Sun Seeker – Finding a Window’s Sunlight Exposure

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This article explains how you can use the Sun Seeker iOS app to get valuable information about a property’s sunlight exposure by using the app on-site.

Whether you are interested in your existing home or office’s solar exposure, or wanting to understand more about the sunlight availability and exposure of a property you are thinking of renting, buying or moving into, you can easily assess each room or window of interest using Sun Seeker, by following these steps.

Firstly, stand by the window you are interested in, make sure the Sun Seeker app is running, then tap on the 3D View button to open the augmented reality camera view (shown above). You can use the app either in portrait or landscape mode. I am using landscape in this case because it allows me to show more points of interest for this article, but you can choose whichever helps you see more of the relevant parts of the sun’s path.

Due to the inherent limited field of view of the camera on the device, you may need to move it around to see the entire range of view through the window. However, in this particular example we will start by looking at the features of interest we see by looking towards the position of the sun at sunrise.

In this case I have in fact taken a screenshot at precisely the time of sunrise on this day (12th May). Choosing a time at which the sun actually visible from the window is helpful in that it allows us to be sure that the sun’s position and path is accurately aligned with the true direction of the sun. i.e. to have an accurately calibrated heading. Of course this will not always be possible, so there is a detailed explanation below describing various other ways of calibrating the heading, if needed, but for now we will continue on the assumption that we already have the best available heading calibration (as we obviously do in the sample screenshot shown above, given that the sun’s icon does align exactly with the actual sun).

What we can see in the above screenshot is that today the sun is rising at about 6:50am and will follow the yellow path line, disappearing behind the building at about 9:20am – this means that today we could get a maximum, on a cloudless day, of about 2.5 hours of direct sunlight.

By contrast, the blue path line shows the path at winter solstice, which is limited to a maximum of about 2.2 hrs of direct sunlight.

The green line shows the path at equinox (and therefore intersects the horizon roughly due east). Although this path extends well above the top of this particular screenshot, and you would point the camera upwards to see the full extent of that path, as I did here to obtain the following screenshot.

Here we can see that on the green equinox path line the sun remains out until just after 12pm, after having risen at around 7am, so provides a maximum of just over 5 hours of direct sunlight.

Following the red line (summer solstice) in a similar fashion shows rise at just before 6am and also disappearing at about 12am, so provides a maximum of about 6 hours sunlight.

What further conclusions could we draw?

This window gets morning sunlight year-round. Nice! However, in mid-winter it receives a maximum of only just over 2 hours (on sunny days), and then only at low solar elevation (disappearing behind the building when it has only risen to about 20 degrees elevation). This means that this room might be somewhat cool in winter – and especially so when the morning is cloudy. In spring, summer or autumn/fall though, it receives quite copious amounts of sunshine and you might need shades if you aren’t a full-on sun lover, or want to protect items in the room from UV exposure.

How to Calibrate the Heading

As you can see from the above analysis of this window’s sunlight, having an accurate heading on your device is important as if it is not accurate, it can significantly distort the projected timing of the sun’s emergence or disappearance into shade.

Sun Seeker calculates the position of the sun very accurately – to better than one second or arc – but the device’s compass may not be very precise, can be significantly affected by any surrounding magnetic interference, and may need “massaging” to bring to optimum accuracy.

Therefore I strongly recommend that, if you are doing anything more than getting a rough overview of solar exposure, rather than relying on the compass being accurate, you use one of the following methods instead.

  1. Set the heading manually from the actual sun’s position (only possible if sun is visible from your current position of course). To do this, first switch the 3D view into gyroscope only mode (by tapping on the compass icon symbol in the toolbar), and then manually drag the screen until the sun icon aligns with the actual visible sun. Once you have done this, the heading will likely on drift very slowly out of correct alignment – just recheck it and re-align it in the same way, from time to time, as needed to maintain the accuracy.
  2. Set the heading manually from the known position of a visible landmark, by using Sun Seeker’s Reference Azimuth feature. For a full explanation of how to use this feature see this earlier blog post: https://ajnaware.wordpress.com/2014/08/19/sun-seeker-how-to-use-the-new-azimuth-calibration-feature/

If you must rely on the compass because these other methods are not feasible in your current circumstances (i.e. sun not visible, and no known landmarks are visible), then I strongly recommend that you perform a compass calibration manoeuvre instead, to get the best possible compass performance and accuracy. This involves rotating your device a few times around 3 different axes, while an app that uses the compass (such as Sun Seeker) is open on your device. See the following video for a demonstration.

Sun Seeker Pro for macOS

[ Republishing – this article was first posted Nov 8, 2016 ]

Icon_v1Sun Seeker Pro is a macOS app that projects solar path, solar energy, sunlight exposure and other solar related information onto Photo Sphere images or other user-supplied images such as site plan or overhead architectural schemas, and performs various types of analyses on this data, including auto-generated shade data.

Some things you can do with this app:

  • Visualise the annual solar path over photo imagery
  • Visualise solar direction for all hours, all seasons on on overhead satellite view, or site plan
  • Auto-generate shade silhouette data directly from the Photo Sphere
  • Get reports of sunlight exposure periods (taking into account shaded areas)
  • Get detailed reports of solar energy availability, based on selectable panel characteristics (taking into account shaded areas)

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The app contains a couple of demo locations for you to play with. You can open these to view them by choosing Location / Open from the app’s menu or Location button. The demo projects already contain Photo Sphere images, which may be panned and zoomed in the 3D view.

However, when creating a new location project for your own chosen locations, typically you will first want to obtain a Photo Sphere image for that location. This might be a site at which you intend to shoot a movie scene, a location (roof) on which you want to install solar panels, the centre of a window in your house for which you want to find annual sunshine hours, a site for a tennis court for finding best playing hours, a location at which you intend to take a photo of a sunrise or sunset, the location of a tree or plant whose solar exposure you want to examine, etc.

Note that you can use the app without a Photo Sphere, simply by searching or browsing for any address or map location. However, the most powerful features of the app (especially when using shade data) rely on having a Photo Sphere for the location in question.

Photo Sphere images, which are also known as spherical photos, or 360deg photos, can be taken with Google’s free “Street View” app, available on both iOS and Android. You use this app to take a series of photos which cover the entire sphere, around, above and below where you stand. The app automatically merges the photos (also known as “stitching”) into one large rectangular area that is a linear representation of the entire spherical view. You can export any Photo Spheres you take and use them to open a new location project in the Sun Seeker Pro app.

Photo Spheres may also be taken in a single shot with a dedicated spherical camera, such as the LG 360, GoPro Omni, Samsung Gear 360 VR, Ricoh Theta S, and others – not my sponsors 🙂

When you create a new location project with a Photo Sphere image, the app reads the geotagging information that forms part of the Photo Sphere’s internally stored metadata. If this information is complete and correct, then the app will automatically already be set up with the exact location and compass heading (azimuth) on which the photo is centred.

In those cases where the location and heading information included with the Photo Sphere are either missing or potentially inaccurate, the Sun Seeker Pro app provides some editing and calibration tools.

The Sun Seeker Pro app also automatically finds regions of shade in the Photo Sphere image. In many cases this automatic shade detection is quite accurate. However, adjustments to shade areas may be made manually if required.

This shade information directly affects various reports that the app generates, both in terms of insolation times/periods and in terms of solar energy availability calculations for the site.

Once you have created a location project with a Photo Sphere, you can switch between any of the following views:

  • Compass – an overhead hemispherical view
  • Map – an overhead satellite image map view, with solar direction arrows overlaid
  • Image – viewer for an (optional) user supplied overhead image for this location, which could be a satellite image from a browser or another map application, overhead photo from drone, or a site or house plan or drawing (which must already be aligned with north upwards).
  • 3D – a viewer of the (optional) Photo Sphere, for this location, which can be zoomed and panned to see areas of interest, with solar path and position overlaid.
  • The user can set and date/time, scroll date or time, and also even play forward or backward through time for any of these views, to see the solar position and path update correspondingly.

Sun Seeker – How to use the new azimuth calibration feature

I’ve just submitted an update to Sun Seeker for iOS – v4.3.

This update contains an experimental feature which addresses one of the most difficult aspects of using the device’s compass to obtain an accurate heading, when using the augmented reality 3D view to see the solar path. This article seeks to explain what this feature is about, and how best to use it.

Note that the Android version of Sun Seeker does not yet have this feature. I will be relying on feedback from iOS users before deciding whether to implement it in the Android version.

In the last major release (v4.2), I introduced the ability to toggle between Compass+Gyroscope mode and Gyroscope-only mode. This was already a big leap forward, because the gyroscope-only mode allows users to manually adjust the 3D View heading simply by dragging it manually.

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The gyroscope-only mode allows you to set the heading manually, and the device then holds your setting relative to the gyroscope. Although there is likely to be a slow drifting of the gyroscope-only data, provided that you were able to set the heading accurately, this will work well for short periods of time – more than likely long enough to get all the information you need from the app.

Of course this all depends on you being able to set the heading accurately yourself. If the sun is out, then this is very easy – just line up the sun icon in the camera view with the actual position of the sun! Easy. 🙂

But what if the sun isn’t out? Well this is where the new “Azimuth Finder” feature comes in. Tap on the settings (gear) icon in the 3D View, and you will see two new options at the bottom of the list of settings.

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  • Show Reference Azimuth – If you have already selected a location, use this option to to toggle the display of an azimuth line corresponding to the selected location.
  • Set Reference Location – Tap this to open the “Azimuth Finder” view, and select a location or landmark within your line of sight, to use for your reference azimuth.

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All you have to do in this view is to use the map to browse to a landmark or location that is visible from where you are now. It must be somewhere that you can identify when looking later through the 3D camera overlay view. When you have found a suitable location, just tap and hold to drop a marker. The app will use geocoding to assign a name or address to the location, and calculate it’s azimuth from the current device location.

In this particular example, I am (just) able to see the top of the Sydney Harbour Bridge from here, despite the rain and low cloud, so that makes a good landmark to use.

Then, as soon as you tap “Done“, you are returned to the 3D View, and there is now a new line showing the azimuth of the selected location. Note that you will only see this line if you are already looking in approximately the right direction! Otherwise you may need to pan around until you bring it into view.

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You may be able to make out the Sydney Harbour Bridge in this screenshot – just to the right of the chimney, directly below the centre cursor.

As this 3D View is already in gyroscope-only mode, all I needed to do next was to manually drag the white azimuth line to the actual location of the bridge – in this case four degrees to the right. And, voila, we now have a very well-calibrated heading!

Note that if you leave this for a while it may drift off again little by little, due to gyroscope drift. In that case, simply repeat the same calibration procedure.

Once you’ve selected a particular landmark for calibration, it is remembered (and the heading automatically adjusts itself if you change location yourself), so you can just switch the reference azimuth line on or off via the settings icon. And at any time you can choose a different reference location too, as you will obviously need to do if you move to a new location from which the original landmark is not visible.

Sun Seeker Sizzles!

The Sun Seeker app has continued to be enhanced and honed in a series of updates, the most recent being v2.8, which includes a modernised interface – yep, those are indeed flat button faces. 😉

Sun Seeker v2.8 compass screen
Sun Seeker v2.8 Compass Screen

These updates seem to have attracted a bit of positive attention resulting in several new blog reviews, culminating in the following fabulous review from top-notch reviewer John Martellaro (@jmartellaro) of The Mac Observer. This is a must-read review, not just because it is positively glowing, but also because John saw fit to include my detailed answers to his probing questions, including some inside information on how the app works, and especially importantly on how to ensure optimum compass calibration of your device.

Just to show a little more of the app here, my own favorite feature update is the ability to select date and time on the map view via a scroller.

Sun Seeker Map View

 

Sun Seeker Test Shots

Here are a couple of images from Sun Seeker put together (unsolicited) by a generous and enthusiastic New York based photographer/cinematographer – Hal Hansen.

He’s currently revamping his website and I’ll provide a link to it here when it’s ready. Thanks Hal!

I love the way he’s featured an iconic yellow cab which is a New York signature. Did anyone notice that it’s not actually the same cab in each shot? That’s clever photography! 😉

Sun Seeker Update v1.5

As part of a series of planned updates for the Sun Seeker augmented reality iPhone app, the latest update v1.5 has just been approved by Apple.

For a video demo of Sun Seeker see this earlier blog post.

The main changes for v1.5 are:

  • Enhanced performance for smoother compass dial rotation
  • Added new table of annual rise and set times
  • Added new table of sun’s daily azimuth and elevation
  • Added tap action to rise/set label to see local times instead of intervals
  • Better handling of disabled Location Services
  • More efficient use of GPS – now only used briefly on startup
  • Fixed some minor bugs and issues with date changes

[Note – v1.5.1 update has been submitted to fix OS3.0 backward compatibility and missing sunset times for some locations west of GMT.]

Following is a more detailed description of some of these items.

1. Enhanced Compass Dial Rotation

The compass dial in Sun Seeker includes text which retains its orientation relative to the device regardless of the compass rotation, and this means that at least part of the image needs to be re-rendered for each incremental rotation of that dial as the compass rotates. Previously the whole image was being redrawn each time, and that performance hit meant that the dial motion was quite jerky when it needed to make large rotational changes. The new implementation involves much less redrawing, and hence allows the compass to be much more responsive.

2. New Tables

The table of rise and set times spans the entire year, and hence allows you to look up rise and set times for any given date.

The table of the solar path lists the sun’s azimuth and elevation at 15 minutes intervals throughout the currently selected day.

3. Tap action to see rise/set time instead of intervals

This was added simply for clarity. Tapping on the rise/set labels on the compass screen toggles the display between showing the rise and set time in local time versus showing time duration between now and the rise and set times.

4. Better handling of Location Services status

A problem to date has been if the user has switched off the device Location Services or (perhaps accidentally) disabled them for this particular app. In these cases the app can only use its last acquired location data, and in this case the app shows data which is correct for that old location, but incorrect for the user’s current location.

This issue has been the biggest generator of email support requests to date, but I now expect that this will lessen considerably, because I have implemented clear warning messages which pop-up whenever location services are disabled, each time that the app starts up or resumes from background.

5. More efficient use of GPS

Previous versions of the app left GPS on continuously while the app was active (although off when inactive or in background), and this presented the app with ongoing positional updates while it was open. But for the sake of efficient use of GPS, it seemed unnecessary to leave it on once the location had been determined to a reasonable accuracy, so GPS is now only on as long as location has not been found to reasonable accuracy. However an important point here is that the app should re-query its location not only every time it starts up, but also whenever it resumes from background. The reason for this of course is that the device may have changed location while it was in background – for example it may resume from background after the user has traveled somewhere by air!

6. Future Updates

By far the most common request from users has been to allow selection of other cities/locations rather than just the current current, and this is the next major feature planned. But please note that it is not a trivial update! A particular difficulty here is in ensuring that the local times reported for other locations respect the correct timezones and daylight savings rules for those locations throughout the year. However, I do have a solution planned, and hope to be able to do this within a reasonable timeframe.

The next most common request has been for an Android version. Due to the particularly technical nature of the app, and the fact that I personally have no grounding in Android development, this is a much more difficult proposition. However I have been looking to outsource it. I apologise to those who have been waiting impatiently, and I can assure you that these plans are progressing.

In the meantime, I hope you continue to enjoy the app!

Sun Seeker Lite

I’m pleased to announce the arrival of Sun Seeker Lite – a free version of Sun Seeker (finalist in the 2009 Best App Ever awards), albeit without the augmented reality view!

After my recent experiments and experiences with in-app purchase, I’m now putting more effort into the Lite version concept. Although it requires creating a whole new app, in practice it is simpler and safer than the in-app purchase method, for a range of reasons. In fact I have already added an Oz Weather Lite version of the full Oz Weather app, and Sun Seeker Lite is my second Lite app.

That is not to say that the decision of exactly what features to put into a Lite version is an easy one. In this case I removed all augmented reality features, which is of course the big selling point of the full app, but on the other hand I’m pleased enough with the look and feel of the main screen’s flat compass view, that I think it will create the right impression for users, and persuade them that the quality is good enough to warrant purchasing the full app.

Despite the fact that it does omit the augmented reality view, the flat compass view in the Lite app can still be very useful in many situations. Please give it a go, and pass on the word to others if you like it, or perhaps even (gasp!) leave a positive review. 😉