Hacker News Reader

Comment by hanoz | Hacker News Reader

I'm very pleased you like it! (tis a side project of mine). Did you try the 3D button? That's quite fun.

That's really fun. Any chance of data for Ireland? As you probably know, "all good things lead to requests for more features".

I can see the lines left by ploughs in fields! Where did you get the data? (Or is there a write-up I've missed the link to?)

I'm not much of a one for write-ups I confess, but broadly:

The raw data comes from the Environment Agency and Natural Resources Wales as .asc files, which are just a big 2d array of height values in text file, in this case covering 1km2 each.

I downloaded all these and wrote a script to produce .png tiles using a "hill shading" algorithm, i.e. make pixel darker if pixel to top left is taller, using C#.

Once I was getting nice results I rented a hefty server at AWS to run it on the whole dataset for 24 hours, generating 2 million .png files, then used leafletjs to display them slippy map style.

I was originally hosting the tiles on AWS but the egress fees were too much so I move them all to a 3€/month bare metal arm server at Scaleway.

The 3D stuff re-fetches the raw .asc files from the source agencies on demand using a AWS Lambda script which cuts out the 1km2 of interest and passes it back to the web server, which renders it using three.js for the surface texture mode, or potree for the pointcloud version.

The website itself is built in asp.net core, running on a $10/month box at Digital Ocean.

That hill-shading algorithm explains why forests are so staticky.

In theory, you could combine terrain and surface models[0] to detect and colour features… but that's tricky.

[0]: https://lle.gov.wales/catalogue/item/LidarCompositeDataset/

A friend is asking: "When will it be finished?"

By which he means, "When will it be populated with more data?"

I presume he's asking as his particular place of interest won't let him view 3d or pointmap views.

Thanks! x

- ed - reading this back, this sounds rude - sorry, just caught up in the excitement.

The Environment Agency are currently running a programme aiming for full coverage (of England) completing this year. Once that is ready I'll have to regenerate all my map tiles and hopefully have all the remaining gaps filled in then.

Natural Resources Wales is aiming for similar by Winter 2022 apparently.

Oh! Well done!

Yes, I did try it, as too the three other people I've since shared it with.

I like the point map version too - I've a grab of a 'minecarft-looking version' of my home village - wonderful!

It's amazing. Could you add a layer to see the "normal" satellite view overlaid?

The source data is based on a different projection to that usually used in web maps so that's not easily achieved unfortunately.

This is very cool! Do you know how old is the data, generally?

Reply on news.ycombinator.com