Land-Form PROFILE^® Plus FAQs

1. What areas are available?

Great Britain is available and covered by different resolutions and accuracies. Over a third of the tiles contain data at sub-0.5m vertical accuracy. See the accuracy map for details.

2. The product includes high-accuracy data of flood plains. Are these areas at a high risk of flooding?

Not necessarily; the flood plain extents we capture the high accuracy data for are derived from the Environment Agency’s 100-year flood map. Any area that has flooded in the last 100 years is included.

3. Where has the LIDAR been sourced from?

In the summer of 2004 we undertook an open tender exercise, sourcing high-accuracy data from interested bidders. This resulted in a successful bid from the Environment Agency to include their LIDAR data.

4. Do you plan to roll-out more data at higher accuracies?

We will be looking at market requirements on what the priority areas are. It is possible that we will never have national cover at a resolution better than the base Land-Form PROFILE mapping if there is no customer need for it.

5. Are there plans to make Land-Form PROFILE Plus available online?

No, although this will happen when it eventually becomes a layer in OS MasterMap^®.

6. Is the product supplied with metadata?

Yes, metadata is included with each post, which includes information such as date of generation and method of capture.

7. Does the product come with any other tools, such as overlays?

No, it is supplied as a bare earth DTM.

8. How are roads represented?

Roads are flat transversely and smooth longitudinally.

9. Does the product contain feature heights?

No, these were removed from the product to create the DTM.

10. How is the product edgematched?

All improved data forms a continuous surface. Where improved data meets original Land-Form PROFILE no edgematching has been undertaken.

11. How does the product differ from Land-Form PROFILE?

Greatly improved accuracy and higher resolution is the most important difference.

Other differences include

• the introduction of ArcGrid format; and
• the move to height values representing pixel centre and not pixel corners (as in Land-Form PROFILE). This is a significant improvement as it means that there are no duplicate height points along tile edges.

Apart from the improved accuracy and higher resolution of Land-Form PROFILE Plus, one important difference is that the height points will fall in different places.

In ArcGrid ASCII format the centre of the pixel is used to calculate the height. This means that in 2-metre resolution areas the height is captured at odd-numbered points, for example 1 metre, 3 metres, 5 metres and so on from the edge of the tile.

In the exististing Land-Form PROFILE product the height points are captured at even-numbered intervals, so they match between different tiles at tile edges.