Star Generator

[esraguin]

Please excuse my ignorance but what does Star Generator actually do, tried to look for info on it but must be looking in the wrong place.

Alex

[Astrocava]

Check this:

http://pixinsight.com/forum/index.php?topic=1588.0

Have fun!

Sergio

[Niall Saunders]

Hi Alex,

Fundamentally, StarGenerator is very much like CartesDuCiel - from a given 'centre point' (based on RA, Dec and Epoch information that the user supplies), and a given 'image size', it then goes and looks up a star catalogue. It determines all the stars from that catalogue that would fall 'inside' the boundary edges of the image, and works out the X and Y position of each of those stars in the image. From the 'magnitude' information for each star, and having been informed of the optical behaviour of your 'synthetic telescope' it determines a 'star size' and 'FWHM shape' for each star - and then it 'creates' a synthetic star image for each star that needs to be displayed.

Unlike CdC, it makes no attempt to display anything other than stars.

Currently StarGenerator can only access one particular star catalogue, which is 242Mb in size, and which you have to download to your PC for use by the SG process.

Once you have created your 'synthetic star image' you can use it as a 'reference image' for any star-alignment routine. It has particular benefit to those who may be trying to build large mosaics. After all, the star catalogue already knows where the stars in an image OUGHT to be - so it then becomes a relatively trivial matter for PI to take your multiple mosaic panels and 'stitch' them onto the 'blank canvas' in exactly the correct place, squeezing, twisting and stretching them as needed to get them to fit.

I have now completed my first video tutorial on how to create a simple 'synthetic star image', and am currently busy editing the follow-up video showing how a 'real' image can be aligned to the synthetic image.

As soon as I can find somewhere to 'post' these tutorials, they will be available for everyone to download (Carlos, Juan, Harry )

Cheers,

[esraguin]

Someone told me that certain images are like painting with crayons, When do you draw the line between a real image from a camera and a constructed one, me and my humble astro gear still wants to get the best out of what im capturing, :cheesy:It was said once that the camera does not lie :: Star Generator will no doubt be a wonderful tool when i see its proper use.

Alex

[Niall Saunders]

Hi Alex,

You are missing a key point here - StarGenerator does NOTHING to improve either the content, or the quality of your image.

It's primary aim was to provide a means of getting multiple images, taken as part of a mosaic, to line up with each other without having to manually stretch and twist each image to get it to match with its neighbour.

Of course, you can use it as an 'alignment template' for the image that you are working on - so that you end up with an image that appears 'North Up' for example, and would therefore be capable of being imported straight into CdC, lining up perfectly with the CdC 'stars' in the process.

There is no immediate need for you to understand the SG process - don't worry, you are not missing out on anything. As I said, SG is absolutely NOT necessary for most PI users - until they want to construct a reasonably large mosaic - like you would have to do for the Veil Nebula, given that you only have a DSI-IIC (with a very small chip size) and are confined to imaging through an 8" SCT (even though you have a x0.8 FR in place). Mind you, given our weather here in Aberdeen, that would be a lifetime of dedication to acquire enough raw data for THAT mosaic !!! (My calculations suggest that the mosaic would need to be based on a panel of images 5 wide by 7 tall, i.e. 35 panels. Even at one panel per (decent) night, with our weather that would be 35 night's imaging, or about THREE YEARS  - so you'd better start getting a path dug through the snow to the observatories)

Cheers,