Solar Position Calculator/Map (version 2!)

[iesmith]

<p>Hi,</p>

<p>A while back I posted a link here about a new web application I'd put together at <a href="http://www.iesmith.net/tools/solarcalc.html">http://www.iesmith.net/tools/solarcalc.html</a> to calculate where in the sky the Sun is at sunrise/sunset and at other arbitrary times. I'd done this with photographers in mind primarily, and so the application plotted these positions against a Google Map of the area rather than just raw numbers.</p>

<p>Hope you don't mind me posting the link, but I received some requests here at the time to enable the application to plot Lunar positions (and phase) as well... It's taken a while, but the new features have finally gone live today.</p>

<p>Other new features include magnetic declination calculation, autodetection of location time zones and much improved accuracy.</p>

<p>Obviously it's new, so if you do find any bugs or inaccuracies feel free to point them out. Feature requests are more than welcome also!</p>

<p>thanks,<br>

Iain</p>

[JDMvW]

<p>This sort of thing can be very useful. Here is a link to your earlier post which has other things listed that serve the purpose http://www.photo.net/casual-conversations-forum/00TfEe</p>

[iesmith]

<p>2009! Was it that long ago?! Spare time at the computer is hard to come by... :-(</p>

[MichaelChang]

<p>Hi Iain, nice app., and thanks for posting. </p>

<p>I do have some comments:</p>

<ol>

<li>I would prefer the default zoom level to be tighter in order to better see possible local obstructions.</li>

<li>It'd be great if a [Print] feature was available.</li>

<li>Might be asking too much, but a one-line local weather would be helpful. </li>

<li>Local elevation will be useful too. </li>

</ol>

[JDMvW]

<p>Time flies when you're having fun, they say. :)</p>

[leicaglow]

<p>That's incredible. Thanks!</p>

[tom_mann1]

<p>Superb! Great user interface - it was immediately obvious how to use it! I love the useful side comments like "The Sun is now below the horizon".</p>

<p>I'm not sure how often I'll need info like this , but if I need such info in planning a shoot, I'll certainly use yours.</p>

<p>Thank you.</p>

<p>Tom M</p>

 

[MichaelChang]

<p>The application actually bears a remarkable resemblance with The Photographer's Ephemeris, a desktop app. running with Adobe Air: <br>

<a href="http://photoephemeris.com/">http://photoephemeris.com/</a></p>

[jim_momary]

<p>What a neat thing!<br>

Simply wonderful. Thinking of lighthouses and sunsets now :o)<br>

Jim</p>

[bernard_lazareff]

<p>For a moment I thought this would enable me to become famous with my planned photo "Moonrise over Belledonne". But, alas, your app does not take into account local terrain.<br>

Jokes aside, many kudos! And, given that you compute the elevation, one can use your app in hill terrain.</p>

[iesmith]

<p>In response to Micheal's suggestions:<br /><br />1. I'm still on the fence about this issue to be honest. That said, I do find myself doing the same, so I agree you have a valid point. I'd thought of storing the last used zoom level, but that presents the problem that when searching for a new location there is a tendency to get a bit lost and have to zoom out again. <br /><br />2. Agreed, and an excellent idea. <br /><br />3. I'd actually already looked at implementing weather reporting, but I'm a bit reluctant to add in another XML call to an external server, as I'm worried that too many of these calls will slow the application down unduly. I may add a 'ready-made' hyperlink to a third party weather site, assuming I can find a good one with worldwide coverage that will accept a latitude/longitude query in the URL.<br /><br />4. Again, I already looked at this, and it is already built into the algorithms for both magnetic declination and sun/moon positions. I've disabled it for the moment however, since I'm not convinced by the preliminary results I'm seeing, and have found it difficult to get an independent confirmation of the numbers. If I can find a good reference source that I know for certain accounts for local elevation (anyone know of one?) and I can verify my results with it, I'll re-enable the feature. <br /><br />Yes, it does kind of look like TPE. :-) I guess that's down to the fact that they both use the Google Maps API at their heart, and use similar map overlays to plot sun & moon positions. They are otherwise quite different though, and I've made many different design decisions along the way, such as magnetic declination and graphically illustrated moon phases. TPE is a fantastic tool though, and it's been helpful as one of the sanity checks of my results. I just find a web app more useful to me personally - all down to preference.</p>

<p>Bernard, I would have loved to have been able to account for someone inconsiderately placing a building in what would have otherwise been a perfectly placed sunrise! ;-) Sadly beyond me I suspect, though you have made me wonder what might be possible in Street View...</p>

<p>Thanks for your feedback...</p>

[MichaelChang]

<p>Thank you for the explanation, Iain. </p>

<p>I also prefer a web based application for its convenience. </p>

<p>It's amusing that of any location on the planet available to you as a default location, Chicoutimi was chosen. :-) I was reminded of my visit there some years ago in the dead of winter and how bitterly cold it was. </p>

[mark_sirota1]

<p>Very cool and useful. Two suggestions:<br>

(1) I'd like to have "next day" and "previous day" buttons that would just increment/decrement by 24 hours and recalculate, so I could watch the rays move day by day.</p>

<p>(2) Please use a consistent date format throughout. When entering dates you use DD-MM-YYYY, and displaying them for sunrise/sunset etc. you use DD/MM/YYYY. I would suggest using <a href="https://secure.wikimedia.org/wikipedia/en/wiki/ISO_8601">ISO 8601 standard dates</a> (YYYY-MM-DD) throughout.</p>

[mark_sirota1]

<p>Another suggestion: For the moon, indicate its relative size (small at apogee, large at perigee). Here's a site that calculates it, but you could calculate it yourself.</p>

<p><a href="http://www.fourmilab.ch/earthview/pacalc.html">http://www.fourmilab.ch/earthview/pacalc.html</a></p>

[tom_mann1]

<p>Obviously, the perceived size of the moon changes greatly depending on proximity to the horizon, etc., but as I recall, the difference between lunar apogee and perigee distances is only 12% or so, so the actual angular size would only change by about the same amount. I'm curious -- under what circumstances would such a small difference be important to a photographer?</p>

<p>Tom M</p>

[MichaelChang]

<blockquote>

<p><em>"the perceived size of the moon changes greatly depending on proximity to the horizon, etc."</em></p>

</blockquote>

<p>The "etc." might be atmospheric conditions which can have a greater influence on perceived size at the same proximity to the horizon. </p>

[iesmith]

<p>The angular diameter at apogee versus perigee is only about 5 seconds of arc I think, it probably isn't detectable with the naked eye (or lens).</p>

<p>Atmospheric refraction does tend to play a part close to the horizon, but it's effect is just to squash it slightly in the vertical axis: <a href="http://en.wikipedia.org/wiki/Moon_illusion">http://en.wikipedia.org/wiki/Moon_illusion</a></p>

<p>It might have more of an effect in the amount of light it casts at a full moon, which might have an application for those night-time and astro-photographers, but I honestly wouldn't know as it's not something I've tried.</p>

[iesmith]

<p>Mark,</p>

<p>In response:<br>

1. Good idea, I'll see what I can do. Shouldn't be tough to implement.<br>

2. Well spotted, I'd missed that entirely!</p>

<p>Micheal,<br>

It actually picks it's default location based on a GeoIP (<a href="http://www.maxmind.com/">http://www.maxmind.com/</a>) database. It works well a fair percentage of the time, but when it gets it wrong, it gets it very wrong, as I gather it did in the case of Chicoutimi!</p>

<p>I was thinging of including an option to turn it off actually... It creeps me out a little bit how accurate it is for my home computer!</p>