[Kstars-devel] KStars for astrophotography

[Akarsh Simha]

On Mon, Oct 22, 2012 at 06:11:55PM +0400, Alexey Khudyakov wrote:
> On 22.10.2012 13:19, Jasem Mutlaq wrote:
> >Hello all,
> >
> >I'd like to discuss a few ideas that emerged as I'm using KStars more
> >and more for astrophotography:
> >
> >1. Rotation of skymap: it would be great if I can rotate the whole
> >skymap. Currently, north is "up", but during imaging, it could be
> >different. For example, I just took an image of M33 a few days ago,
> >and in the CCD image, north was "left". So it would be great to orient
> >KStars to match what I'm seeing in the image. I already added a
> >feature to FOV to support the CCD chip orientation, but we need to
> >somehow enable to user to rotate the whole skymap. How difficult is
> >that?
> >
> Another useful feature could be mirrored view.
> 
> It's not easy feature in current state of program. Coordinate
> transformations are difficult in polar coordinates.
> There were discussion about sky point representations and quaternions.
> That representation makes it doable but require complete overhaul of KStars.

Hi

Yes, I agree that we really need both rotation and mirrored view.

I thought it might be easy to implement if we rewrote the projector
base class to also perform some sort of a coordinate rotation. Not
sure if it would be the most efficient way.

I agree that coordinate rotations in polar coordinates are a pain,
unless we use quaternions. I agree it would be best to move into
quaternions, but like Alexey points out, that's a rewrite of large
chunks of code.

The other option is that we could change it at the pixmap level -- we
could render on an appropriately sized pixmap "normally", and then
rotate the pixmap -- but then that would really mess up inverse
functions like fromScreen() and some other features that use the
projector class. I wonder if Qt lets you do something whacky like
rotate a graphics view, so that the model behind still uses the same
coordinate system -- so mouse clicks are mapped back automatically by
Qt.

Regards
Akarsh