CloudRF

Online radio planning

User Tools

Site Tools


clutter

Ground Clutter

Clutter or Landcover data is essential for accuracy in RF planning. It describes obstacles above the earth such as trees, buildings or vegetation which are not normally reflected in digital terrain due to the way the terrain is created. LIDAR data is the exception as this contains every obstacle as well as the terrain.
CloudRF supports three different types of ground clutter: Random, Point and Landcover.

Random clutter

The simplest type of clutter is random clutter which is defined as a height in the interface. This height, for example 2 metres, is then applied to the digital terrain to enhance the height evenly around the transmitter. This is easy to implement for broadcasting predictions but lacks accuracy and is not able to differentiate between an urban area or a block of trees for example. A random height of at least 2m is recommended for all calculations to account for vegetation above the earth.

Point clutter

Users can improve accuracy by adding precision clutter above ground level to simulate man made buildings, tree lines and other features not represented by the SRTM data. When an item of clutter is added at a point, it causes the ground height to be increased by the height of the obstacle.
To create custom obstacles, use either the placemark, polygon or line tools within Google earth (or any other KML mapping tool) to make points on the map. Adjust the ‘altitude’ option of the points to set the height of the obstacle. All heights are taken as metres so for a 100ft building, enter 30m.
Once your points have been defined, save off the layer as a kml file, then upload it via the KML upload form linked from the environment section. If correctly formatted, you should see each point listed as a location and height and a report declaring how many were successfully inserted into the database.
Using the newly added clutter can be done by enabling 'Custom clutter' in the environment section.

When creating a clutter layer with Google earth, don't forget to open the properties and set the height!

Landcover clutter

Global Landcover clutter data is available in the system with an accuracy of 0.004 degrees which equates to between 200m and 400m per point dependent on latitude. The MODIS Landcover data has been published for public use by the University of Maryland and is Copyright University of Maryland, Department of Geography and NASA. MODIS data has 17 bands which equate to different types of landcover. CloudRF translates these bands into obstacle heights according to the
ITU-R P.452-11 standard.
ClassTerrainCloudRF height
0 Water0m
1 Evergreen Needleleaf forest20m
2 Evergreen Broadleaf forest20m
3 Deciduous Needleleaf forest15m
4 Deciduous Broadleaf forest15m
5 Mixed forest15m
6 Closed shrublands4m
7 Open shrublands2m
8 Woody savannas4m
9 Savannas2m
10 Grasslands2m
11 Permanent wetlands0m
12 Croplands2m
13 Urban and built-up20m
14 Cropland/Natural vegetation mosaic2m
15 Snow and ice0m
16 Barren or sparsely vegetated0m

clutter.txt · Last modified: 2016/09/01 21:45 by alex