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  • Akarsh Simha 10:08 am on January 30, 2008 Permalink  

    Minor patch: Bringing labels closer 

    When I looked at a freshly compiled version of KStars after a long time, and zoomed in on M31, the label that read ‘M31’ was far, far away from the Galaxy, as if it were labeling the empty sky! (The separation was about 2 degrees between the left top corner of the label and the center of M31) Same was the case with M33 – this time the labeling was 50 arcminutes away.
    After some tinkering around, it was pretty obvious that the offset of the label was calculated by taking the major axis of the object and scaling it by various zoom factors and adding an additional constant displacement. Now, the correct solution is to find out the actual distance of the bottom left portion of the object’s boundary from the center, so that the label is just placed outside the object to it’s bottom left. I didn’t know how to calculate that, because I don’t know the angle at which the major axis of the ellipse / rectangle is inclined. So I tried changing the computation to take the average of the major and minor axes. Now it looks a little more decent, but as is expected, there are times when the label comes too close (or maybe penetrates into) the object boundary!
    Anybody willing to do a better computation should help KStars by letting the devel mailing list know!
    The patch is on SVN commit #768419 to the Trunk. I know it is really a dumb patch, but makes things look better.

    Here’s a copy of the patch:

    — trunk/KDE/kdeedu/kstars/kstars/deepskyobject.cpp #768418:768419
    @@ -328,8 +328,12 @@
    double DeepSkyObject::labelOffset() const {
    //Calculate object size in pixels
    double majorAxis = a();

    • if ( majorAxis == 0.0 && type() == 1 ) majorAxis = 1.0; //catalog stars

    + double minorAxis = b();
    + if ( majorAxis == 0.0 && type() == 1 ) { //catalog stars
    + majorAxis = 1.0;
    + minorAxis = 1.0;
    + }
    double scale = SkyMap::Instance()->scale();

    • double size = majorAxis * scale * dms::PI * Options::zoomFactor()/10800.0;

    + double size = ((majorAxis + minorAxis) / 2.0 ) * scale * dms::PI * Options::zoomFactor()/10800.0;
    return 0.5*size + 4.;
    }

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  • Akarsh Simha 11:47 am on January 28, 2008 Permalink
    Tags: , Classical Nite, Saarang   

    Concert by VVS, Saarang 2008 Classical Nite. 

    (23rd Jan 2008)

    This time, Saarang 2008’s classical nite was a concert by Violin Maestro Prof. V. V. Subramaniam accompanied by his son and disciple Sri V V S Murari on the Violin, Sri Tiruvarur M Bhaktavatsalam on the mRdaNgam, and Vykom Sri Gopalakrishnan on the ghaTam.

    Prof VVS initially played light songs like vAtApi (hamsadhwani), parAtpara (vAcaspati). On of the best pieces was janani ninnuvinA in rItigauLe. The main piece, SrI vaLLi dEvasenApatE in naTabhairavi was excellent. The taniyAvartanam was very good, needless to say.

    There was a nice kRti in bEhAg followed by a KavaLi cindu and finally a sindhubhairavi kRti.

    It was nice to listen to a concert at the OAT!

     
  • Akarsh Simha 11:37 am on January 28, 2008 Permalink
    Tags: , camstream, , Philips ToUcam, streamer, Webcam   

    Photographing Saturn on Linux! 

    We used my friend Dr. Suresh’s Philips ToUcam webcam with minor modifications to photograph Saturn through our institute’s 8″ Celestron GT Advanced telescope!
    A bit of googling told me how to use a Webcam with Linux – there’s the Linux Webcam HOWTO that has more than you’ll ever need.
    The kernel happened to be very nice and detected the webcam and provided a /dev/video0 device – so I didn’t have to break my head over that. A bit of software that was available on the Debian repositories called ‘camstream’ helped me view the webcam image and take snapshots at 1 fps (which is rather slow 😦 ). The Webcam HOWTO also talked of this CLI program called ‘streamer’ (this was on the Debian repos as well) which could capture from the webcam in AVI format!
    My friend and me processed the photos using Registax v4 (No! this is not Open Source X-( ) on WINE and then with The GIMP. Registax is not open source and is rather limited in functionality – it can’t handle more than 500 still image files at a time, couldn’t read the AVI format we captured in, and most importantly doesn’t run natively on Linux. This has inspired us to think of writing a FOSS stacking software. I have no idea how we’ll do that because nobody knows anything about stacking here! If somebody is interested in helping out, please drop a comment or contact me on IRC etc etc.
    Our photos are available here:
    http://www.bas.org.in/Home/index.php?q=gallery&g2_itemId=1136
    And as is expected of true open source fanatics, we release them to Public Domain. No rights reserved 🙂

     
    • Anirudh 11:58 pm on February 18, 2008 Permalink | Log in to Reply

      Your fps problem can be solved to an extent.Lookup this page http://opencvlibrary.sourceforge.net/CameraCapture .I got a fps of about 8 using this and a logitech webcam.

    • Akarsh Simha 11:27 am on February 19, 2008 Permalink | Log in to Reply

      Thanks Anirudh. I’ll take a look at it.
      Streamer can do 10 fps with the Philips ToUcam, but I don’t know how to adjust exposure etc with streamer, and I don’t think it can.
      I’ll see if CameraCapture can do this.

    • Kernowyon 1:38 am on April 24, 2008 Permalink | Log in to Reply

      Hi,
      wxcam, which was designed partly with astrophotography in mind I believe, gives 10 fps @ 640×480. Tested using a Celestron Neximage cam – which is basically the ToUcam in a new body.
      I have messed around with some older CMOS based cams but they don’t have the sensitivity at night. But they did let me check that wxcam would give a reasonable framerate. I got similar framerates from a Logitech cam, but with lower resolution.
      If you are using one of the Ubuntu based systems, then there is a .deb which installs easily.

    • Akarsh Simha 2:11 am on April 27, 2008 Permalink | Log in to Reply

      Thanks for the info Kernowyon. I’ll try it next time I get a webcam in hand.

    • Mercurio 9:51 pm on June 18, 2008 Permalink | Log in to Reply

      Hi,
      I was looking for a FOSS software for staking images too.

      Maybe Hugin can do it, even if its purpose is different 🙂
      http://wiki.panotools.org/Align_image_stack

    • Akarsh Simha 11:20 am on June 22, 2008 Permalink | Log in to Reply

      I took a brief look at the Hugin Wiki. It sounds pretty attractive, for photography in general and astrophotography as well. (Imagine putting together a Milky Way panorama or something 😀 some day). Thanks a lot for pointing me there. I’ll take some time out this week and get Hugin installed.

  • Akarsh Simha 11:28 am on January 28, 2008 Permalink  

    Compiling KDE from SVN sources… 

    …is a major pain.

    I encountered quite some trouble and still amn’t through.
    It looks like a spotted a bug http://bugs.kde.org/show_bug.cgi?id=156791 with the detection of Xine libs in Revision 767273 (I guess) on the way, and while I wait for feedback on the bug, I decided to compile without Multimedia support.

    We work behind a HTTP Proxy in our institute, which does not permit “svn://…” URLs. So I end up having to torify all SVN checkouts and updates, which makes life even more miserable because the way tor works, it ends up taking ages to transfer even small amounts of data – and the connection keeps cutting off. It’s like downloading KDE4 sources with a dialup connection!

    Even as I type this post, I have a torify svn co running in the background. I’m trying to look for help on how we can get the proxy to permit SVN. If anyone knows how to do this, please do leave a comment, and we’ll see if we can request the Computer Center here to implement such a feature.

     
    • harshadrj 11:42 am on February 1, 2008 Permalink | Log in to Reply

      it’s not the proxy server that you should be looking at..

      rather the firewall which sits between your CC and the net, should have the svn port enabled.

      However, AFAIK, svn supports http as it’s transport protocol. You should be able to change
      svn co svn://
      to
      svn co http+svn://

      provided KDE has enabled http, which I am sure they have..

    • akarshsimha 2:06 pm on February 1, 2008 Permalink | Log in to Reply

      [10:kstar@PENGUIN$ svntest]$ svn co http+svn://anonsvn.kde.org/home/kde/trunk/KDE/kdeedu/kstars
      svn: PROPFIND request failed on ‘/home/kde/trunk/KDE/kdeedu/kstars’
      svn: PROPFIND of ‘/home/kde/trunk/KDE/kdeedu/kstars’: 400 Bad Request (http+svn://anonsvn.kde.org:0)


      Nopes. Looks like it didn’t work!

    • harshad 5:37 pm on February 2, 2008 Permalink | Log in to Reply

      hmm.. you are out of luck! KDE seems to have enabled “http + SVN” only for developers. Anonymous checkout only works for “SVN”. See,
      http://wiki.kde.org/tiki-index.php?page=KDE+Subversion+HOWTO

      Anyway, the http version of the command should actually look like:
      svn co https://anonsvn.blahblah

      (if they do enable it for anonsvn)

    • akarshsimha 6:42 pm on February 2, 2008 Permalink | Log in to Reply

      Yes… I guess I’ve seen that. https is also enabled only for the developers!

    • Shashank Singh 7:51 pm on May 14, 2008 Permalink | Log in to Reply

      even in my University SVN+SSH is blocked ,, so i use to use proxy softwares like jap (or your freedom) to access anon svn , but when i got a developers account from kde , the https +svn has been working smoothly fro me 🙂 ..

    • Akarsh Simha 3:13 am on May 15, 2008 Permalink | Log in to Reply

      Finally, NAT was enabled in our institute about two months ago, and we requested for the SVN port to be opened. The Computer Center was very kind in opening the port. So now I can do checkouts from the anonsvn without any trouble at all.

      I haven’t heard of either jap or your freedom. Thanks for the pointers, I’ll take a look at them. I used to use torify before the port was opened. Anyway, checkouts are faster through NAT because NAT is allocated separate bandwidth and number of users are very few.

  • Akarsh Simha 11:17 am on January 28, 2008 Permalink
    Tags:   

    Yet another concert… 

    Yes, a blog post after long time.

    This time I attended Sangeeta Kalanidhi Prof. T. N. Krishnan’s concert at Hamsadhwani in Indira Nagar on 26th Jan 2008, Republic Day.

    He started with Vatapi Ganapathim (Hamsadhwani, M. Deekshitar) as a tribute to Founder Secretary of Hamsadhwani who organized the concert. This was followed by some krtis in kAMbODhi and dhanyAsi, which I am unfamiliar with. The Main piece was nannu pAlimpa (mOhanam, tyAgarAjar). The main piece was followed by various songs to mark the occasion of Republic Day like raghupati rAghava rAjA rAm, vandE mAtaram (dES) and vaiSNo-something (behAg).

    Prof T N Krishnan was accompanied by his daughter and disciple Smt. Viji Krishnan Natarajan on the violin, by Thiruvarur M Bhaktavatsalam on the mRdaNgam, and by Vykom Sri Gopalakrishnan on the Ghatam. Needless to say, the taniyAvartanam was marvellous.

    The acoustics at Hamsadhwani was the major turnoff.

     
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