  If you mess it up, you can just hit the red X and it will delete that attempt.  Do about 4 or five stars that way (the fourth and fifth should be dead on on there own.  Then click on the little green check on the bottom left of the tool to run the process.

By the way, I have put together a cribsheet that may help with some basics.  Here is an earlier version (I am constantly updating it for my own use).  It may be helpful in "cracking the code".

All the best and hope you stick around.

Jim

[jkmorse]

Simon,

Here is a link to a discussion thread where I attached a more recent version.  Its not the latest one but its better than the one I just attached to my note.  (not on my PixInsight computer at the moment so can't send the latest)

http://pixinsight.com/forum/index.php?topic=6260.msg42612#msg42612

Again, hope you stick around.

Jim

[simoninthelakes]

Jim, thanks for the reply and the encouragement (and the crib sheet!).  It's not one I want to give up on, as I can see the potential in the whole PixInsight program.

Unfortunately, I suspect my question wasn't clear as you appear to have kindly answered a rather different one.

I have 50 frames of a star field with a comet.  The comet moves against the stars and I want to align all the frames so that the comet is fixed and the stars will therefore trail.

There is a "Comet Alignment" process in PixInsight which uses the comet's position in the first frame and the last frame to interpolate where it should be in the intermediate frames, by reference to the time stamp on each frame.  Normally this would be fine, but as my RA drive stopped a couple of times during capture, the interpolation does not work because there isn't a consistent line between frame 1 and frame 50.

I want to be able to designate the comet in each frame, given that its movement from frame to frame is not consistent.  So I need a process that allows me to indicate the comet on each frame, rather than just the first and last with interpolation.  I was wondering whether the Dynamic Alignment process was the right one to use.

Since sending the original question, I have found a work-around:  first, Star Align all the frames, which recalibrates the interpolation from first to last, then second, Comet Align as normal.  This works well. In fact it is probably the solution, rather than just a work-around.

Thanks again for your response anyway!

Regards
Simon

[MikeOates]

Simon,

I had the exact same problem last week, but in my case only about 12 frames. The usual method is to do a star alignment on all the images, then run comet alignment on those frames. But, in my case all the stars were trails as I was guiding on the comet, so I could not use star alignment.

A workround (which was ok for about 12 frames) was to comet align one pair at a time, I use the starting frame as reference and then aligned one frame at a time. Tedious, especially if you have 50 to get through!

But if your stars are points, use star alignment first.

Mike

[simoninthelakes]

Thanks Mike, I think I was reaching the conclusion that each frame pair would have to be matched individually, but wasn't relishing the prospect of doing that manually 49 times.  I feel for your dilemma, guiding on the comet - that's a tough one.

Yes, my stars were points and the solution was indeed the obvious one, which of course occurred to me as soon as I had posted the original query!

Regards
Simon