Mosaic wizard not creating 2x2 mosaics


#1

Hi

I’m probably doing something stupid, but thought I’d ask anyway.

I am trialing the mosaic wizard and it’s really nice. Except I have one problem.

If I set it up to do a 1x3 mosaic for instance (1 row high), everything works fine.
If I set it to do a 2x3 (or anything more than 1 high), it misses out big chunks between the rows.

I’ve tried this a few times now and got the same results.

I’m using an AstroTech AT65EDQ on an Orion Atlas with EQMOD. 1 Star Align so that Platesolve works ok (most of the time).

I’ve solved one of my images and my pixel scale is correct. I also have an overlap of 15% set in the wizard.

Any hints would be great.

Thank you

David


#2

David,
It’s likely that the rotation angle of the mosaic you’ve specified and the rotation angle of your camera are not the same. When creating a mosaic you need to either:

  • Get the angle of your camera and set the Framing and Mosaic Wizard to that angle
  • Rotate your camera to match the angle that you’ve set in the Framing and Mosaic Wizard.

Either will work and it just depends on if you want your camera angle to dictate the framing or if you want to more accurately specify the framing. You can use the “Manual Rotator” device in SGP to aid you in rotating your camera with the plate solver. You can get pretty accurate results within a couple of tries.

The larger the mosaic the more accurate your rotation needs to be. With a 2x2 you probably need to be within a 1-3 degrees of rotation depending on what your field of view is. You can also fudge this by using a larger overlap. But you may need significantly more (25%ish) to account for really bad rotation and that may not be adequate for all situations.

This is just a guess though, if you want more accurate info we’ll need logs and a screenshot of the stitched mosaic would also be helpful.

Hope that helps,
Jared


#3

Hi Jared,

Thanks for the detailed response.

When you say ‘Get the angle of your camera’, do you mean that after I slew to the target I need to see the angle of my camera and then create the mosaic, inputting the angle of the camera? In park position the camera is set to be a rectangle level with the horizon, but I’m guessing the slew rotates it to another angle.

Last night I tried creating a mosaic and rotating the image in the wizard to the rotation that I see in the sky (I’m in the south, so the mosaics downloaded images are generally upside down). But the results turned out to be worse than they were before.

This is a link to the (large) log file.
https://drive.google.com/open?id=0B4mA-LCg94BBc2UzNDBYU0VEUVE

And my rather crazy looking plan.
https://drive.google.com/open?id=0B4mA-LCg94BBdW1pWnl2V0hqbnM

This is the result I get.
https://drive.google.com/open?id=0B4mA-LCg94BBVnhrTDRFQW91VkE
The horsehead part was actually flipped the opposite direction.
I’m guessing the staggered images mean the angle is completely wrong?

I have a feeling I’m asking too much from what I have or I’m just doing something silly.

Thanks for your help

David


#4

Hi again

I tried again last night and had a bit more success, but not perfect.

Process.

  • Took an image of M42 from the night before.
  • Opened the mosaic wizard
  • Rotated the wizard so that the fetched image was the same angle as in my image from the night before.
  • Setup a 3x3 mosaic of M42/Horsehead

The result is this image:
https://drive.google.com/open?id=0B4mA-LCg94BBQkxlMEJhZW9pY1U

It seems to have stitched 6 of the 9 images.
Will I need to manually rotate the camera at the start of each mosaic?

Thanks

David


#5

@David_Williams

Yes. Image angle is of the utmost importance when capturing mosaics, but SGPro can make this pretty easy for you. Have you used the manual rotator tool to help with this? More info here:

http://www.mainsequencesoftware.com/Content/SGPHelp/ManualRotator.html
http://www.mainsequencesoftware.com/Content/SGPHelp/AutomaticCameraRotation.html


#6

Hi Ken,

Thanks for the info. I haven’t tried the Manual Rotator, but will definitely take a look.

Cheers

David


#7

Hi,

Just to let you know that the Manual Rotator solved the problem. Last night I managed to do a 4 panel mosaic by using the Manual Rotator on the first tile. Platesolving, meridian flips and autoguiding all worked perfectly.

Cheers

David


www.mainsequencesoftware.com