Author Topic: Mosaic combine  (Read 4410 times)

Offline Nigel Ball

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Mosaic combine
« on: 2010 October 11 11:45:00 »
I've recent;y ventured into Mosaic territory  O:)

I've got reasonable results using the Star Alignment and Pixel Math as per Juan excellent video tutorial. However, I have a question /comment.

From what I have experienced so far the Frame that is added to the source overlays/masks the source image where there is alignment. There is therefore a straight edge. Now straight edges are easy to see - great for the PixelMath operations but how about an option to have a jagged edge and or blending?
Nigel Ball
Nantwich, Cheshire, United Kingdom

Takahashi FSQ-106 at f/8, f/5 and f/3.6 on AP900, Nikon 28 mm and 180mm f/2.8
SBIG STL-11000M, Astrodon LRGB, 5nm Ha
ST-10XME, Astrodon HaLRGB
www.nigelaball.com

Offline Juan Conejero

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Re: Mosaic combine
« Reply #1 on: 2010 October 15 04:03:19 »
Hi Nigel,

Thanks for your nice words! Keep a few things in mind regarding mosaics:

- The manual frame adaptation procedure I described in the tutorial is no longer needed. StarAlignment has now an automatic frame adaptation feature that is much more accurate and efficient.

- You must always build your mosaics with linear images. Among other important reasons to work with linear images, the automatic frame adaptation algorithm won't work optimally with nonlinear images.

- For the frame adaptation routine to yield a seamless mosaic, individual mosaic frames must be accurately calibrated. In particular, flat fielding must be perfect, and if you have gradients, they must be fixed with DBE before building the mosaic. Irregular illumination will cause visible seams.

Quote
how about an option to have a jagged edge and or blending?

It isn't needed. The frame adaptation routine already applies the computed correction to the frame being added at each mosaic step. Or am I misunderstanding/missing something?
Juan Conejero
PixInsight Development Team
http://pixinsight.com/

Offline Nigel Ball

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Re: Mosaic combine
« Reply #2 on: 2010 October 15 12:41:24 »
Thanks Juan

Indeed I had a slight gradient on the edge of one of the frames. I had quite an overlap so cropping the frames down slightly removed this problem.

I tried the automatic Frame Calibration as well as the Pixel Math method. The latter is more satisfying  ;)

Anyway I've got my first mosaic  ;D
Nigel Ball
Nantwich, Cheshire, United Kingdom

Takahashi FSQ-106 at f/8, f/5 and f/3.6 on AP900, Nikon 28 mm and 180mm f/2.8
SBIG STL-11000M, Astrodon LRGB, 5nm Ha
ST-10XME, Astrodon HaLRGB
www.nigelaball.com

Offline Nigel Ball

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Re: Mosaic combine
« Reply #3 on: 2010 October 15 12:44:45 »
Or am I misunderstanding/missing something?

No - I was trying to understand how the mosaic function works in terms of how much of each frame overlap ends up in the final mosaic. It appears to me that the target frame is laid on top of the reference frame at the appropriate angle and position - is this correct? Rather than blending the two
Nigel Ball
Nantwich, Cheshire, United Kingdom

Takahashi FSQ-106 at f/8, f/5 and f/3.6 on AP900, Nikon 28 mm and 180mm f/2.8
SBIG STL-11000M, Astrodon LRGB, 5nm Ha
ST-10XME, Astrodon HaLRGB
www.nigelaball.com