For contour data with contour spacing of 10, use 5.0 and 100.0.For less dense point data up to 1:500,000 scale, use 10.0 and 400.0.Typical values for the Tolerance 1 and Tolerance 2 settings are: Stream data is a powerful way of adding topographic information to the interpolation, further ensuring the quality of the output DEM. Stream data always takes priority over point or contour data therefore, elevation data points that conflict with descent down each stream are ignored. Representing braided streams or using arcs to represent two sides of a stream may not produce reliable results. At smaller scales it can be just as effective, and less expensive, to digitize corner points of contours and use them as an input point feature class. Contours are best suited for large-scale data where the contours and corners are reliable indicators of streams and ridges. The algorithm then implements the contours as a source of elevation information. When the input feature data type is Contour, the algorithm first generates a generalized morphology of the surface based on the curvature of the contours. The maximum number of points that can be used is NRows * NCols, where NRows is the number of rows in the output raster and NCols is the number of columns. If too many points are encountered by the algorithm, an error may occur, indicating the point dataset has too many points. If more than one input point falls within an output cell, Topo to Raster will use the average value for the interpolation (only the first 100 points that fall within a cell will be considered and the rest will be ignored). Unprojected data (latitude-longitude) can be used however, the results may not be as accurate, particularly at high latitudes. The best results will be obtained if all input data is stored in the same planar coordinate system and has the same z-units. Learn more about how Topo to Raster works Usage "We got expert advice and found out we wouldn't know where that would stop, it would be a mechanical failure and failure and failure," Mr Jane said.Interpolates a hydrologically correct raster surface from point, The next idea was a "mechanical failure" - blasting the cliff to get the fall over and done with.īut the soft rock of the cliffs extends all the way into the township so blasting it may have just pushed the erosion closer to roads and buildings. Netting was considered, similar to the nets covering parts of the cliff along the Great Ocean Road.īut Demons Bluff's soft, almost sand-like rock would just fall through the nets, Mr Jane said, so it was ruled out. GORA's Paul Jane said other solutions were looked at before the decision was made to close the beach. It will fall as a pile of rubble and that rubble will run out right down to low tide so if anyone is there when it goes they're either going to be buried or hit by a pile of rubble." Exploding the cliff considered "I wouldn't want to walk there myself now. "Water is dripping into those cracks and the runoff goes right down to low tide," he said. The chunk measures about 30 metres by five metres, and has a volume equivalent to two Olympic-sized swimming pools. The citizen scientists have watched a crack about 10 centimetres wide grow to 70cm over the past few years, and that part of the cliff "is about to go", Dr Kennedy said. The crack was detected by 10 local citizen scientists who have been monitoring the cliff with drones for three years.ĭavid Kennedy is an associate professor of environmental programs at the University of Melbourne who led the citizen science project and said erosion was what made Demons Bluff so "spectacular".Ī large chunk of cliff collapsed at Demons Bluff in 2019. "As it stands there's a crack that runs for about 60 metres long down the cliff, so if we have a failure anybody under that cliff may be in significant jeopardy," Mr Jane said. Within the past 12 months there have been some significant falls, he said, but an even bigger collapse was approaching. "We certainly don't want to do that, we want to take an approach where we are informing the community, acknowledging the risk and making sure people stay away from the area for their own safety," he said. While he hoped the public would stay away, Mr Jane said the authority would introduce fines if people continued to access the beach. The decision was not an easy one to make, GORA director Paul Jane said.īut after three years of watching a crack in the cliff grow from a hairline to a gaping hole, the risk was too great to keep the beach open. Current cracks show how close the old Surf Coast Walking track is to falling into the ocean.
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