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INDI Library v2.0.6 is Released (02 Feb 2024)

Bi-monthly release with minor bug fixes and improvements

Live stacking methods?

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Hi,

Han, this is good if you add this function to ASTAP.

From my experience in CCDciel, it work better with a simple addition of each new frame. This is because people doing EAA don't really fear about star saturation but want the faint nebulae level to increase as quickly as possible. When you divide by the number of frame, you keep the faint nebula level very low, as it was on a single image, just with less noise. Also 60 x 5 sec. do not saturate more than 1 x 300 sec.
But the best option is to do the stacking in 32bit floating point, then scale to 16bit for the display.

Maybe with ASTAP you can also try to keep every frame to redo the full stacking each time, in this case you can use sigma clipping to improve the result. If I understand correctly this is what AstroToaster do.
And as Jasem say this can also be used to preview the result of a standard sequence, not only for EAA.

At the moment CCDciel shift the image with a single star alignment before stacking. This work fine with unguided mount but not with alt/az mount. It is good if ASTAP can also apply a rotation but this imply that more than one star can be measured in the frame.

Patrick
4 years 5 months ago #44711

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Replied by han on topic Live stacking methods?

The first ASTAP version (v0.9.278 ) with "Live Stacking" is available for Linux AMD64 and MSWindows. You can find the new feature in the stack menu under tab "Live stacking"



It will stack all file(s) in the specified directory. If it is finished it will wait for new file(s). If a file is detected which is 20 arcmin away from the previous files (idea Wouter), a new stack will be started automatically. You can save the stack results from the viewer menu .

I haven't tested under clear skies but it seems to work well. Please tell me if this is useful and report possible bug(s) or improvements.
To identify files which are processed , they are renamed to the extension *.fts. You can rename them back with the button at the bottom.

If it works well, then I will compile the program for Raspberry Pi.
Patrick, that' s no problem. ASTAP stacks always using floating point arrays.

Clear skies, Han
The following user(s) said Thank You: Jasem Mutlaq, T-Studio, Jim, Brian
Last edit: 4 years 5 months ago by han.
4 years 5 months ago #44721
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Replied by T-Studio on topic Live stacking methods?

very nice.
I was trying to list support for ASTAP in the wish list Ekos alignment module.

ASTAP's Solver is a great help when creating a remote environment with SBC.
4 years 5 months ago #44742

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Replied by T-Studio on topic Live stacking methods?

If live stacking can also be implemented, this is a solution that can integrate EAA into SBC.
(I expect it to be easy to navigate and browse remotely as previously posted.)
4 years 5 months ago #44745

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Replied by T-Studio on topic Live stacking methods?

I will introduce it on my blog.
Great job!
4 years 5 months ago #44746

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Replied by han on topic Live stacking methods?

Just released ASTAP version 0.9.279 with some minor improvement. Now the stacking will also restart if the exposure time changes. It also restart stacking when the mount position changes more then 0.2 degrees/12 arc minutes. In the previous version this maximum offset was set by mistake at 20 arc seconds only.
If for Sigma Clip stacking the program keeps all images in memory (e.g. 20 megapixels equals 80 mbyte), the memory usage will rise fast and processing time will increase. You could probably avoid this by using only the first ten images to find statistically the mean and standard deviation of each pixel and to use that to detect outliers in the next images. For the moment, lets first see how the average stacking works and performs. Average stacking using the serial calculation makes it fast and simple.

Han
4 years 5 months ago #44761

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Replied by han on topic Live stacking methods?

This evening, I had a chance to test the ASTAP live stacking during some clear sky moment between the clouds. Noted the following:

- Stacking works well!
Only there is something wrong with star detection because it didn't work well with H-alpha images and the normal stack routine has not problem with them.
- The switch-over between two different object doesn't work proper. While slewing the incoming images confuse the program. For the time being I just had to stop imaging.
- Unicode fonts didn't work well with my Win7 system.
- Memo containing the fits header is flashing too much.

Improvements will come.

Han

One example made during strong wind:
41x10 seconds live stacking with ASI1600 and HEQ5 mount. No guiding. No darks No flats.

The following user(s) said Thank You: Jasem Mutlaq, AstroNerd, Jose Corazon, Avocette
Last edit: 4 years 5 months ago by han.
4 years 5 months ago #44791
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Replied by han on topic Live stacking methods?

Except the switch-over, the other problems should be fixed in v0.9.281. But more testing is required. This is an early release to test the concept.

Han
4 years 5 months ago #44793

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Replied by T-Studio on topic Live stacking methods?

Mr.han

live stacking for EAA, please check Sharp CAP for windows app.
A slider that adjusts the brightness and color of the stacked images can be used conveniently for viewing.
4 years 5 months ago #44796

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Replied by Jasem Mutlaq on topic Live stacking methods?

wow these are impressive results indeed!! Really looking forward to integrating this feature as well with KStars, just after I finish the ASTAP astrometry integration. Great work Han!
4 years 5 months ago #44803

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Replied by han on topic Live stacking methods?


I will do. But sliders are already available.

I'm trying to modifying an application which was designed to stack images from a stationary telescope with guiding. No guiding is no problems as long you keep the exposures short. Currently there is a concept problem that the application doesn't know what's happening with the telescope. When your continuous imaging and move the telescope you get something like this:




This will stack since a part of the exposure is good but somewhere halfway the operator decided to slew. But this will spoil the stack. Looking into the FITS header of CCDCiel there is no keyword I could use to identify the start slew halfway the exposure. So you either have to 1) suspend imaging automatic after a slew command or 2) add information to the header indicating the mount has moved or 3) ASTAP reads out the mount position. 4) stop manually the exposures

This is something for Jasem (Kstars) and Patrick (CCDCiel) to advice. Step 3 is a big step, so option 1) or 2) look the better option. Option 1) looks to me the best option since imaging and slewing doesn't make sense and any image will be worthless. Maybe this is already available in Kstars, I'm not familiar with it.

Han
4 years 5 months ago #44806
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Replied by han on topic Live stacking methods?

Fixed some run time problem with ASTAP release v0.9.282. This version processes all my images from last night, good or bad. :)

Han
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4 years 5 months ago #44807

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