Changes between Initial Version and Version 1 of Ticket #1808

Sep 10, 2007, 8:41:00 AM (16 years ago)

Trim out unrelated flipping issue.

Denis, would you be in a position to review and apply the driver changes? If not, I can turn it over to Mateusz though he has little experience with the esoteric world of netcdf as far as I know.


  • Ticket #1808 – Description

    initial v1  
    8080the code base I would be delighted. If you don't I'll live with that and
    8181just maintain the extensions I need privately.
    83 There is one issue that disturbs me though. I found an issue with the
    84 current driver code whereby if you have a data set in which the top y
    85 coord value is less than the bottom y coord value the image gets
    86 flipped. It's hard to explain but it happens with a very useful
    87 bathymetry file we have at CSIRO. With the old driver no matter what I
    88 did there is no way I could get the image coming up the right way. It's
    89 a long time since I looked into that issue so my recollection of the
    90 reason is not clear but there are comments in the code describing it.
    92         //Here we have arranged the transformation such that the maximum
    93         //y values are always top and the scale is always negative.
    94         //Stictly speaking this is clearly not necessary although I am
    95         //doing it this because I need to, as images of that type end up
    96         //being flipped for some reason that I'm unsure of.
    97         double dOrigin;
    98                 .
    99                 .
    102 The reason why I'm mentioning it to you is that my gut feeling is that
    103 the real source of the problem lies elsewhere but I don't understand the
    104 code well enough (and don't have the time to learn it in detail) to be
    105 able to fix it in the right place. The fix I wrote seems to work without
    106 side effect, and I did the re-write to the latest code base such that it
    107 does not utilise my fix if opening in the old way, only when you add
    108 extra parameters to the filename. Therefore, it should be safe for
    109 existing users. If you happen to figure out the "real" reason why this
    110 happens and the "best" fix then I'd be truly greatful.
    112 Regards,
    114 Paavo.