[Qgis-user] [QGIS-Developer] Earth, Sun, Moon & Planets Plugin

[C Hamilton]

Tim,

Thanks for the suggestions. I will look into the temporal controller.

As you know I like having the plugins self contained so that they run
immediately. I have struggled with this issue in this case because there
are no astronomical libraries that I can do this with, at least ones that
are highly accurate and use ephemeris data rather than less accurate,
simplified mathematical equations. I try to go for accuracy.

For testing I will release a self contained windows version, but other
users will need to pip install skyfield. In the case of the Date/Time Tools
plugin I made it self contained so that the user didn't need to pip install
anything, but that is what made it so large. It is reasonable for the user
to download the ephemeris data separately. I may be able to extract a small
set of the data that is within the 10 mb limit so that it is shipped with
the plugin so that it works immediately. It just won't have a large date
span, but if they are having to pip install skyfield, it is not going to be
any more difficult to download the ephemeris data.

I think it would be good for QGIS to have some astronomical libraries
included. I've already had people express interest in this capability, but
we will see how much overall interest there is in this plugin. It will get
more acceptance if people do not need to pip install anything.

Astropy is the most active and complex astronomy library. I chose not to
use it because I didn't think it was needed for QGIS. I used Skyfield
instead. It has the necessary functionality that I think is needed for QGIS
projects. It is a modernized version of PyEphem by the same author and is
recommended by the author over PyEphem.

Thanks for your continued support,

Calvin

On Sat, Jun 5, 2021 at 1:04 PM Tim Sutton <tim at kartoza.com> wrote:

> Hi
>
> Wow that looks beautiful! A couple of thoughts:
>
> 1) Rather than implementing your own slider logic I wonder if you could
> hook in to the temporal controller?
> 2) For platform specific components the normal practice is to a)
> communicate with the plugins reviewers about why this is needed so that
> they don't pre-emptively reject your plugin and b) normally pull down the
> platform specific components as a post install step. I expect you will get
> some resistance to adding a new dependency to QGIS core unless that
> dependency is broadly useful, but you may be able to convince Jurgen and
> Peter to bundle it into the Windows and macOS installers respectively.
> 3) For that 100mb blob, similar to our discussion on the timezone work you
> were doing, the preferred approach would be to fetch it as a post-install
> download the first time you use the plugin.
>
> Thanks for making such interesting plugins!
>
> Regards
>
> Tim
>
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