Add OSTN15 to QGIS 2.16

As you may be aware, the United Kingdom has a new transformation model that is OSTN15…..But why? What does it mean to the geospatial community?

Without being too nerdy, tectonic plate movement means that the “model” surface (the geoid) is slowly moving from best fit for the coordinate system. It has been 13yrs since Ordnance Survey implemented OSTN02 so the shift since then is enormous…..a whole 1cm and vertically it is 2.5cm. See this article here from Ordnance Survey.

The whole story is that sensors and our ability to calculate our positi0n relative to both the mathematical models and our relative position to those is constantly evolving too. So, just as OSTN02 revolutionised the accuracy of projecting GPS (WGS84) coordinates using a grid transformation (250 points over the 7 parameters used until 2002), OSTN15 both uses the OS Net of 250 points but has also been improved further with 12 zero order stations with accuracy of 2mm horizontal and 6mm vertical.

So how will this change the way you use your GIS?

If you are already using OSTN02 for your transformations between EPSG 27700 and EPSG 4326 – then you will only see a 5cm improvement over a 1m area at best and this is based on the worst places in the UK, on average you will only see a 2cm improvement anywhere in the UK. To put this into context, when you are zoomed in to an A3 map to about 1:100, you are talking about a few pixels on the screen….it won’t be groundbreaking [at the moment].

Currently, as this goes to press, the OSTN15 transformation has only been available for a few weeks and it is still being tested on different software to ensure it works, I am told that ESRI UK have been testing it with their software as this is being written.

As with OSTN02, I’ve created a fix for QGIS and OSTN15, I will describe how to implement this further in this.

It’s all about the Proj

Proj (Proj.4) is a cartographic library which is based on the work of Gerald Evenden of USGS back circa 1980. Over time it has evolved to consume grid transformations and is used by GRASS GIS, MapServer, PostGIS, Thuban, OGDI, Mapnik, TopoCad,GDAL/OGR as well as QGIS.

There are many ways to use proj, without a GIS you can use it through a command line by defining parameters. QGIS uses the proj library by accessing a spatialite database called srs.db. This is held at .appsqgisresourcessrs.db in Windows and Linux.

The proj spatialite database is a relational database which, when analysed, holds tables for coordinate systems, epsg codes & transformations. What is really clever is that it recognises direction of transformation.

Why is direction important?

Most coordinate transformations go from the projected coordinate system to the geographic coordinate system, for example epsg 4277 to epsg 4326, OSTN15 bucks the trend and is the reverse direction, from 4326 to 4277.

As I found when I first tested OSTN15 with QGIS, I was getting a uniform 200m shift in the data which was being translated and I was really confused. After talking with the gridfile creator, I discovered that the file was created from ETRS89 to OSGB36, therefore the 200m shift I was getting.

QGIS is awesome, you’ve probably overlooked just how clever it is and so did I. Next time you run a transformation, or when you try this one, you may notice that there are 2 fields noted in the columns SRC (source) and DST (destination)…and this is a godsend for solving this issue, as QGIS can read the coordinate in both directions.


Show us the magic

So, I talked with Ordnance Survey and found that OSTN15 has been given the epsg of 7709 and created a new record with the srs.db which is distributed with Windows, Linux & Mac releases. To utilise this, all you need to do is to download the OSTN15 file from Ordnance Survey (here) and then place the OSTN15_NTv2.gsb file in the shared projections folder .shareprojOSTN15_NTv2.gsb this has been found to be correct in Mac and Windows (there should be similar in Linux). You know it is the right folder as there should be other .gsb files in there!


You can download the updated srs.db from here, this should be placed in the resources folder which can be found at  .appsqgisresourcessrs.db – I highly recommend changing the name of the srs.db file in this folder to something like srs.db.old before adding the new version, just in case it doesn’t work for your particular set up BUT it has been checked on Mac and Windows distributions of QGIS from version 2.12 through to QGIS 2.17.




Many thanks to Ordnance Survey for their help

Further reading about the model for Great Britain and OSTN15, I recommend this paper: A guide to Coordinate systems in Great Britain

Geobusiness 2016…THE place to be

From xyHt magazine 30/5/2016 – Original Posted here

GeoBusiness 2016 – London

Wow! Just wow [ed. Translation to US-English “Wow!!”]. Last week I was at the UK ESRI annual conference with 3000+ people crammed into the tight QEII conference centre, this still didn’t prepare me for GeoBusiness this year. The same venue as last year but somehow they’ve crammed in a few more stands and it was BUSY!!

Here are some stats:

  • 200 exhibitors from 17 Countries
  • 24 conference presentations
  • 85 workshop sessions

….and this was over just 2 days!

From the moment I got there at 9am until I got thrown out at about 4:30pm, I didn’t stop, as soon as one conversation finished, another began…such a great mix of Chartered Survey, Chartered Geography, Geomatics, GIS, Engineering covering all areas of geospatial work, it was hard not to be impressed.

GeoBusiness 2016 was held May 24th-25th at the Business Designn Center - Islington, London

GeoBusiness 2016 was held May 24th-25th at the Business Design Center – Islington, London

Ordnance Survey

One of the first companies I met was my old friends, Ordnance Survey. The headline “The most accurate and up-to-date geographic data now available for the first time in new application suitable for BIM projects” blazened across the page in front of me.

For a while I’ve been in contact with Ordnance Survey and been told many times that there was no interest in 3D (even though I’d worked on some in my employ there)….so it was a bit of a shock to hear that OS had been working with Cadline behind the scenes to produce a great new tool for Infraworks, called OS Model Builder.

Using the OS Model Builder you can rapidly create 2D and 3D building or infrastructure models which are BIM ready.

Gary McDonald, OS Strategic Relationship Manager said: “OS listened to feedback from the building industry and the result is Model Builder, a leap forward in bringing our world-class data under one roof and removing previous license hassles. We are also aware that when you are dealing with multi-million pound projects and making important decisions, you don’t want the risk of relying on inferior and inaccurate geographic data. You want the best and most current picture to work from.”

Ordnance Survey of the UK booth

Ordnance Survey of the UK booth

Avenza Systems Inc.

Next up I meet with Avenza, a leading developer of cartographic software, such as MAPublisher and Geographic Imager tools for [Adobe] Photoshop. as we chat about how cartography is changing, I hear that their mobile app has had over 1 MILLION downloads…..let’s just think about that, there are either a lot of kids thinking that this is a cool game or there are people out there actually using maps, Avenza maps to be more precise.

Avenza says that unlike other map apps that provide one view of a location using GPS coordinates, Avenzas PDF maps app provides a meaningful interface to measure distances, drop placemarks and share personal recorded data in various formats for use on land, sea or air. PDF maps is an award winning all encompassing solution for the use, distribution and sale of digital versions of paper maps to mobile devices.

My personal opinion is that it is a great app to use when travelling abroad as the maps can be accesses and used offline, removing the worry on international trips of that “International roaming” charge!

In other news, I noted that Mapublisher 9.7 was also announced with WMS now available to be managed, geopackage format now supported and the help system has been moved online…..

Avenza have been extremely busy these last 12 months!


I’m walking away from the talk with Avenza and I can’t help but be drawn towards a HUGE interactive table, this thing has to be 60 inches if not bigger and the images on it are crisp… is even harder not to believe that the city which I am moving around is an 3D model….it is so cool, it has shadows, real time sun position, atmospheric density….and that is before I point out that this is accurate to 15cm over the 130 square kilometres of London, it is expanding at a rate of 5-8 square kilometres a MONTH!

VUCITY Demonstration

VUCITY Demonstration

Sandor Petroczi, Product Manager of Vertex Modelling said: “Using a combination of photogrammetry, high res  aerial imagery and a highly skilled workforce, we are able to create our 3D model of London that can be used by any entity involved in design and planning of the city. We do not use any automated processes and although this is more expensive and time consuming, it allows us to create highly usable models with a consistent level of accuracy across the dataset. The team is currently capturing Camden and Southwark while updating existing areas from the latest 2015 imagery. VUCITY is an ideal solution for visualising the entire dataset.”

I’ve got to admit that I am very impressed but part of me is a little unsure about their claim to be the “first ever interactive 3D model of London” purely because I’ve seen a few 3D interactive models of London, one from CartoConsult, a company based in Swindon and also Garsdale Design (yes the one I work for!) although our model wasn’t served as a webGL to be interactive, it still won and ESRI award and I would suggest that it is a little better than 15cm, more like 4-8cm.


3D Laser Mapping

Walking away from VUCITY feeling very confused, I feel my phone buzz and I check my Twitter….and it’s Charlie Whyman from 3D Laser Mapping, asking if I’d been to their stand and I’d been REALLY impressed if I had.

Not one to shy away from a challenge I rock up, ready to rubbish such claims…but firstly Charlie is a girl and secondly their kit is pretty cool. Now, I don’t want that previous statement to come across as sexist, what I mean by it is that you come across a lot of men when you talk survey kit…A LOT of men, so having spoken on the internet with Charlie a bit, I had already put an image in my head….but no, not hairy, not wearing a hard hat, not even a pair of wellies….

Charlie of 3D laser Mapping and the backpack mobile mapping system

Charlie of 3D laser Mapping and the backpack mobile mapping system

ANYHOW, on display was a backpack type laser scanning system named ROBIN. about 8-10kg in weight and mobile enough to wear for a couple of hours at a time. I’m told that the portable battery pack would last you 3hrs (but is expandable). So that I can get an idea of HOW portable it is, I ask my human guinea pig, Tim Hughes, to put it on and see how it feels. Apart from looking like an extra from the Ghostbuster movies, it is extremely comfy and also it has a field of view of 330° and an 18MP camera. Best of all?….It is designed for outdoor and INDOOR capture, yes INDOOR (why I’m saying that in capitals, I don’t know).

At this moment, the ROBIN is waiting for the SLAM upgrade, which should be happening a little later in the year.

Mark Hudson of Geoterra said “Geoterra is very excited about the launch of the new ROBIN multiplatform mapping system. It’s become evident that there’s a gap in the sector for this kind of product and we’re sure it’ll prove to be an extremely popular addition to the marketplace”

The ROBIN mobile mapping system

The ROBIN mobile mapping system

So, to understand how the accuracy of the SLAM unit works (for indoor mapping) I went over to GeoSLAM to see if they’d talk….about all I got was a surveyor telling me how clever this device is and that it records you start point to high accuracy (typically 3cm but 1cm has been reported), once your position (indoors) is known, it then uses your route (provided you complete a circuit) to fully map the internals…..I asked questions about how it knows scale, units of measure, speed etc but was quickly faced with a blank face and the term “Really clever algorithms” – me thinks it is the beginning of a GREAT article for a future issue!


As I said above, having been wowed by the ROBIN system, I went over to GeoSLAM to find out more about how the SLAM works but what I didn’t say was they had a huge screen up behind themselves showing the rather clean and crisp scan they had made of the exhibition center. Any doubts I had were quickly extinguished the indoor detail looked really good, with a 100hz sensor  and capture of 43,200 points per second, I’m not surprised.

The model I was being showed was the ZEB-REVO, a handheld laser scanner which automatically revolves compared to ZEB1 which was, errr….”interesting” to use. An unrelated demo video of the ZEB-REVO in action can be watched here.

GeoSLAM's booth - their ZEB-REVO handheld scanner-mapping system was out and about on the exhibition floor on demo duty...

GeoSLAM’s booth – their ZEB-REVO handheld scanner-mapping system was out and about on the exhibition floor on demo duty…

Graham Hunter, Managing Director of GeoSLAM said “The ZEB-REVO fulfills a new niche in the market for ultra mobile indoor mapping solutions. Our early adopters have been thoroughly impressed with the ease of operation, vastly reduced  scan time and accuracy of the resultant point cloud, all from surveying just 1 closed loop. It won’t be long until the ZEB-REVO is the ‘go-to’ standard in the surveyor’s toolkit”

Severn Partnership

Just around th corner from GEOSlam, I bumped into a Ben McEwen from Seeable, also Severn Partnership. I couldn’t help be be drawn into talking about the VR Occulus Rift on the table….Severn Partnership are a survey company, they have some great pieces of kit, their main man, Rollo was showing me over their road kit (mounted on a truck) and it is impressive, they are all chartered surveyors and know their stuff, all except for Ben….there was all this amazing 3D vector buildings (also in VR) and Ben was telling me how easy it was. Here is the real story, Ben is from a GAMING background, he is used to modelling games and adding real physics using the unreal engine…no wonder the models looked so good but it goes to show that sometimes we are too hung up on the detail and the accuracy….when we are looking at a visualisation, how important is it that it is 1cm-5cm accurate when you can emulate real world physics?….Watch this space….

Severn Partnership's "Seeable" visualisation tools were demonstrated on a VR Occulus Rift headeset

Severn Partnership’s “Seeable” visualisation tools were demonstrated on a VR Occulus Rift headeset

Several mobile mapping systems were parked in an outdoor area. Severn Partnership's Rollo Rigby (left-center) brought along their mapping rig featuring a Leica Pegasus:Two

Several mobile mapping systems were parked in an outdoor area. Severn Partnership’s Rollo Rigby (left-center) brought along their mapping rig featuring a Leica Pegasus:Two

British Geological Survey

A couple of booths up from Severn Partnerships was the BGS, what I wasn’t expecting to see was a 3D mouse sat on the desk….why? BGS are now providing 3D geology data for almost all of the UK. How cool is that? Okay, so it is high level, you can obtain 1:10000 scale 3D data for a cost but for many cases, this is great news.


I bumped into these guys while gawping at a video of some mesh (point cloud) data being converted in one simple step into a vector polygon, no tricks, no messing with triangles, just a point and click conversion. Although currently (here in the UK) we are only able to access to version 1.2, look out for version 2.0 which takes things to a whole new level!

Point Fuse demonstrated their applications for converting point clouds to vector data

Point Fuse demonstrated their applications for converting point clouds to vector data


There were so many other great companies there, Leica, Trimble, TopCon and others but I see that I am already running close to 2000 words. In my opinion, the big conversation was 3D, everyone was selling it (albeit in different formats) and also good old fashioned surveying but using the new tools to make it more accurate and useable than ever before.

What a great event, let’d do it again next year!!

Nick D


More Photos…

Korec Group brought their mobile mapping buggy sporting a Trimble MX2 system. Parked behind that is a van with a Trimble MX8

Korec Group brought their mobile mapping buggy sporting a Trimble MX2 system. Parked behind that is a van with a Trimble MX8

Topcon's Sirius fixed-wing UAS

Topcon’s Sirius fixed-wing UAS

Topson's Falcon 8 multi-rotor UAS

Topson’s Falcon 8 multi-rotor UAS

– See more at:

Return of Ordnance Survey’s free OS OpenData Masterclasses

Data makes the GIS world happen, good quality data is essential and FREE good quality data is rare. So when Ordnance Survey released their Open Data product it was met with a mixed review. Initially there was some disappointment that there wasn’t the full level of detail that one would expect from the Mastermap product, but then we all knew, in the back of our minds that it was never going to happen.

Over time I have grown to love the OS Open Data, it links seamlessly into so many other data and there is never a question of the data quality. Last year I got the opportunity to go to the OS Open Data Masterclass at the Ordnance Survey here in Southampton, UK. Interestingly, the class was ran using QGIS 1.8 and had hands on demonstrations, showing how the data can be used to solve spatial problems.

So, how excited was I to see this morning, that Ordnance Survey are going to run another set of classes!! Have a look below at the blog from the Ordnance Survey and book yourself a place!!

From the Ordnance Survey blog: By , 8, October, 2013 8:00 am

People across Great Britain are being given the opportunity to gain a greater understanding of open data and the tools and techniques to use open datasets, through a series of free masterclasses, hosted by Ordnance Survey and supported by Horizon Digital Economy Research.

OSOpenData masterclass icon

materclass being delivered

This series of masterclasses will follow the format of previous workshops in combining theory and practical sessions, though we have updated the workshop material, still following the same journey of downloading the data, importing it into open source software and mashing with other open datasets to provide analysis. This class is ideal for those new to working with location data or anyone wishing to brush up on their skills.

We shall also be working with OS OpenSpace, Ordnance Survey’s free web mapping service that allows users to display up-to-date Ordnance Survey mapping in a web page or online environment. The workshop for this session will explain how to create file formats that can be easily imported into web mapping to show a list of locations.

For more advanced users, we will introduce our cartographic design principles and run through how to style map data features using open source software, and add the finishing touches to their map such as legends and scales bars.

Peter ter Haar, Director of Products and Innovation at Ordnance Survey, said: “The masterclasses are a great opportunity for people to experiment and start to develop with Ordnance Survey’s open data products and services. The sessions will provide the attendees with the tools and techniques needed to use, analyse and style a range of open datasets relevant to them.

“Today we are seeing thousands of ventures, products and applications underpinned by location data, and we want to make ensure that when developers are using digital mapping they think of Ordnance Survey. Through OS OpenData and OS OpenSpace anyone can access, for free, detailed and trusted digital mapping to support their products, services or applications.”

Ordnance Survey is able to offer up to 40 places at each master class, running from 9.30 am until 5.00pm each day. Locations and dates of the sessions:

Use our OS OpenData Masterclass finder to see where the nearest one is to you, and book your place today, or click on the relevant link above to reserve your space and obtain a ticket.

open data masterclass finder

We look forward to seeing you there!

Ordnance Survey Open Data Certified!!

Source: Ordnance Survey Blog 13th Aug 2013

There are so many different types of open data being released that it is becoming increasingly difficult for users to know the best to use in their applications, systems and technology.  To address this, the Open Data Institute (ODI) has launched the ODI certificate, which publishers can check their open data against.

The certificate runs through a series of questions that have been designed to help publishers:

  • explain what their open data is about
  • improve quality with other people’s help
  • respect people’s privacy and rights
  • build communities of interested people
  • deliver open data that people can depend upon

There are 4 kinds of certificate levels available; Raw, Pilot, Standard and Expert. Progressing through each level demonstrates an increased support network and robust information infrastructure.

“The Expert level sets a very high bar. This ambition underpins the potential we see in open data if it is published well. We don’t know who will be the first to attain an Expert certificate, but whoever it is will be celebrated!” (Jeni Tennison, Technical Director, ODI)

We put our Linked Data products, Code-Point Open, Boundary-Line and 1:50 000 Scale Gazetteer through the certification process and all are now certified “Standard Level”.

The application is really easy to use and the recommendations provided on how to improve the data to increase its rating have given us a clear steer on improving the openness of the data.

We now plan to put all of our other OS OpenData products through the same process to help to prioritise future developments and will published the results on our website.

Just where are the standards nowadays? (rant)

I am sure I am not the only one, you have the mother of all projects to get some spatial analysis done on by close of business and you go to merge the data for a spot of spatial join action and……there is no consistency, in fact every single data has a different way of structuring its attribute data.

Okay, so maybe you won’t be merging your data together for a spatial join, only a complete noob would be doing that (hello :P) but the point is, where are the standards? You buy survey data and most of its own data uses different attribute labelling formats, you download some Government Open Data and you spend 90% of your time trying to work out what the columns are about…if they are labelled at all!.

This is the modern age, we are looking at big data and cloud based systems yet we can’t even produce 2 data which talk to each other, it is well, embarrassing!! The ironic (or frightening) thing is that I have sat in a few meetings and discussions on Spatial Data Infrastructure (SDI) and each meeting has its own ideas about what needs to be addressed – The hydrographers want something specific to them and then the survey guys want something specific to them….and so on…

Well there are many SDIs about but here’s the problem….too many chiefs and not enough Indians (excuse the analogy), there are too many rules and regulations from too many sources for anyone to make sense of it & without any single specific governing body we end up with everyone having their own ideas over what they think should be right….only most of these guys are analysts, theorists and conspirators, not the people that work with the geospatial data on a day to day basis.

Just a quick scout on Wikipedia reveals just how many different standards are flying around at the moment:

My question to you all is why can’t the field with the object names in be called “Names” or the field with the WGS84 Latitude coordinates (in Decimal Degrees be called “Lat_DD”? Is this too complex?

I’m looking at my Twitter right now and I see 2500 of the best people to answer my question, if not, to spread the word and help to find the BEST answer to the question –

HOW DO WE GO ABOUT GETTING A DEFINITIVE SDI FOR FEATURE ATTRIBUTION?Please feel free to prod me and poke a stick at me if I am completely wrong and there is a standard which should be adhered to, in 10yrs of geospatial work I haven’t found it but I may have been looking in the wrong places. The closest I have got so far is the amazing work being done as part of the Inspire directive, though trying to comprehend it is a real pain and a few of the attribute names are not compliant with shapefile format eg “meanhigherhighwatersprings” & “Gradeseperatedcrossing” is never going to work!

All I want to do is to inter-relate my geospatial data and not spend hours having to rename and re-order the fields so that it I can join 2 tables together! It can’t be that hard….can it?

Nick D

Ordnance Survey Blog – Styling maps made easy

Styling maps made easy

By , 16, July, 2013 8:00 am

At Ordnance Survey we are committed to ensuring that our products are as easy to use as possible.

There is a growing need for our customers and partners to visually present our vector products in a suitable style, increasingly when it comes to serving mapping over the internet. For example, many companies serve Ordnance Survey maps via their Intranet service. Setting up these types of web-based services can be quite a time consuming process. Once all the geographic data has been loaded into a suitable database it can often take a while to apply the cartography – the visual portrayal of the data.

Understanding this, in December last year we released a set of Styled Layer Descriptors (SLDs) as one approach to help reduce the time and resource needed to properly apply cartographic styling. SLDs are commonly used in conjunction with a web server to style data for a web map service (WMS). Our SLDs have been developed in an open structured format and can also be converted to desktop GIS readable style sheets, enabling vector products to reflect the familiar Ordnance Survey look and feel.

Making sense of the data – styling Meridian 2 using our SLDs (raw data on the left vs. styled data on the right)

The SLDs can be downloaded free of charge under an open license which allows the modification of map features e.g. changing the colour of roads. They are available for all the products that we serve through our own WMS, OS OnDemand, including OS MasterMap Topography Layer and OS VectorMap Local.

Forth Valley GIS have recently migrated the SLDs into their own WMS. According to David Frankland, Systems Consultant, “having the SLD’s has saved approximately five days work for at least one (or two) of our developers/GIS support staff, so in terms of time and resource they have been very useful.”

Since December we have updated some of the SLDs to reflect product updates, style improvements and also in response to customer feedback. We have also been pleased to see members of the open source geospatial community sharing their own styles and experiences.

Lutra Consulting, a UK-based solution provider in the water engineering sector recently used our styles for OS Strategi to create Quantum GIS (QGIS) layer styles (.qml files) making it extremely easy for QGIS users to visualise this popular, small scale vector product.

Some customers will want to create a unique, custom style for their mapping, often to fit in with their branding. Our SLDs act as a great starting point for this and greatly reduce the amount of effort required. All the symbology is included in the SLD download pack so all a customer needs to do is tweak the colour values, feature weights and fonts in order to create a different look and feel. It is also easy to select the maps content and remove any features that are not required.


Our SLDs make it easy to create custom styles for our vector mapping products. This image shows 5 different styles applied to OS VectorMap Local

We will seek to continually improve on the cartographic styles that we offer in terms of both the visual output and usability. We also look forward to seeing more innovative uses of our data. You can see some great examples that have been developed using OS OpenData.

Ordnance Survey release New Height Product – OS Terrain 5 & Update to OS Terrain 50

Sourced from the Ordnance Survey Blog –  , 8, July, 2013 9:55 am
 OS Terrain 5 is our new fully maintained analytical height product modelling the shape of Great Britain’s landscape. OS Terrain 5 is a digital terrain model designed to work together with our large-scale products to provide the third dimension to analytical applications, such as flood risk assessment, development and wind farm location. You can see OS Terrain 5 below.

We’ve ensured additional modelling for features that are often used for analytical applications – such as such as major communication routes, lakes, quarries and urban areas. See the example below with the motorway network and Killington Reservoir.

OS Terrain 5 will be updated quarterly to ensure that latest data is available for customers. Featuring over 2.3 million contour lines and more than 280,000 spot heights, OS Terrain 5 provides highly-accurate, intelligent data.

Our first commercial product to be made exclusively available for download, OS Terrain offers 5 metre grid and 5 metre contour options within the one product.  We’ve also embraced open source standards and made the product available in a variety of formats, such as ASCII grid, Esri shapefile and GML 3.2 with detailed xml metadata for each tile of data.

The level of consistency and currency and ability to integrate with our large scale products makes OS Terrain 5 a welcome addition for terrain analysis and 3D visualisation by a wide range of customers.

Below: OS Terrain 5 overlaid with OS VectorMap Local, OS MasterMap Networks Water Layer and OS MasterMap Networks Rail Layer

Update to OS Terrain 50 now available

OS Terrain is the new family name for our height products and we launched OS Terrain 50 in April this year as part of our OS OpenData product portfolio. The national scale 50 m grid format has already proved popular for download and we’ve now updated the grid and released the 10 m contours for the product. You can view and download OS Terrain 50 in grid and contour format via our website now.

OS Terrain 50