FAQs - Mapping

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From whom is the Aerial Photography imagery sourced and how current is it?

The aerial photography used within the Active Places Power website is supplied via the Aerial Photography for Great Britain (APGB) contract.  This is a contract between Department for Environment, Food and Rural Affairs (DEFRA) on behlaf of a numebr of central government organisation and Getmapping who are the lead supplier for a consortium that includes Bluesky, and Airbus.

The aerial photography is of a high 25cm resolution and is updated on a rolling 3 year cycle.  Although the majority of imagery has been captured within the last three years some areas are older.  

To access the aerial photography when using the interactive maps, go to Map Tools tab > Map Layers > Basemaps and Aerial Photography.

For more information see:

http://www.nextperspectives.co.uk


What contextual base map data is being used within the Active Places Power map component?

The Active Places Power interactive mapping component displays a number of different Ordnance Survey datasets, which are styled and set to display at different zoom levels. They are referenced via an ArcGIS map service hosted by ESRI UK.

Datasets range from MiniScale´┐Ż and 1:250 000 Scale Colour Raster to Vector Map Local (VML) and OS MasterMap thereby providing highly detailed contextual mapping from national to street level. Users can choose between the following basemap styles to provide context to overlaid data.

• 'Grey' – greyscale map with no labels providing the minimal level of contextual detail.  (References the OS_Open_Greyscale ESRI UK Opendata map service.)  Does not display at 1:2,500 or 1:1,250 scales.

• 'Simple' – uncluttered and clean map consistent between all viewing scale.  (References the OS_Open_Background ESRI UK Opendata map service.)  Does not display at 1:2,500 or 1:1,250 scales.

• 'Detailed' – the be comprehensive contextual map showing MasterMap level detail at the largest scales.  (References the OS_VML_MM_Carto ESRI UK Premium map service.)  Default map.  Displays at all scales.

• 'Traditional' – displays Ordnance Survey raster maps including 1:50k, 1:25k and 1:10k at larger scales.  (References the OS_Premium_Rasters ESRI UK Premium map service.)  Does not display at 1:1,250 scale.

Data is updated on a quarterly basis and cached at the following levels:


• 10,000,000
• 5,000,000
• 2,500,000
• 1,000,000
• 500,000
• 250,000
• 100,000
• 75,000
• 50,000
• 25,000
• 10,000
• 5,000
• 2,500
• 1,250

For more information see:
http://www.esriuk.com/content-services/online-content-services/premium-services


What do the map marker balloons / clusters represent?

Active Places Power displays point based data for sport facility locations on the interactive map using balloon shaped map markers.  

To display map markers either run a search or report and swtich to the map tab to view results via a map interface.  Alternatively run a Map Search.  For all map interfaces the Map Tools tab (displayed on the left side of the map) has two sections.  Use Map Search to navigate the map or Map Layers to add and remove map data layers including, individual faciliity types.  

Due to the potential to represent a large number of facilities geographically on a map, a visual representation technique known as clustering is used. 

Clustering reduces the number of map markers displayed on the map by grouping those in close proximity to each other in an aggregate form.  Each map marker cluster contains a summary count of the number of facilities set to display.  

Clustered map marker balloons have four sizes:

• Small – no count represents a single count

• Small – with count represents between 2 to 9

• Medium – with count represent between 10 to 99

• Large – with count represents between 100 to 999

Zooming in to a more detailed large scale map will result in the dispersion of markers into individual marker locations.  The opposite is also true that zooming out to a small scale map will result in markers grouping together.  

Map markers that continue to display a count value at large map scales will represent sites with more than 2 facilities.  

It should be noted that a cluster map marker is generally located at the geographic centre for those dispersed individual locations grouped within the cluster. 

Only when the cluster represents a collection of facilities at a single site or the cluster representation is turned off will the map markers represent the exact geographic location of a site with multiple facilities.