Moon image registration

Rob Friefeld

Active member
Oct 11, 2012
34
0
"Just for fun", I set up on my front balcony and took some moon shots with a DSLR, 24 subs. I'm a bit embarrassed to say that I have no idea how to register the subs in PixInsight. The registration process worked pretty well the first time, with 3 of the 24 subs skewed and twisted afterward. When I tried to do it again, I couldn't get registration to work at all: it reports no stars found. I assume that the process picks up little high lights and considers them to be stars? The integration looked good noise-wise, but was not quite as sharp as any individual sub.

I'm not unhappy with the result, but how do I do this right?

FSQ-106 at f/8, 21 x 1/100th second at ISO 100. No calibration. Registered, integrated. Mild deconvolution, histo stretch, HDMRT, LHE.

http://frie.net/Moon.jpg[/url
 

pfile

PTeam Member
Nov 23, 2009
5,625
105
i think yes, lunar image with staralignment is a happy accident. there was a tutorial thread posted here with best settings for StarAlignment to interpret bright parts of the moon as 'stars', but now i can't remember who posted it.

you can also try the script called FFTRegistration which does a more traditional FFT-based planetary-style alignment.

rob
 

cdesselles

Well-known member
Nov 1, 2013
164
0
69
Denham Springs, LA USA
Try the "HDR Composition" process.  Essentially you'll be making a mosaic of all the images, but since they are all the same they should be overlaying each other.

(I've not done this myself, so if you try it, please report on it so I can see if my guess is correct.)
 

Rob Friefeld

Active member
Oct 11, 2012
34
0
GradientMergeMosaic did work. The result looks pixel identical to register-integrate, but it was certainly simpler. Thanks!
 

MikeOates

Well-known member
Dec 13, 2012
278
0
pfile said:
There was a tutorial thread posted here with best settings for StarAlignment to interpret bright parts of the moon as 'stars', but now i can't remember who posted it.

rob
Hi Rob, Was it my post?
http://pixinsight.com/forum/index.php?topic=7214.msg48564#msg48564

Mike
 

RogueSquadron

New member
Aug 1, 2020
4
0
Hello,

I am constantly failing with integration of my Moon subs. I tried different exposure setups to come up with images to be stretched and even bright enough without stretching. FFTRegistration worked once (the first time) then never again.

As I am on Mac, I don't have much alternatives and would really like to get this going in PixInsight.

Attached is the result of my latest try to stack 100 debayered 0.01 secs images with FFTRegistration.

Any help is much appreciated.

Amin

Moon Fail 2.jpg
 

RogueSquadron

New member
Aug 1, 2020
4
0
I played around a little more with this and realized once I calibrate the lights with flats it does not work anymore. Bias and dark calibration is fine, as soon as I add flats the algorithm does not detect the offset between the single images anymore and the blurry image above results.

Any hints what I am doing wrong?
 

pfile

PTeam Member
Nov 23, 2009
5,625
105
how do the flattened subs look? do they look OK?

what i've usually done in cases like these is to crop the input images to the largest box that will fit the start and end frames. you can do this with blink - zoom in on the image and move the green box around, and the movie button will crop and output the files in whatever format you want. the files will still go out to disk even if you don't have ffmpeg installed (so it is OK if the final step fails.)

somehow getting the moon (or sun) near the center of the image seems to help FFTRegistration figure out what's going on.
 

RogueSquadron

New member
Aug 1, 2020
4
0
Hello,

thanks a lot, that fixed it. The flattened images look fine and now FFTRegistration is able to stack them just right!

But the right cropping seems to be VERY important. I tried a 2nd run and wanted to put the Moon in the middle, so the first framwould have black space right and on bottom and did not work again.

Cheers

Amin
 

pfile

PTeam Member
Nov 23, 2009
5,625
105
well, you can always use the Crop tool to reframe the final image. you can put positive values in the margins/anchors boxes and the image will be increased in size by however many pixels you enter on each side.