Continue live stack from previous session

[JimsShed]

Hi Robin,
I would like to continue a live stack from a previous session.
Eg; My camera is a 294MC Pro. Last night I used Live Stack to take 50 frames of M42. Tonight I want to add to those 50 frames in a continuation of the same stack.

As a suggested use case, I would start my camera, but also specify a live stack source folder. When I click the Live Stack button it would restack everything in that folder and then continue the normal acquisition.

So a bit like live stacking the Folder Monitor camera, with a continuation of input from a live camera.

Some benefits of being able to do this;
1) Go back and remove bad frames that have occurred in the current session (planes, satellites, bumped mount, etc)
2) Build on EAA image quality using previous data.

Any thoughts?

Regards, Jim

[admin]

Hi Jim,

an interesting idea - I had given some thought to being able to resume a stack, but had imagined that SharpCap would save the current stack state and then reload it later, rather than reprocessing the previous frames. There are advantages to both approaches - the removal of bad frames is a good point for your approach, but it does require raw frames to be saved and also a potential delay while the old frames are re-stacked.

I will keep this idea in mind.

cheers,

Robin

[mgCatskills]

Perhaps this has already been proposed, but a related thought triggered by your comment, Robin, would be to allow the user to establish a buffer of a set number of frames and give them an "unstack" button that works with them. Nothing worse than having a nice stack ruined by a wide satellite trail right down the middle.

[admin]

Hi,

yeah, that 'unstack' option is something worth thinking about - it's probably best done by running the problem frame through the stack in 'subtract' mode, which is exact for default stacking, and should give pretty decent results for sigma clipped too...

An unstack last frame button would be (relatively) easy, but do you always spot something like that straight away - my experience is no, so really you would need some sort of frame history display to click through I guess...

cheers,

Robin

[carlomuccini]

In my opinion, resuming the stack from the last time doesn't make much sense, both because the stacks can be added later and because it's impossible for the camera to be in exactly the same position.
Instead, it happens more and more often that during the 15-minute live stack, of 15s of exposure, a satellite passes by and leaves a very obvious trace. If it happens to me at the beginning, in the first 30-45s, I delete and start again, otherwise I'll make my peace with it. So the possibility of deleting even just the last frame acquired would be really useful.

Carlo

[mgCatskills]

I don’t always notice satellite trails immediately but I often do. So undo only the last frame would be much appreciated. Several frames would be better than 1 but there’s definitely diminishing returns after 4 or 5.

[admin]

Yep, I think that is an accurate assessment - a three or four frame lookback would be nice, but if you haven't noticed immediately then you need to be able to click through the previous frames to find the one with the issue. That makes things more complex (not least because you may not even see the trail without a stretch applied to the raw frame).

I have a prototype now with last frame unstack which seems to work, although I need to check that all the book-keeping of frame counts, total exposure, etc are being wound back consistently when a frame is removed and that there are no nasty side effects!

cheers,

Robin

[carlomuccini]

>>>I have a prototype now with last frame unstack
Even just one would be very good!

Carlo

[mgCatskills]

I updated SharpCap yesterday and observed for the first time in a month (was in England and Scotland for 2 weeks and then recovering from COVID).

I saw the "Unstack" button for the first time. "Holy, Cow, Batman!" Nice job.

While I agree that a 3 or 4 frame unstack would be better than the last one only, I don't think you need to over-complicate it. Like a lot of EAA'ers, my exposures are pretty short - generally 30s or less . If I have to throw away a couple of good frames to get rid of the one with the satellite trails, that's fine by me and worth it. No need to build a "search" GUI to find the problem frame - just allow us to undo another frame up to whatever frame limit we can. Of course, I'd want an undo/undo in case the problem is not fixable. Would hate to throw away, say 4 frames, if that's the limit, only to find that the satellite hit before that and I'd thrown away 2 minutes of capture time (and the first 2 minutes of reducing satellite trails) without any effect.

[admin]

Hi,

thanks for the feedback - that's an interesting approach to basically treat it like an undo button so you could go back more than one frame (right now, it's just one frame). If you have plenty of memory (or are saving RAW frames) then there would be the possibility of finding the previous frame once you have used the button once, so it is good to go with a second undo...

I will have a think about that approach - I guess the issues are...

1) If you go back 2 or 3 frames and still don't reach the culprit then you might want a 'redo' button
2) It all becomes complex once a new frame arrives while you are busy undoing old ones

cheers,

Robin