Elan Valley Drone Survey 2022
Air Survey of 10 upland peatland sites in Mid Wales flown in January and March 2022. The 10 sites were flown between the 12th January and 25th March 2022.
All sites were surveyed using an RGB vertical camera, then the data processed to produce digital surface models (DSM) and orthomosaics. The DSMs were processed to generate catchment, flow and contour vector data sets to assist with the peatbog restoration planning.
Drone details - eBee RTK unmanned aircraft system (UAS) by Sensefly. The eBee is an electric fixed wing Unmanned Aerial Vehicle (UAV), weight 1.1 kg, with a maximum speed of 110 km/h and a maximum wind capability of 12 m/s.
Camera - Sensefly S.O.D.A. RGB camera: 1″ Sensor, RGB lens F/2.8-11, 10.6 mm, resolution 5,472 x 3,648 px (3:2), Exposure compensation ±2.0, Global Shutter 1/30 – 1/2000s, Auto White balance, ISO range 125-6400.
Flight path - GIS ESRI Shape or kml files provided by the client were loaded into the UAS to provide survey area coverage parameters.
Data resolution - The UAV is programmed to fly the areas at a height that obtains an image resolution of between 3-4 cm/pixel, with an image overlap of 75%. The exact resolution is dependent on the ruggedness of the terrain; the resolution is set by the lowest resolution area of the orthomosaic.
Data capture - Once the orthomosaic sand DSMs had been created, the DSMs were processed to generate catchments, flow lines and 0.5m interval contour layers. This was carried out using QGIS and GRASS. The orthomosaics were then used to manually digitise peat and hag patchwork areas, hags, bare peat/water.
The 10 sites fell into the following categories:
• No visible peat bog areas or stabilised hags and gulleys.
• Signs of historic peatbog degradation, but currently stable/vegetated – vegetated hags and gulleys
• Visibly eroding peatbog areas – exposed bare peat, visible eroding hags and gulleys
- Identification
- Extent
- Distribution
- Quality
- Keywords
- Spatial Reference System
- Content
- Constraints
- Maintenance
- Metadata
Identification
- Identifier
- NRW_DS125407
- Alternative Title
-
- Aerial Survey: Elan Valley 2022
- Metadata Language
- English
- Lineage
-
Image processing procedures - The GNSS positions of the images were recorded during the flight. Post-Processed Kinematic (PPK) processing of the image positions was employed to bring the image accuracy to within 10 cm. This was carried out using the UAV control software (eMotion3), with the RINEX correction data from Leica Geosystems base station MACY at: Bro Ddyfi Leisure Centre, Plas Dr, Machynlleth SY20 8ER. The RINEX correction data was provided by HxGN SmartNet. Transformation Conversion from WGS 84, ETRS89 Geodetic to OSGB36/British National Grid was performed using: Ordnance Survey, Grid InQuestII software. The orthomosaic and Digital Surface Model (DSM) were created with Pix4D photogrammetry software, using the provided default settings.
Accuracy - The accuracy of the resulting orthomosaic and digital surface models is dependent on a range of factors, including:
• The height of the camera above the terrain – this varies depending on the ruggedness of the terrain.
• The contrast and detail in the terrain – featureless and uniform vegetation provides fewer opportunities to match points between photographs resulting in lower accuracy • Light levels – imagery flown on a bright day will have sharper images, resulting in more accurate pattern matching and thus registration
• The GPS satellite configuration at the time of the survey
• The proximity of the survey area to the GPS base stations used for applying positional corrections As a result, the accuracy will vary between the sites and within each site. The surveys were generally flown in moderate to good light conditions with the GPS positions post-processed using Leica SmartNet corrections and map projection transformations carried out using Ordnance Survey OSTN15 corrections, so the absolute positional accuracy should be better than 10cm in plan and 15cm in height.
- Additional Information
-
The full data report also provides additional site details on the flight path and resolution achieved for each survey. This report should accompany the data. Elan_DroneSurvey_2022_DataReport.pdf
Aerial survey: Elan Valley Air survey of 10 upland peatland sites March 2022 Exegenesis Spatial Data Management
- Dataset Reference Date (Publication)
- 2022-12-05
Temporal Extent
- Begin date
- 2022-01-12
- End date
- 2022-03-25
- Topic category
-
- Geoscientific information
- Inland waters
- Imagery base maps earth cover
Extent
Extent
- Geographic Extent
- Wales (WLS)
))
Vertical Extent
- Medin Extent Keyword
Distribution
- Format Type and Description
-
-
Geographic Information System
(
Unknown
)
- Specification
-
ESRI Feature Classes: [SiteRef]_boundary.shp [SiteRef]_DSM.tif [SiteRef]_Mosaic.tif [SiteRef]_dsm_Contours50cm.shp SiteRef]_dsm_WatershedBasins.shp [SiteRef]_dsm_WatershedStreamSegments.shp [SiteRef]_hagedge.shp [SiteRef]_patchwork.shp [SiteRef]_peat.shp Mp4 [SiteRef]_Flyby.mp4 SiteRef for 10 sites included: Elan1 Elan2 Elan3 Elan4 Elan5 Elan6 Elan7 Glanhirin Henfron Troedrhiwdrain
-
Geographic Information System
(
Unknown
)
Quality
Data quality
- Quality Scope
- Dataset
- Conformity
- Commission Regulation (EU) No 1089/2010 of 23 November 2010 implementing Directive 2007/2/EC of the European Parliament and of the Council as regards interoperability of spatial data sets and services
- Explanation
-
This dataset has not been assessed for conformance to the referenced INSPIRE regulation.
- Degree
- false
- Lineage
-
Image processing procedures - The GNSS positions of the images were recorded during the flight. Post-Processed Kinematic (PPK) processing of the image positions was employed to bring the image accuracy to within 10 cm. This was carried out using the UAV control software (eMotion3), with the RINEX correction data from Leica Geosystems base station MACY at: Bro Ddyfi Leisure Centre, Plas Dr, Machynlleth SY20 8ER. The RINEX correction data was provided by HxGN SmartNet. Transformation Conversion from WGS 84, ETRS89 Geodetic to OSGB36/British National Grid was performed using: Ordnance Survey, Grid InQuestII software. The orthomosaic and Digital Surface Model (DSM) were created with Pix4D photogrammetry software, using the provided default settings.
Accuracy - The accuracy of the resulting orthomosaic and digital surface models is dependent on a range of factors, including:
• The height of the camera above the terrain – this varies depending on the ruggedness of the terrain.
• The contrast and detail in the terrain – featureless and uniform vegetation provides fewer opportunities to match points between photographs resulting in lower accuracy • Light levels – imagery flown on a bright day will have sharper images, resulting in more accurate pattern matching and thus registration
• The GPS satellite configuration at the time of the survey
• The proximity of the survey area to the GPS base stations used for applying positional corrections As a result, the accuracy will vary between the sites and within each site. The surveys were generally flown in moderate to good light conditions with the GPS positions post-processed using Leica SmartNet corrections and map projection transformations carried out using Ordnance Survey OSTN15 corrections, so the absolute positional accuracy should be better than 10cm in plan and 15cm in height.
Keywords
Keywords
- Type
- Theme
Citation
- Date (Publication)
- 2008-06-01
Keywords
-
NRW Thesaurus
-
- aerial surveys
- lowland peatlands
- drone survey
- Type
- Theme
Citation
- Date (Publication)
- 2025-01-08
Spatial Reference System
Content
Content Information
NRW Profile
Custom Elements
- NRW Related Title
-
Aerial survey report: Elan Valley
Constraints
Constraints
Limitations on Public Access and Use
- Restriction type
- Other restrictions
Access Constraints Directive
- Limitations
- no limitations
Access Constraints Text
- Other constraints
-
Access restrictions on this data have not been determined. It may contain sensitive information and therefore may be restricted under legislation. NRW may provide access to this dataset on request, however NRW may not release, publish or disseminate the data or derived products freely without further assessment.
Use Constraints
- Use constraints type
- Other restrictions
- Other constraints
-
© CNC/NRW. Data may only be re-used externally under provision and in line with the terms of a NRW licence following an assessment of the data.
Attribution Statement
- Other constraints
-
Contains Natural Resources Wales information © Natural Resources Wales and Database Right. All rights Reserved.
Metadata
Metadata
- File Identifier
- 4f4c4942-4343-5764-6473-313235343037 XML
- Metadata Language
- English
- Resource type
- Dataset
- Metadata Date
- 2025-07-07T15:05:37.646Z
- Metadata Standard Name
- NRW
- Metadata Standard Version
-
1.0