Stellarium

[Ian Pegler]

This is the new thread about Stellarium, a free piece of astronomy software which gives you a photo-realistic view of the night sky for any period in history (or the future) and which even allows you to use your own customised landscapes as a back-drop to the astronomical goings on...

CLICK HERE for the official website

I have been experimenting with creating my own landscapes and, with some difficulty managed to create a "spherical" landscape of where I live, as a practice run for when I go out there and do it for real at some stone circle or another.

Using a fisheye lens on your camera would, I imagine, make the whole process a whole lot simpler. Unfortunately my Sony cybershot is not that sophisticated!

Creating the 360 panoramic image involved using another piece of free software called Hugin to stitch all of my photos (all 47 of them) into a continuous panorama.

CLICK HERE for the official Hugin website.

Having struggled for hours to do that, the next step was to touch the thing up using an image editor. A good free one is The Gimp.

CLICK HERE for the official Gimp website.

The final image size should be in powers of two e.g. 2048 x 1024.

To do this you need to shrink it down to the required width (2048 pixels) whilst keeping the height in proportion. Then begin a new image with the dimensions 2048 x 1024, then copy-paste it across and shunt everything around so that East is on the left hand side of the image. Paste the same image across again and move it until the two are side-by-side and joined up.

You need to make the sky transparent so that Stellarium knows which part of the image it should render the Sun, Moon & planets on.

I now appreciate the effort that goes into these things, it took me days, just to do a rough-and-ready version, but it's quite fun when you see the results...

Ian

[Grahame]

Wow Ian, I'm very impressed that you've managed that so quickly! I really must get one done for Glasgow (currently I use the one for Calton Hill in Edinburgh). There's a nice little modern stone circle in Sighthill constructed back in the '70's by local stronomer and SF writer Duncan Lunan that will be perfect for the job. The council are even kindly demolishing some neighbouring tower blocks this month which will improve the view immensely!

Supplemental - I just installed the Woodhenge landscape and was rather astonished to find what looks like a dowser with L-rods in the picture!



How cool is that?

[Ian Pegler]

Wow Ian, I'm very impressed that you've managed that so quickly!

It was a bit of a rough-and-ready job, but the most difficult bit is getting rid of all the sky to make it transparent. You will notice that in the Woodhenge example, on the sky-line there is a bit of "mist" - this is the bit where the sky from the original image has not been made transparent. It's a pain with things like trees.

Supplemental - I just installed the Woodhenge landscape and was rather astonished to find what looks like a dowser with L-rods in the picture!



How cool is that?

I can see a potential window for subliminal advertising...

Or even comedy...

Ian

[Helen-Healing]

I just installed the Woodhenge landscape and was rather astonished to find what looks like a dowser with L-rods in the picture!

When you enlarge that pic, there's a mysterious white angular line at the top - what is that?

[Grahame]

When you enlarge that pic, there's a mysterious white angular line at the top - what is that?

It's part of a constellation outline, Helen.

[Ian Pegler]

I can see a potential window for subliminal advertising...

Maybe we could do one at Avebury with one or two dowsers in the background, and then put http://www.britishdowsers.org down the bottom, and distribute it for free ?!

Ian

[Grahame]

Brilliant idea, Ian. Now who do we know who lives near Avebury and has a camera.....?

[Ian Pegler]

I've managed to successfully created a landscape of Mitchell's Fold stone circle in Shropshire. This was not easy to do but worthwhile for the experience. Using a tripod is vital as not using one can cause "parallax errors". You need to position it so that it is at the centre and will pivot around on its axis with ease. Obviously the more solid the tripod the better. Also, if the Sun is too strong, you can end up with back-lit images and strong shadows, so you don't want it to be too sunny. You need to eliminate moving things like birds, sheep, cars etc. as much as possible, and make sure that there is an overlap between one photo and the next - this is true for photos in the vertical as well as horizontal planes. I would be tempted to use a slightly wide-angle lens, to make sure of that. You also need to have a strip of sky going all the way around the 360 panorama (although ultimately you make the sky transparent so that Stellarium can work its magic).

I wish had taken more shots, and more of the area below the horizon. What I've ended up with is a strip of the horizon which is long and doesn't really have enough foreground underneath it. But it works, although there's a large amount of black underneath it, where the foreground should be.

It took several attempts to line up the image in such a way that East really corresponds to East in the image. Basically, East needs to be on the left as you view the final thing, which must be 1024 x 512 pixels, or 2048 x 1024. But you don't need to worry about that until towards the end !!!

I would say to anyone wishing to try this out, get some serious practice in before going off on long jaunts to Avebury or anywhere else...

cheers

Ian


Edited by I.P. 7.3.09 - corrected typo

[Ian Pegler]

Stellarium 0.10.0 has just been released !!

Stellarium website

Unfortunately I haven't got broadband !!

Aaaargh!!!

Ian

[Ian Pegler]

Stonehenge is now available as a landscape for Stellarium.

CLICK HERE for this and more landscapes.

Ian

[Grahame]

I just installed v10 and it looks pretty good. The main visible change is that the toolbar is now a pop-up, which leaves the viewing window much 'cleaner'; but there are lots of less obvious changes too.
I've also installed the Stonehenge landscape. I need to play with it a bit more, but to me it looks like the camera is not in the right place to view either midwinter or midsummer sunrise correctly. You can't see through the trilithons to the Heel stone.
It looks pretty, but is not very practical for any archaeoastronomy work.

[Grahame]

Hugo Jenks, who did the Woodhenge landscape for Stellarium, has released a new one for Stonehenge, which is better aligned than the other version. Midsummer sunrise now works - hurrah!

The main site also says that they are working on releasing a version that uses dynamically linked sky content, rather like Google Earth. Ian, I think it's time to consider getting broadband!

[Ian Pegler]

Hi Grahame

I am still experimenting with version 0.10.0 of Stellarium.

I installed this latest Stonehenge landscape as per usual, but I can't get it to work. For some reason it doesn't like the PNG image and all I see is grey. The image is 4096 x 2048 pixels and I have no problems opening it using other packages. My guess is that it doesn't like the size.

Any thoughts?

Ian

[Grahame]

I don't know if this is relevant Ian, but I couldn't get mine to work until I deleted the older version of Stonehenge. Even though I renamed the folder to 'stonehenge_old', Stellarium still insisted that it was there and would open the old version. It didn't even register the new version until I'd deleted the old one.
I have no problems with the image size.

[Ian Pegler]

Hi Grahame

I resolved my problem by using an image editing package to scale the image down to 2048 x 1024.

I still don't know why I should need to do this.

However, I have another problem with this new beta release of Stellarium. Firstly, there doesn't seem to be a way to pause time, at least not an obvious one. This only a minor niggle. The big problem is that when I open the date/time window and try entering an historic date/time it occasionally crashes so badly that I have to turn off the machine. Not even CTRL+ALT+DEL works, I have to turn everything off at the switch. Anyone else noticed this?

cheers

Ian