I have generated contours in QGIS using point data (AutoCAD file) and I had to also smoothen the contours and remove noises (smaller contours) from the contour generated. I need to get this contour data or DEM for steady flow analysis in HEC-RAS. If I am not wrong HEC-RAS needs DEM (TIFF file) for using RASMAPPER. I, therefore, need to convert this smoothened contour I vector to a TIFF file. How can I do this?
I have seen suggestions regarding TIN interpolation, using GRASS, etc. While using TIN interpolation it just hangs if I do Clough toucher interpolation while linear interpolation gives a result but if I extract contour from it, it's different than the original contour. I am a bit confused if I use contour then should the under "type" should it be a point or breakline or structure? Because when I Used structure or break lines, it didn't work. As suggested in many other answers I tried to use grass. The main problem with GRASS for me is to set the region. It allows only rectangular region but the contour that I have does not fit in a rectangle (I mean if I select rectangle there will be empty areas as the river is meandering). This led to unrealistic contour in those areas. Does anyone have any idea how to select the "Region" in such a case? However, My main issue is to be able to get the smoothened contour vector to a format that can be used in the RAS-mapper. I am new to both QGIS and HEC-RAS.