SIRIL 1.4 question on -framing=max option

Hi,

Congrats on the 1.4 Beta release! One question for you…

I shoot Alt/Az so I often register and stack with -frame=max to create an output frame that encompasses all of the rotated input frames. It works great and I just crop as needed later, after stacking.

I also use the option to create animations of minor planets because the registered frames are all maximized and exactly the same dimensions.

With SIRIL 1.4, I noticed the registered frames are no longer the same dimension. It appears that perhaps you have optimized and instead use some reference to an offset for each image to properly alignment during stacking with the -maximize command. But if I load them up for an animation they are not all the same frame. This is a nice optimization as it saves space and, I expect, time.

However, how do I now register images and output registered and maximized images with the same frame sizes for use in my animations?

My process had been that I load up these registered images and batch crop them to my preferred animation frame in another tool. But not sure what my new process should be.

Hi Steven,

it’s indeed a choice we’ve made with the introduction of mosaics. You can easily imagine the space we save (and of course time because we don’t spend most of computing reading zeros). And as the number of options were growing we didn’t want to keep a mode where less advanced users would try out any option and flood their disk…
But we can try to figure a workaround. Can you describe exactly the steps you’re following? When you’re saying “animations of minor planets”, which feature are you using to register? “Asteroid/Comet registration”?

Cheers,

Cecile

Hi Cecile,

Thanks for the quick reply, I’m sure you are super busy!

I resister on stars as is usually done for deep sky, so the target moves across a fixed starry background.

Here are three examples:

  1. Asteroid Carnegia and the Crystal ball nebula:
  1. Dwarf planet MakeMake:
  1. Dwarf planet Haumea:

So I stack my data in 5 to 20 minute chunks (call these “substacks”) and then just stack these substacks once again in SIRIL and I use the registered substacks left in the “process” folder as my video animation frames.

Often I’ll batch crop them a bit before creating the video in PIPP, or afterwards.

I also sometimes stack my sub stacks interleaved so even though they may include 20 minutes of data they may be offset by only 10 minutes of time between stack so I can generate more animation frames.

Does this process make sense?

Also, I use a Script to do all this so I have directories listed as stack1, stack2, stack3, (up to 60) etc… and I just subdivide my lights into each directory and then run the script and it generates the master bias and flat and then goes into each directory and stacks them all, one after another, in one go, up to 60 directories.

I need to stack with -framing = max as I shoot alt/az and my targeting isn’t always perfectly centered on these dwarf planets.

SIRIL and the scripting is just perfect for this!

I do use other variances of this technique, but that’s the basic gist of it. One variant is I use the complete stack of all the data as the background and then find creative ways to copy the moving target into this field. I did that with Asteroid Thisbe going through the Jellyfish Nebula:

Hi Steven,

not as busy as one would expect, this beta release is going quite smoothly considering all the new features that we’ve introduced :smile: !

ok, so for your use case, the workaround is pretty simple, even though it requires an extra registration step:

  • align all your images as usual with the 2pass option
  • apply registration with framing=max
  • stack so as to have the big image
  • create a new sequence with all your images and the big stacked image
  • align this new sequence with the 2pass option
  • select the big stack as the reference
  • apply registration with framing=current

And there you go, you will have the black borders back!
If it fails at registering the new sequence (because the fov of the individual frames and the big stack are very different), you can use platesolving the sequence instead of global registration with 2pass. This will create the necessary registration information.

The method you described by creating multiple substacks is actually documented in one of our tutorials: Siril - Working with Comets
We’ve called it superstacking because, well, sounded good! FYI, I’ve written a sirilpy script (our new scripting interface that uses python) to replace all the scripts in this last section. It will be published with beta2.

Cheers,

Cecile

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Perfect! I’ll give this a try the next asteroid or minor planet capture and report back. It may be some time but I’m sure it’ll work.