All The Views

Launch day

Mon, 09 Feb 2026 00:00:00 +0000

Ryan and I are very proud to announce the launch of this website sharing the findings from our months of hard work. You can read more about our technical journey on our personal blogs: Ryan and Tom.

We have lots more plans for the project, so watch this space! Subscribe to our RSS feed.

Commentary from around the web

About Us

Mon, 01 Jan 0001 00:00:00 +0000

Tom and Ryan are two friends united behind a single problem: finding the longest line of sight. Ryan met Tom through a tech forum, HackerNews, after reaching out to recruit him for a company opening. They instantly clicked and have kept in touch since.

Recently (in July of 2025), Tom started working on an algorithm to find the longest line of sight, and Ryan noticed it through a post on a tech forum explaining the project. For the last 6 months both have spent innumerous hours engineering a tool for the longest line of sight for every point on the planet, and to let others explore the beautiful world and all its long lines of sight.

FAQs

Mon, 01 Jan 0001 00:00:00 +0000

How Did You Do It?

Tom and Ryan go into detail on their respective blogs:

What Assumptions Did You Make?

The original source of our data is from NASA’s SRTM survey which is ~100m resolution analysis of the planet’s elevation data. It is known to have some issues so we used a cleaned version kindly provided by viewfinderpanoramas.org.
We used a globe earth meaning it is an approximation of earth’s shape, as it is an oblate spheroid.
We take refraction into account, and we use what the GIS community has calculated to be the world average, which is a refraction coefficient of 0.13.
The height of the observer is 1.65m or 5'5".
Each viewshed is calculated using 360 lines of sight each seperated by 1°. This could potentially miss some longest lines of sight, but it is considered to be the optimal resolution to balance the accumulation of errors and computational costs. For more details, see: Siham Tabik, Antonio R. Cervilla, Emilio Zapata, Luis F. Romero in their 2014 paper Efficient Data Structure and Highly Scalable Algorithm for Total-Viewshed Computation https://ieeexplore.ieee.org/document/6837455
All computation is done on AEQD reprojections of the raw data. For the longest lines of sight on the planet, ~500km, the worst case errors caused by this projection can reach ~0.0685%. This error is only relevant to viewsheds at the edge of the computable area of tiles, therefore those viewsheds around 500km from the centre of tiles.

Is The Source Code Available?

Yes. The core algorithm. The pipeline and web app.