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Author Topic: Tips for a mosaic  (Read 1256 times)

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Offline Roger B

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Tips for a mosaic
« on: 11:20:28, 16 January, 2016 »
Anyone share any tips for processing a Mosaic. 

It's the joining together really I'm quite capable of calibrating & stacking the individual frames.   

Rog
Scopes - TS65q, W/O 110 Triplet
Mount - EQ6 PRO via  Eqmod,  Rowan belt modded
Cameras - SX694, QSI583WSG,Lodestar Guidecam, GP-Cam, QHY5II.
TS 9mm OAG
Quantum 7x1.25 EFW, Baader LRGB,Ha,OIII,SII Filters 
Quark chromo

SGPro, Pixinsight.

************AND NO TIME TO USE IT************

Offline chris.bailey

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Re: Tips for a mosaic
« Reply #1 on: 11:43:38, 16 January, 2016 »
Rog

I have spent an age developing a workflow for this. The problem is that at widish fields of view, frame distortion causes lack of match at the edges. Its fine with a couple of frames but on a 2x2 mosaic, frame 4 is a struggle to match. What I have done the last couple of times is as follows.

1) Image integration as normal. Avoid wildly different number of subs and duration contributing to the stack. I would now apply Mure De-Noise to each contributing frame immediately after integration.
(1a) Linear fit all frames to a reference - see below)
2) Crop any border artefacts and try to avoid bright stars straddling the crop or close to the cropped edges that will overlap with other frames.
3) DBE to remove any serious gradients, particularly at the overlap edges.
4) Use Image Solver in PI to plate solve each frame. This adds WCS co-ordinates to the .fits header.
5) Use Mosaic by Co-Ordinates in PI to register the Plate Solved frames. This creates a new file _registered for each with an overall size of the full mosaic. The individual frames are bent and buckled to match up. NB VERY processor intensive. Took about an hour with a 2x3 mosaic of veil.
6) Build the mosaic using Gradient Merge Mosaic from the _registered images. You may have to play with the settings to avoid jump discontinuities and in some cases go back and change the crops to avoid bright stars in the overlap. If some frames are brighter and this shows in the final mosaic go back and apply step 1a.

It may sound like a bit of a faff but I have used it successfully on 1x2 up to 2x3 mosaics. It is not reliant on having much overlap as each mosaic frame is plate solved to WCS so its position is known. Gradient Merge makes a fine job of feathering out the overlaps.

Chris


LX200|ZS70|FSQ85|FLT110|Altair DF250RC|EQ6 Pro(Rowan Belt Mod)|ParamountMX
ATIK383L+/EFW2/OAG|Lodestar|Baader 36mm LRGBHaSIIOIII
Starlight Express SXVRH16/ONAG/FW|Lodestar X2|Baader 2" Filters
Starlight Express SXVRH814/ONAG/FW|LodestarX2|Baader 2" Filters
Lunt LS60PTBF1200|DMK41|Quark Chromo
Samyang 135mm f1.8

Offline Roger B

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Re: Tips for a mosaic
« Reply #2 on: 11:57:30, 16 January, 2016 »
cheers Chis,

I have one part in that,  That's is very much 90% unsuccessful & that's the plate solve, 90% of the time it doesn't work for me.    but I'll give it a go.


Rog
Scopes - TS65q, W/O 110 Triplet
Mount - EQ6 PRO via  Eqmod,  Rowan belt modded
Cameras - SX694, QSI583WSG,Lodestar Guidecam, GP-Cam, QHY5II.
TS 9mm OAG
Quantum 7x1.25 EFW, Baader LRGB,Ha,OIII,SII Filters 
Quark chromo

SGPro, Pixinsight.

************AND NO TIME TO USE IT************

Offline chris.bailey

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Re: Tips for a mosaic
« Reply #3 on: 12:06:37, 16 January, 2016 »
Rog

It can be a bit finicky in solving. You do need to seed it with a RA and Dec value somewhere within the image but you should be able to get that from SGPro or Sky6. You done need to be uber accurate with it, degrees and minutes will suffice. You also need to put in the correct date as the DATE-OBS keyword from the .fits header won't be there on a stack.

Chris
LX200|ZS70|FSQ85|FLT110|Altair DF250RC|EQ6 Pro(Rowan Belt Mod)|ParamountMX
ATIK383L+/EFW2/OAG|Lodestar|Baader 36mm LRGBHaSIIOIII
Starlight Express SXVRH16/ONAG/FW|Lodestar X2|Baader 2" Filters
Starlight Express SXVRH814/ONAG/FW|LodestarX2|Baader 2" Filters
Lunt LS60PTBF1200|DMK41|Quark Chromo
Samyang 135mm f1.8

Offline Roger B

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Re: Tips for a mosaic
« Reply #4 on: 12:20:37, 16 January, 2016 »
 :thumbup: :thumbup:

Trying now mate.

Rog
Scopes - TS65q, W/O 110 Triplet
Mount - EQ6 PRO via  Eqmod,  Rowan belt modded
Cameras - SX694, QSI583WSG,Lodestar Guidecam, GP-Cam, QHY5II.
TS 9mm OAG
Quantum 7x1.25 EFW, Baader LRGB,Ha,OIII,SII Filters 
Quark chromo

SGPro, Pixinsight.

************AND NO TIME TO USE IT************

Offline Roger B

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Re: Tips for a mosaic
« Reply #5 on: 12:42:06, 16 January, 2016 »
Rog

4) Use Image Solver in PI to plate solve each frame. This adds WCS co-ordinates to the .fits header.
Chris


Chris,  I take it the same Coordinates are used for all the frames,  you said it doesn't have to super critical but I thought I'd ask.  If not then how would I get the coordinates for each frame as I'll only know them for the objuct.

Rog
Scopes - TS65q, W/O 110 Triplet
Mount - EQ6 PRO via  Eqmod,  Rowan belt modded
Cameras - SX694, QSI583WSG,Lodestar Guidecam, GP-Cam, QHY5II.
TS 9mm OAG
Quantum 7x1.25 EFW, Baader LRGB,Ha,OIII,SII Filters 
Quark chromo

SGPro, Pixinsight.

************AND NO TIME TO USE IT************

Offline Roger B

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Re: Tips for a mosaic
« Reply #6 on: 12:54:56, 16 January, 2016 »
LOL,

I knew it would fail on the solving   

NGC1499 on the 15/1/2016
RA 04:04:19
DEC 36:24:07

I get this error in PI

*** Error: Unable to find an initial set of putative star pair matches
<* failed *>
*** Error: The image could not be aligned with the reference star field
Please check the following items:
The initial coordinates should be inside the image.
The initial resolution should be in a factor of 2 of the correct value.
Adjust the sensitivity so the script detects most of the stars in the image without mistaking noise for stars.
The catalog should be matched to the image. Choose the catalog and magnitude filter so the number ofstars extracted from the catalog is similar to the number of stars detected in the image.
*** The image could not be solved.
This is usually because the initial parameters are too far from the real metadata of the image
Scopes - TS65q, W/O 110 Triplet
Mount - EQ6 PRO via  Eqmod,  Rowan belt modded
Cameras - SX694, QSI583WSG,Lodestar Guidecam, GP-Cam, QHY5II.
TS 9mm OAG
Quantum 7x1.25 EFW, Baader LRGB,Ha,OIII,SII Filters 
Quark chromo

SGPro, Pixinsight.

************AND NO TIME TO USE IT************

Offline Roger B

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Re: Tips for a mosaic
« Reply #7 on: 13:09:12, 16 January, 2016 »
I have managed to Solve 2 of the 3 images but just cannot solve the 1st one.   

Rog
Scopes - TS65q, W/O 110 Triplet
Mount - EQ6 PRO via  Eqmod,  Rowan belt modded
Cameras - SX694, QSI583WSG,Lodestar Guidecam, GP-Cam, QHY5II.
TS 9mm OAG
Quantum 7x1.25 EFW, Baader LRGB,Ha,OIII,SII Filters 
Quark chromo

SGPro, Pixinsight.

************AND NO TIME TO USE IT************

Offline Roger B

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Re: Tips for a mosaic
« Reply #8 on: 13:21:16, 16 January, 2016 »
Damm that was not simple, lol    In the end I got the co-ordinates from a single file.   All 3 now solved I hope. lol


Rog
Scopes - TS65q, W/O 110 Triplet
Mount - EQ6 PRO via  Eqmod,  Rowan belt modded
Cameras - SX694, QSI583WSG,Lodestar Guidecam, GP-Cam, QHY5II.
TS 9mm OAG
Quantum 7x1.25 EFW, Baader LRGB,Ha,OIII,SII Filters 
Quark chromo

SGPro, Pixinsight.

************AND NO TIME TO USE IT************

Offline chris.bailey

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Re: Tips for a mosaic
« Reply #9 on: 13:24:36, 16 January, 2016 »
Rog

A lot will depend on how big an area the mosaic covers. For the veil to solve I had do it in two lumps, one RA/Dec seed for the top and another for the bottom. Things to try

1) Change from PPMXL to UCAC3 as the catalogue.

2) Under Advanced Parameters, try Star Sensitivity of 2.5 and increase noise reduction to 1 or even 2.

3) Check the focal length and pixel size give the right image scale. This needs to be pretty precise.

with a bit of playing around, I have not found an image yet that wont solve.

Chris

LX200|ZS70|FSQ85|FLT110|Altair DF250RC|EQ6 Pro(Rowan Belt Mod)|ParamountMX
ATIK383L+/EFW2/OAG|Lodestar|Baader 36mm LRGBHaSIIOIII
Starlight Express SXVRH16/ONAG/FW|Lodestar X2|Baader 2" Filters
Starlight Express SXVRH814/ONAG/FW|LodestarX2|Baader 2" Filters
Lunt LS60PTBF1200|DMK41|Quark Chromo
Samyang 135mm f1.8

Offline Roger B

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Re: Tips for a mosaic
« Reply #10 on: 13:43:16, 16 January, 2016 »
I've done it but it's awful 

You can see the joins, & where I done a linear fit on the other two images those two frames stand out like a saw thumb,  so I'm wondering if I have read your work flow incorrectly.     

Should I only linear fit if the resulting finished mosaic shows a difference ?       Or are you saying do a linear fit @ step 1a ?

Rog
Scopes - TS65q, W/O 110 Triplet
Mount - EQ6 PRO via  Eqmod,  Rowan belt modded
Cameras - SX694, QSI583WSG,Lodestar Guidecam, GP-Cam, QHY5II.
TS 9mm OAG
Quantum 7x1.25 EFW, Baader LRGB,Ha,OIII,SII Filters 
Quark chromo

SGPro, Pixinsight.

************AND NO TIME TO USE IT************

Offline chris.bailey

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Re: Tips for a mosaic
« Reply #11 on: 14:06:46, 16 January, 2016 »
Rog

Only do 1a IF there is a marked difference in frames from the result of not doing it i.e. only do it if needed. I find if you do DBE on one and not the others it is needed.

Chris

ps is this a mono mosaic or colour?
LX200|ZS70|FSQ85|FLT110|Altair DF250RC|EQ6 Pro(Rowan Belt Mod)|ParamountMX
ATIK383L+/EFW2/OAG|Lodestar|Baader 36mm LRGBHaSIIOIII
Starlight Express SXVRH16/ONAG/FW|Lodestar X2|Baader 2" Filters
Starlight Express SXVRH814/ONAG/FW|LodestarX2|Baader 2" Filters
Lunt LS60PTBF1200|DMK41|Quark Chromo
Samyang 135mm f1.8

Offline Roger B

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Re: Tips for a mosaic
« Reply #12 on: 14:15:02, 16 January, 2016 »
I'll try later,  My brain if cooked at the mo.   

P.S it's mono version

I even tried Harry pages way but I think his tutorial is for only 2 images and not more as I couldn't get it to work with 3 but could with 2,  although you still see the join. 

gonna have a couple of hours off as I've been sitting at the desk for a few hours now & need a break from it. lol....   

Rog
Scopes - TS65q, W/O 110 Triplet
Mount - EQ6 PRO via  Eqmod,  Rowan belt modded
Cameras - SX694, QSI583WSG,Lodestar Guidecam, GP-Cam, QHY5II.
TS 9mm OAG
Quantum 7x1.25 EFW, Baader LRGB,Ha,OIII,SII Filters 
Quark chromo

SGPro, Pixinsight.

************AND NO TIME TO USE IT************

Offline Roger B

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Re: Tips for a mosaic
« Reply #13 on: 21:25:09, 16 January, 2016 »
OH COME ON !!!!!!!

how hard can this bl**dy be....   

Now I can't even get a mosaic !!!!!!   

See images of my 3 separate images before Grad Merge Mosaic,  & then see the next one that gives the output.  WTF am I doing wrong here

Roger
Scopes - TS65q, W/O 110 Triplet
Mount - EQ6 PRO via  Eqmod,  Rowan belt modded
Cameras - SX694, QSI583WSG,Lodestar Guidecam, GP-Cam, QHY5II.
TS 9mm OAG
Quantum 7x1.25 EFW, Baader LRGB,Ha,OIII,SII Filters 
Quark chromo

SGPro, Pixinsight.

************AND NO TIME TO USE IT************

Offline Roger B

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Re: Tips for a mosaic
« Reply #14 on: 21:40:54, 16 January, 2016 »
Damm Damm Damm,

what a complete C*ck I am I have been sitting here for about 90 mins pulling what I have left of hair, just to realise I have missed a step in the processing,  serves me right for writing them down on the last one from today & not completing it all.

I missed   Mosaic by co-ordinates...

roger
Scopes - TS65q, W/O 110 Triplet
Mount - EQ6 PRO via  Eqmod,  Rowan belt modded
Cameras - SX694, QSI583WSG,Lodestar Guidecam, GP-Cam, QHY5II.
TS 9mm OAG
Quantum 7x1.25 EFW, Baader LRGB,Ha,OIII,SII Filters 
Quark chromo

SGPro, Pixinsight.

************AND NO TIME TO USE IT************

 

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