PixInsight Drizzle fails

[Shelster1973]

Have just tried to integrate some data I have on M106 and the 1st part seems to go ok...that is the lights.

Have done this run using drizzle files just to see what difference they make....and my conclusion so far is that they mess up PI.

At the monent PI is 'updating drizzle data file' on the 4th of 30 images and has taken over an hour and seems to be getting slower and slower.

Computer is no slouch as have an i7 4790K with 32 GB of RAM, of which 16 GB is set up as a ram disc and used as swap files for PI solely.

Does anyone else have very slow running when using drizzle files or is it something that is unique to me?

Am going to leave it to run for the rest of the night and see where it gets up to......may end up not using drizzle file in the future.

Images are from a D7100 and are 6000 x 4000 and all data in PI is at 32 bit

Edit:- PI was unresponsive and crashed so have had to restart....

[Pompey Monkey]

That's a huge image to do drizzle on - no wonder your machine crawled back under the duvet!

TBH, I can't see what benefit drizzling would have at your imaging scale (less then 1.5" per pixel from a quick mental calculation), so I wouldn't lose any sleep over it. I experimented this week and the effects were barely  noticeable at over 3" per pixel.

[Shelster1973]

Cheers for that Pompey. Was thinking that may have been the issue. Guess I need a Cray or two.....

[Peakedge]

I have used drizzle only the once and whilst I think it 'seemed' to help reduce noise from the outset, it did introduce problems later on. My lights are from a Canon EOS 100d and are 5196x3464 pixels. I had no difficulty generating, updating or integrating the drizzle files but any subsequent action that was processor intensive such as denoise took several hours and even any simple action took quite a while, due to the size of the subsequent image.

Would I use drizzle again? Possibly, but only if I wanted to produce a very large format print or zoom right in to a particular detail in the image. Other than that, I would avoid. Silver linings and all that, it did quickly teach me to try out all my actions on small previews of the main image before committing to several hours of waiting for a process to complete. That said, I only have an i3 with 8GB of RAM and would welcome a Cray too!!

 

David

[Jokehoba]

I would second that it is your image size. My 1100D produces 4290x2856 raw images and on occasion drizzle does take a long time. Depends particularly on the number of subs to process. Drizzling 76x3min subs took hours! Updating the drizzle data is always the longest step. I too have an i7 but only 16Gb memory. 

I've not noticed any adverse effects that I could pin on drizzle. Any problems I've always traced back to calibration or poor flats. In fact, I include drizzle as an essential step in my workflow now, since it allows me to radically crop images where the target is small and so still retain a reasonable image.

Also, in recent months I have been dabbling with Ha/O3 NB filters. Not ideal on a DSLR (since only a proportion of pixels are capturing anything useful!). In this case drizzle is quicker (the raw frame is only a quarter the size) and I find improves resolution.

Stick with it. 

[Jokehoba]

Actually, just as a follow up... If M106 is small on your subs, you could use the same Dynamic Crop on all calibrated frames to make them smaller prior to integration. Then drizzle might be quicker.

Just a thought.

[Shelster1973]

Will give that a try and see how it goes....