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INDI Library v1.8.1 Released (09 Sep 2019)

Monthly maintenance release INDI v1.8.1

Live stacking methods?

1 month 3 weeks ago
knro
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Live stacking methods? #44651

han.k wrote: The ASTAP commandline is specified here:

www.hnsky.org/astap.htm#astap_command_line

Han


Thank you Han! I just have to say again I'm in love with both HNSKY & ASTAP! The functionality in ASTAP puts KStars FITSViewer to shame. I have a couple of questions if you don't mind. I love the stacking feature. Do you think your star alignment routine can be used to perform *live* stacking?

Jasem Mutlaq
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1 month 3 weeks ago 1 month 3 weeks ago by han.k.
han.k
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Live stacking methods? #44654
Live stacking should be possible to add, but I have never understood the benefit of live stacking. I do stacking the next day or week(s). I sort the images on HFD, background (clouds), star level (transparency) and remove a few outliers due to poor guiding , upcoming fog, seeing and so on. Monochrome stacking is easy, colour images are much more demanding at could require some tweaking. In practice I stack the series a few times before I'm happy or I could decide the add more images later to get a better result.

In ASTAP you can add several object series and stack them in one session. Series will be stacked on object name and darks and flats will be selected automatically. So you could do something else in the time it is running.

What is the benefit of live stacking like DSS, Deep Sky Stacker is doing? Is it to save some time? My images are often stacks of more then one night to get a very good signal to noise level and to show the faintest details.

Han

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1 month 3 weeks ago
Ihoujin
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Live stacking methods? #44656
I am acquainted with many EAA observers (Electronically Assisted Astronomy). These folks are not interested in producing fully processed images, they simply enjoy something in between visual observation with the added sensitivity and detail provided by sensitive cameras, such as Mallincams. Their techniques are also well received at public stargazing parties. Typically EAA will live stack the last 10 to 100 short exposures. Exposures are frequently as low as 5 seconds up to 30 seconds. They also frequently do not save every exposure, but will output the current live stack. One trick they use on targets such as M42 to avoid overexposing the core is an HDR effect by live stacking 2 different exposure times.

INDI/KStars on Raspberry Pi 4, 4gb
Raspbian Buster with AstroPi3 script configuration
Skywatcher HEQ5 Pro Mount
Canon 600D Camera
Orion SSAG/ASI120mm @280mm Guide Scope
PHD2
Adafruit Motor Hat shield
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Generic Bluetooth Joystick.
Startech 7 port powered USB Hub.
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1 month 3 weeks ago 1 month 3 weeks ago by han.k.
han.k
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Live stacking methods? #44657
Ihoujin,

Okay that make sense. However is this not better suited for the acquisition/ imaging program? Programs like CCDCiel can do it all live in memory as nicely demonstrated here:



Han

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1 month 3 weeks ago
Ihoujin
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Live stacking methods? #44658
Yup, that's pretty much what they like. Great demo, I'll have to look into trying it some time. Thanks.

INDI/KStars on Raspberry Pi 4, 4gb
Raspbian Buster with AstroPi3 script configuration
Skywatcher HEQ5 Pro Mount
Canon 600D Camera
Orion SSAG/ASI120mm @280mm Guide Scope
PHD2
Adafruit Motor Hat shield
Adafruit GPS Module
Generic Bluetooth Joystick.
Startech 7 port powered USB Hub.

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1 month 3 weeks ago
wornish
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Live stacking methods? #44660
The fact that the RPi4 can use the USB3 bus makes a huge difference. Compared to using an SD card using an SSD connected to USB3 makes a massive difference.

Right now the RPi4 cant boot from USB3 but using the guide in the link below it can be made to use the faster port.

This link shows how to take advantage of this:

jamesachambers.com/raspberry-pi-4-usb-bo...or-ssd-flash-drives/

In my case, the storage benchmark results speak for themselves.

Storage benchmark using
Original SD card only the score was : 1025
With the SSD on USB3 it's : 8430.

It simply files, in fact, it's faster than my Windows 10 laptop.
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1 month 2 weeks ago
knro
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Live stacking methods? #44672
Yes, we've been looking to do something like that in KStars. I think we need a very fast star-matching algorithm (to know how to rotate/scale frame before integration) and then some averaging algorithm. It's mostly just as a way to see live how the image acquisition is going. It's also great for observatories with visitors..etc.

I wish there is a library we could use to make this easier, unless a developer steps in to implement it from scratch based on the existing algorithms in ASTAP and/or CCDCiel.

Noticed both programs seems to use Pascal as well :D

Jasem Mutlaq
Support INDI & Ekos; Get StellarMate Astrophotography Gadget.
How to Submit Logs when you have problems?
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1 month 2 weeks ago
han.k
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Live stacking methods? #44675
If the purpose is live viewing and to prevent saturation, there is no need for alignment. If you could expose a single image of 200 seconds (with good guiding), the equivalent is simply adding 40 x 5 seconds exposures together without alignment. If done in memory this will be simple having low CPU load and memory size requirements. The only penalty will be more readout noise.

Theoretical for live viewing it would be nice to apply FIFO, first in first out but that would require adding 40 image arrays together for every update. That will probably too much but maybe a stack of the last 10 exposures is feasible with the available computer processing capacity. Applying a dark will be then the 11th action. If you work backwards, you could try to add as much as possible historical images till a watchdog says enough. But it will take a lot CPU load and memory space.

In my opinion, Object Pascal is excellent tool for doing some complicated stuff fast.

Han

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1 month 2 weeks ago
stash
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Live stacking methods? #44678
A Lot of EAA users , which I am one, also use very fast OTA's , sensitive CMOS(but DSLR works as well !) or add Hyperstar which enables very short <10 secs exposures which are stacked and produce good details even after 3 or 4 images and not just one bright objects like M42.

it does not need to be a fully integrated into Ekos but an application that runs along side EKOS e.g. it could just be set up to monitor a folder of exposures - e.g. Astrotoaster style (Deep Stacker). Perhaps as PC CCDCIEL works well with Indi you could persuade PC to produce a stand alone (i.e. not part of CCDCIEL) application using just his "stacking" code. NOTE Astrotoaster allows real time colour (Color) etc adjustment.

Bottom line would a RPI 3/4 cope with stacking and not hinder other processors ?

Short exposure stacked images examples (especially see HiloDon from Hawaii) stargazerslounge.com/topic/276321-first-...ith-hyperstar-on-c6/

RPI3 Ubuntu 16.04 / AMD desktop Kstars under Ubuntu 16.04 Mounts :azeq6 ,SWAZGoTo

RPI3 Fedora testing out on AMD desktop Fedpra 28 - running kstars 2.9.4 , Indilib 1.7.4 ?????

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1 month 2 weeks ago
han.k
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Live stacking methods? #44679
On my standard desktop ASTAP can stack 10 monochrome images of 2328 x 1760 pixels in about 11 seconds using star alignment. Without alignment it will be faster. Since there is interest, I will do some testing with live unaligned stacking using most resent images from disk. The only parameter would be the number images or maybe better a time limit. If the performance is satisfactory, executables could be provided for all major operating systems.

What live stacking speed would be acceptable?

Han

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1 month 2 weeks ago
Herrhausen
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Live stacking methods? #44682

han.k wrote: What is the benefit of live stacking like DSS, Deep Sky Stacker is doing? Is it to save some time? My images are often stacks of more then one night to get a very good signal to noise level and to show the faintest details.


IMO the benefit and main purpose of live stacking is making deep sky objects accessible to visitors. What used to be the view of M42 in an eyepiece (with ppl standing in line waiting for their turn)now becomes an immediately visible M42 on a screen, readily visible for everybody. For the astrophotographer it does not offer any advantages over normal stacking IMO.
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1 month 2 weeks ago 1 month 2 weeks ago by han.k.
han.k
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Live stacking methods? #44683
Looking to some "live stacking" videos, I see the following requirements for a live stacking program for deep-sky:

1) Alignment of unguided images with an exposure time of a few seconds. (Nobody is guiding)
2) Showing intermediate results

This mean you have to stack differently. Assuming the images are A,B,C,D... then

Simple serial stacking:

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


The only question to ask when to restart serial stacking. If alignment fails a few times?

Han

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