Hi to everybody, I am the creator of Healpix.jl, a Julia package (https://github.com/ziotom78/Healpix.jl) which implements algorithms related to the Healpix sphere tessellation scheme (http://healpix.jpl.nasa.gov/). The Healpix scheme subdivides a sphere in patches (pixels) of equal area, and it is widely used in cosmology. I am writing to julia-user because I would like to implement visualization functions too, but I haven't figured out what is the best way to implement them.
So far, I have used the Healpy (https://github.com/healpy/healpy) library as a reference for my implementation. Healpy wraps the original C++ Healpix library in a Python module. It uses Matplotlib to create plots of spherical projections. Internally, both the original C++ Healpix library and Healpy produce such plots by calculating a bitmapped representation of the projection: they convert each (x,y) point in the image plane into a normalized (u,v) coordinate, which is then spherically projected to a point on the sphere's surface. The value associated to the point on the sphere determines the color of the point at (x,y). Here are a few examples of typical Healpix maps: http://healpix.jpl.nasa.gov/images/skymaps/ecl53s.gif (Mollweide projection), http://healpix.sourceforge.net/html/plot_orthpolrot.png (Orthogonal projection). The algorithm is really easy to implement in Julia, but I cannot decide how to actually do the following: 1. How to interactively show the map by e.g. opening a window, or by displaying the image directly in a IJulia notebook? 2. The bitmap produced using this algorithm associates a scalar to each pixel, but one usually wants to convert such scalar through a color map in order to have a RGB value to be actually drawable. (I am interested in piecewise-linear maps). 3. When displaying the map, how to put a color bar under the map, like in the two links I provided above? I have had a look at ImageView, and it look ok for point 1. However, it seems to me that it is oriented towards "real" image files, because I cannot find support for color maps and color bars. If it is really so, is there any other Julia package which would be relevant for my purposes? Thanks a lot, Maurizio.
