I was wondering if there is a way to make an Autocorrelated DEM within QGIS or Grass. I am looking to do this with stereo aerial photography. I am able to do this with a number of COTS tools, but I am looking for an open source solution. If you know of other tools I am open to suggestions.
Autocorrelation is achieved by software 'matching' pixel for pixel from each of the image stereopairs. The diff XY co-ords of each, compared to their neighbours, are used to determine elevation variations.
The quality of the result varies, depending upon the scale of the source imagery, the quality & resolution of the sensor, the type of terrain it covers.
SocetSet (BAE), Imagestation (Intergraph), Match T (Inpho), LPS (Er4das) and UltraMap (Microsoft) are recognised s/w suites that include autocorrelation modules. However they are not stand-alone & with required base modules, cost an arm & a leg, and used only by professional geophysical/mapping organisations. Speed of the process is largely dependent upon the resolution required.
Autocorrelation can't 'see through' trees, will follow the contours of buildings. bridges etc. - i.e. good for orthoimage production.
Each of the above s/w suites include tools that enable quite smart filtering of much of the above 'artifacts', and manual tools for further editing (stereo-breaklining) and other refinements where a pure terrain surface is required (i.e. contours, volumetrics etc.).
Not sure what you are exactly looking for but check this module:
It creates a fractal surface of a given fractal dimension.