aligning Ganymede in image with Jup and Io

[Muddy Diver]

Can anyone offer me some advice please?

I recorded 800 frames of Jupiter with Io and Europa and then more of Jupiter IO and Ganymede this morning. The idea is to extract the Ganymede image and add it to a BMP which already contains Europa, Jup and Io recorded oin the same session. My plan to put them all together in one BMP

I cant use PPMcentre as it centres Jupiter and drops Ganymede out of frame Q1, can I increase the height in ppmcentre to a higher value than my reborded AVI to counteract this? My AVI is 640w X480h.

so straight into Registax with my AVI,tracking and misalign warning functions on and align. After limiting the stack size I get an INvalid floating point warning and Registax freezes up.

Does anyone have any suggestions apart from the obvious one that I should have known this was going to happen and shot Ganymede on its own. Ahh Hindsight! I really dont want to manually align all the frames only to find that I hit the same problem.



I've attached a frame to explain the predicament. Forget the over exposed jupiter, I didnt want that for this shot.

[bird (Anthony Wesley)]

Hi Muddy. By default ppmcentre cuts out the centre 400x400 section of the source frame, but you can change that with the -cutx and -cuty parameters. Also you can change the size of the output image with the -width and -height parameters.

There is also the shorthand "-cut" which sets all four of these switches to the same value, so if you wanted to cut out a 500x500 area and set the output frame size also to 500x500 then you can just say -cut=500.

You should have a read of the other switches and options on the website:

www.acquerra.com.au/astro/software/ppmcentre/

cheers, Bird

[Muddy Diver]

Thanks Bird.

I've now managed to get the attachment up so it is a little clearer to explain. You see, because of the distance Ganymede is from Jupiter, and the fact that PPM Centre will always pick the most obvious target (in this case Jupiter) to centre, then Ganymede is always going to be out of frame.This frame original sixe is 480 high which means that as Jupiter is at the top, worse case scenario is that it will drop around 200 and so will ganymede. as Ganymede is already towards the bottom of the original frame I estimate that the overall height would need to be in excess of 560 which is greater than my original size. If only I could select what ppmcentre uses to centre I would be making progress. Is there a way of cropping th top of my frames as an AVI perhaps. Get rid of Jupiter and Io and my troubles are over. Does anyone have a suggestion?, I don't know of any way to do this

[bird (Anthony Wesley)]

Yes, there's an assumption in ppmcentre that the output frames will not be any larger than the input frames... I'll see if I can fix that and post a new version, that ought to solve your problem.

cheers, Bird

[Muddy Diver]

ER... yup, I guess it would. Sorry, I didnt realise you are the ppmcentre developer Bird. Wow, what a great response!

I don't want you to go to any trouble if it isnt what others would want though.