3D-interpolation Clause Samples

3D-interpolation. To estimate a volume we need a 3-D interpolation for the whole glacier. To do this we need to mark the glacier boundary and assign a depth value of 0. Using the boundary, the depth values from the measured profiles and the interpolation lines, we can make an interpolation of the whole glacier. Figure 26 shows the profiles from which the depth calculation was done. The estimated glacier volume was calculated using the mapping and spatial analyst program in ArcGIS. Data from GPR profiles were imported and interpolation lines were made in order to have depth information for as large an area as possible. After merging the GPR profiles, interpolations and glacier boundary (figure 26), the whole glacier can be interpolated. Several tools were used to acquire a good 3D-model. The geostatistical tool enabled us to use a radial basis function to make interpolations between points of known depth. With this tool a sector with four sections, with a 45 degree tilt, was used to optimize the distribution of GPR profiles. Since the glacier changes direction at the middle of the valley , two different interpolation models was made. This was because an average result for both directions combined would give a wrong depth model. The 5×5 grid cells in the two models were transformed into points containing depth information. The gap between the two models was interpolated and the models were merged together (figure 27).