Back in 1995, a little packet of laminated cardboard diagrams fell through my letterbox. Dave Hewitt, editor of The Angry Corrie, wanted me to write a review of these items. Which I did—it appeared in TAC25, Nov ’95-Jan ’96.

They were called ViewFinder Panoramas, they’d been created by Jonathan de Ferranti, and in my opinion they were things of exquisite, minimalist beauty. Each laminated strip showed the view from the summit of some named hill, colour-coded and annotated to allow the easy identification of other hills. They had been produced from Ordnance Survey Digital Elevation Models, rendered so as to depict the curvature of the Earth and the effects of atmospheric refraction, and then carefully annotated with the names and distances of individual peaks. On occasion, magnified sections were inset to provide additional detail. And features near the horizon were subtly stretched vertically so as to bring out the detail without giving the impression of distortion.

Here’s a comparison of the view eastwards from the summit of Ben Hope, compared to the corresponding ViewFinder diagram:

View of Ben Loyal from Ben Hope
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Ben Loyal view from Ben Hope ViewFinder
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From the colour-coded distances, to the sector indicator at bottom left, to the bearings along the top of frame, it was a beautifully designed product. ViewFinders retailed for £1, or £1.50 for the larger, more complex products. You could order a bespoke view from the summit of your favourite hill for £16. Nowadays the entire catalogue is freely available on-line, covering worldwide views.

In 1999, Jonathan de Ferranti and I wrote an article together for the Scottish Mountaineering Club Journal, investigating whether it was possible to see any part of the Cuillin ridge in Skye from the Cairngorm plateau.* In this, we used Jonathan’s ViewFinder technology to revisit a question first raised by Guy Barlow in the same journal in 1956.Barlow had constructed a wood and paper model, and concluded that Sgurr a’Ghreadaidh, on the Cuillin ridge, would be visible from the summit of Cairn Toul in the Cairngorms, because of a fortuitous sightline down the length of Glen Shiel. Jonathan produced a rendering of the same view and discovered that, although Barlow had the alignments exactly correct, he had neglected to allow for the position of Bla Bheinn, which sits east of the main Cuillin ridge, and which neatly blocked the view of Sgurr a’Ghreadaidh. The glimpse of Bla Bheinn, 90 miles away, was minute, occupying more or less a single pixel of the ViewFinder panorama, and in reality would need a telescope, strong refraction and perfect seeing conditions to appreciate. (In the scan below, Bla Bheinn takes its Anglicized spelling, Blaven.)

ViewFinder view of Blaven from Cairn Toul

All of this is a roundabout introduction to Fabio Soldati’s excellent PeakFinder app, which is the natural successor to ViewFinder—indeed Jonathan de Ferranti is credited with providing some of the Digital Elevation Model data used by PeakFinder. With the huge leaps in processing speed and storage capacity that have occurred during the last two decades, it’s now possible to perform the necessary rendering tasks on the fly, producing annotated panoramas of pretty much anywhere in the world, on demand. Apps are available for Android and Apple phones at a cost of a few pounds, and there’s also a rather lovely on-line version. Here’s the view from Ben Hope again, compared with PeakFinder‘s on-line rendered view, and the version displayed by my rather primitive Android phone.

View of Ben Loyal from Ben Hope
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On-line PeakFinder view from Ben Hope
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Android PeakFinder view from Ben Hope
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The on-line version provides shading, shows lochs and coastlines, and offers a few other bells and whistles, but the more basic rendering on my phone is beautifully clear. And having this software as a phone app produces multiple benefits. It can use the phone’s GPS to generate an annotated panorama for your current location, wherever that might be. And the app keeps its database locally, so it will work without a phone signal, provided you have already made the appropriate download. One quick 20MB download covers the whole of the UK, and you can add or delete additional areas as required, with most of the world available in handy chunks of data. If you have a smarter phone than I have, the app will use the phone’s orientation data to overlay its labels on the real view seen by your phone’s camera. This not only lets you easily figure out what you’re look at, but allows you to keep and share an annotated photograph. (Details on that one here.)

Apart from using your phone’s current location, you can select a different location by choosing from PeakFinder‘s extensive names database, tapping on Google Maps (you need a data connection for that), or by entering latitude and longitude coordinates.

Tapping on any of the named peaks in the displayed panorama brings up some information about that feature, and you can also flit across to look at the view from its summit. The names of all the visible peaks in the panorama can be displayed, searched, and sorted by elevation, distance or heading. Tap on one of these names, and you’re returned to the display with a handy marker pointing out that summit’s location. So with a couple of quick taps I was able to establish that the most distant feature visible from the summit of Dundee Law is Windlestraw Law, east of Peebles and a remarkable 88km away. Here’s the PeakFinder display showing me where to look for it:

Windlestraw Law from Dundee Law, PeakFinder app
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The display units are configurable, and you can pop up depictions of the tracks of sun and moon across the sky, for a given date. Here’s the sun rising over the Orkneys from Ben Hope:

PeakFinder sunrise from Ben Hope
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Is it accurate? It certainly seems to be, when compared to summit photographs from my collection. For me, Jonathan de Ferranti’s ViewFinder panoramas are the gold standard, so I challenged PeakFinder to show me the extremely marginal view of Bla Bheinn from Cairn Toul that Jonathan identified twenty years ago. Here it is again:

ViewFinder view of Blaven from Cairn Toul

Here’s the view from the web-based version of PeakFinder, with Bla Bheinn again occupying pretty much a single pixel:

Web-based PeakFinder view of Blaven from Cairn Toul
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And here’s the view on my phone, zoomed in to its maximum extent:

Phone based PeakFinder view of Blaven from Cairn Toul
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No Bla Bheinn. I suspect the difference comes from either the screen resolution or the processing limitations of my dumb phone.

Setting aside ridiculously exacting tests like the one above, this is an extremely impressive bit of a kit, even more so if you have a phone that will allow you to use the app’s photographic annotation mode. If you’ve ever sat by a cairn and indulged in an endless, fruitless debate about the identity of some little notch on the horizon (and which of us has not?), then you’ll certainly want to spring a few quid on this lovely little app.

* “On Seeing The Cuillin From The Cairngorms—Again” SMCJ 1999, Vol. 37 No. 190 pp 42-8.
“On The Possibility Of Seeing The Cuillin From The Cairngorms” SMCJ 1956, Vol. 26 No. 147 pp 16-24.

2 thoughts on “PeakFinder”

  1. I love Peakfinder – we use it quite a bit for our planning our Scouting peak-peak mirror signaling activity, since the mirror flash won’t work if we don’t have line of sight! Also, when we get a flash and bearing, we can use Peakfinder to make sure the direction of the flash is from the peak where the other Scout team is. I made a short video tutorial for the Peakfinder website some years back, here:

    Two other good websites for determining what can be seen from a given location (though not nearly as responsive – both require entering inputs and generating the analysis) are: Ulrich Deuschle’s “Create a Panorama” website, which lets you zoom to 30x (6,000 pixels/degree) [It is also of the opinion that Bla Bheinn has line of sight to Cairn Toul] and

    While does not generate nice panoramas, it will do a bespoke line of sight check between your reference point and any potential target if you click on the potential target on the map, and also show you a profile along the potential line of sight, which you can click on to precisely locate potential obstructions. You can also display contour lines, find local high points, and vary the assumed index of refraction.

    I generated and saved the Cairn Toul analysis, which is here: and clicked arount on Bha Bheinn. does NOT think that Bha Bheinn is visible from Cairn Toul.

    Given that the underlying DEM models are cited as having 10m or so uncertainty, don’t account for vegetation, etc., I suspect that this intervisibility may be too close to call using the DEM models alone. Microwave tower planners typically do a final line of sight check using a signal mirror flash before committing – that would be a possibility here.

    There’s a faint chance that those two points were sun-flashed during the Ordnance survey of Great Britain using heliotropes ( ) – there were 11 links of 100 miles or more flashed during that survey:
    ““The sum of all the distances or sides in the principal triangulation is about 206,710,000 feet, or, in round numbers, exactly ten times the radius of the Earth (radius of the Earth 20,890,000). The mean length of a side is 35-4 miles. There are 37 lines whose lengths are between 88 and 90 miles; 18 between 90 and 100 miles in length; and 11 exceeding 100 miles in length. The longest side in the triangulation is 111 miles—viz., that from Slieve Donard to Sca Fell.”

    Of course, during the Ordnance Survey, they were willing to camp out on the survey sight for as much as weeks waiting for that rare moment of good sun and clear air …

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