Live stacking methods?

... or if the telescope slews to a new object?


Wouter

No problem with live -stacking, this for sure is a benefit, but making the Indi FITS viewer more reliable should have much higher priority. It still crashes to much taking the whole observation session down with it. Just hitting a button can already make it happen.
(last time it was the apply button after selecting log histogram). Please detach it from KSTARS before applying new functionality.

Rgrds,

Paul

I briefly experimented with the code. Serial stacking works. Running on my standard desktop the cycle time using existing files is about 1.4 seconds for each 2328x1760 monochrome image including applying a master dark and flat each time.

I also had a brief look to DSS live. That looks nice but somehow people are only using it in combination with AstroToaster. What's wrong with DSS live only?

I assume the main benefit is that this solution can be used in Linux. The other programs look pretty established in Windows.

What to do with the input files. Maybe delete? Renaming is possible but it will produce huge amount of data since the setup is most likely operated with short exposure times. If I work this concept further out, I don't want to add more options.

Flowchart for images A, B, C, D...:

result1:=A
plot result1
result2:=(result1*1+B )/2
plot result 2
result3:=(result2*2+C)/3
plot result 3
result4:=(result3*3+D)/4
plot result 4
result5:=(result4*4+E)/5
plot result 5
...

The images in the above process with master dark and flat & flats dark corrected
Viewer maintains the actual view position and zoom factor

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

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.

pch wrote: Hi,
But the best option is to do the stacking in 32bit floating point, then scale to 16bit for the display.
Patrick

Patrick, that' s no problem. ASTAP stacks always using floating point arrays.

Clear skies, Han

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.

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.)

I will introduce it on my blog.
Great job!

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.

pch wrote: Hi,
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.
Patrick

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

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.

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