QGIS is great. One of the truly good open source projects. I used it to successfully extract 3D height data for the mountains next to my hometown. This was not an easy task since the miuntains are on a national border and I had to combine height data from two national sources. It still worked out perfectly fine.

in france the lidar collection of data is almost entirely done, we can get numerical model of the terrain and tree heights, it's awesome in qgis!