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Digital Elevation Model (DEM)  
   
Digital Elevation Models are data files that contain the elevation of the terrain over a specified area, usually at a fixed grid interval over the "Bare Earth".
 The terrain elevations for ground positions are sampled at regularly spaced horizontal intervals
 
 
 
 
 
 
 
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STL employs two methods for DEM generation. We use the information from topographical maps at scales from 1:10,000 to 1:250,000 depending on availability and the required resolution to derive DEMs. For those areas where contour maps are not available, we employ high resolution satellite imageries, Aerial Photographs or Land surveying methods to generate spot height data at regular intervals and then use to produce the DEMs.

 
 

DEMs are in either Latitude-Longitude or UTM WGS84. Nigeria spreads across 3 UTM Zones -Zones 31, 32 and 33 projection.  

Data Format

  • Aircom ASSET

  • Planet EV

  • Pathloss

  • ASCII Grid

Data Availability

We have in our archive 50m resolution DEM data covering the entire Nigeria while 20m resolution DEM data is available for over 70 cities. See Map Catalogue 

 

 

 

Quality DEM products are measured by how accurate the elevation is at each pixel and how accurately the morphology is presented. Several factors are important for quality of DEM-derived products:
  • Terrain roughness
  • Sampling density (elevation data collection method)
  • Grid resolution or pixel size
  • Interpolation algorithm
  • Vertical resolution
  • Terrain analysis algorithm

 

 

 

 

Applications
  • Wireless RF Planning
  • Microwave Transmission Planning
  • Ecosystem analysis
  • Fuel spill detection
  • Soil type mapping and analysis
  • Water quality
  • Engineering & Construction 
  • Agriculture
  • Forestry
  • Oil & Gas
  • Roads & Railroads
 

 

 

 
 

 

 

 

       
         
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