Wavelet thresholding is used to generate simplified terrain models. This non-linear filtering technique is adaptive in the sense that the large wavelet coefficients in areas of high relief are kept, whereas all coefficients smaller than a threshold value, representing smooth areas, are thrown away. The degree of detail in the simplified model is controlled by the number of wavelet coefficients retained. Two different areas are analysed using this method. The experiments show the smoothing effect of the thresholding, and how the main terrain features survive as the threshold value increases. At large threshold values the method introduces blocking artifacts in the model.