I recently asked a question about trying to calculate the slope over distance (manually) using QGIS, but then I came up with another way of solving the problem, but I would have to get some help for that as well (Sorry, new to open source GIS).
Can I calculate the value difference between adjacent cells, and if the condition is met (e.g. Cell A-Cell B => 1) the cell is given a value of 1, and if false, a value of 0? Or just a color map with intervals of values? This calculation would have to be repeated until every cell is compared with its connecting cells. Does this make any sense? I have latest QGIS with GRASS and gdal, and I also use SAGA. Thanks Fredrik