Desktop - We are pleased to now offer desk-top (no survey) plans based on licensed Ordnance Survey (OS) Index map extracts with ground levels sourced from National Open Data LIDAR archives.

Logical Progression - This is the next logical progression from our value-management GNSS Levels survey provision. All data is initially sourced from national archives without the overhead of us physically surveying the site.

LIDAR resolution - LIDAR (Light Detection And Ranging) data is available in different resolutions across the country. This has been acquired by the Environment Agency using aerial reconnaissance. Some areas are restricted to 2metre, 5m or 10m resolution, though in many areas there is coverage of 1m resolution. This provides a grid of levels representing the prevailing ground height over each grid square.

Accuracy - There are two types of dataset, DSM - Digital Surface Model and DTM - Digital Terrain Model. The latter is generally derived from the former by removing buildings and other above-ground features from the DSM model. These spot heights are to Newlyn datum and are reportedly accurate in height to between +/-5cm and +/-15cm.

Terrain Models - We can use this raw data to generate terrain models (DTM, DSM or both in separate layers), contour models and grids of spot levels (say at 5, 10 or 20m intervals).

Preliminary Assessment - These desktop plans are potentially suitable for use in design/costing of Architecture, landscaping(cut/fill analysis) or drainage proposals, or for line-of-sight analysis, Planning impact assessment or Flood Risk assessment.

Mash-up(Map integration) - The plan could form the framework for your design/study model with other existing and design detail directly overlaid as required. We have experience and capability integrating different map data. We routinely overlay and combine other data such as Defra habitat maps, Local Plan spatial models, Title Plans and 3rd party design plans such as proposed highway improvements. These can be incorporated to enhance the CAD model as and when required as your project progresses.

Survey Integration - Our detailed topographical surveys are oriented to OS grid and Newlyn datum (ODN). So, we can accurately survey key specific areas and directly overlay them to the plan, for instance the immediate area around a proposed localised development. We can survey specific categories of detail perhaps missing from the desktop study, for instance to plot individual tree positions ready to support an Arborology Survey. Equally we could install and record a network of GNSS or TPS survey ground controls to orientate future surveys and setting out.

Value - This approach offers value for money, a relatively low upfront cost and potentially reduced lead times for design or preliminary assessment activities. There are OS Map licensing costs and our fees for processing and presentation, but this may be a fraction of the cost of a full land survey undertaking whilst giving you the flexibility to extend to a full survey, if and when required.