Rolta Automatic Elevation: Automatic Extraction of Digital Terrain Model (DTM) Elevation Points from Digital Aerial / Satellite Stereo Images

Rolta offers a solution for achieving a high degree of automation through the use of hierarchical image data structures and image processing methods on the fly.

Image correlation is used to extract matching pixels in two overlapping images as well as the sensor geometry from a computed math model to calculate x, y, and z positions. Automatic DEM extraction allows users to batch epipolar generation and DEM extraction process, geo-code DEMs, as well as create absolute or relative DEMs. Stereo pairs are re-projected, ensuring that the left and right images have a common orientation, and matching features between the images appear along a common X-axis.

Key Features

  • Generates DTM points in a model; object, or user defined co-ordinate system
  • Generates DTM points from colour or black and white imagery
  • Captures satellite DTMs using Rational Function
  • Performs batch processing
  • Enhanced matching algorithms
  • Optionally suppresses grid points near break lines
  • Explodes borderlines to avoid edge effects
  • Ability to process within clip region – depending on area of interest
  • Ability to set DEM detail to high, medium, or low


  • Yields extremely reliable DTM points because of high redundancy
  • Generates reliable DTM points in an efficient manner
  • Creates robust DTM data (detects blunders, single houses, and trees)
  • Uses flexible user interface with DTM collection for setting parameters, and digitizing point and linear features as necessary
  • Reduces collection time by defining collection areas and skipping excluded areas
  • Monitors the matching of DTMs to detect poor textured areas and modify setup parameters
  • Various DEM editing tools made available to erode holes, interpolate failed values, smooth the DEM and restrict the editing area, as well as help improve DEM quality
  • Epipolar pairs increase the correlation process speed and reduce the possibility of incorrect matches