Constellations Part 2

By
Dave
Project
Published
20 May 2012 23:45
Last Modified
22 May 2012 19:37

In part 1 I discussed adding support for drawing constellations, boundaries and asterisms, along with their names.

I've now added support for constellation art. Rather than loading individual images for each constellation shown in the camera view, I opted instead to use the same rendering approach as for background filters, which gives on-demand loading at the appropriate level-of-detail. A screenshot is shown below in Figure 1.

Constellation Art

Figure 1. Constellation art. The field-of-view is 70°.

The Space Telescope Science Institiute worked with the U.S. Naval Observatory's Library to scan and painstakingly re-touch a set of beautiful engravings from the 17th century Firmamentum Sobiescianum sive Uranographia star atlas by Johannes Hevelius1. In order to use these images, I first needed to align them with the background stars, then re-project them to a suitable format. I opted for an equirectangular projection. Whilst there is almost certainly a choice of tools available for the job, I thought it would be fun to write my own. The result of applying it to Figure 2 is shown in Figure 3 below.


Ursa Major

Figure 2. Engraving of Ursa Major, "Firmamentum Sobiescianum sive Uranographia", Johannes Hevelius, 16901, positioned appropriately over an spherical, equatorial grid of right-ascension and declination.


Ursa Major

Figure 3. Equirectangular, planar re-projection of Figure 2, resulting in vertical and horizontal lines of right-ascension and declination respectively.

The app will ship with low-res versions of the art, with higher-resolution versions available as an extra. It is, of course possible to use alternative art using the same extensibility model.

1 Image credit the U.S. Naval Observatory and the Space Telescope Science Institute.

Comments

By
mesamundi
22 May 2012 21:31
This is amazing. I love the new art assert insert. The application is really starting to shine. I was already impressed, however your recent graphical updates have moved me solidly into the awed and amazed category.
By
Dave
25 May 2012 20:35
Thanks Mesamundi :) It's taken a while to get the fundamentals in place so that I can move onto shiny stuff!

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