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and pick two existing points, for example create these two new lines:
In some parts, there may be needed some extra point to create the desired line, it is possible to force the division of a curve 'close to a coordinate' using
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Then, it is possible to use the new created point to create a new line:
Note: when selecting the 'near point' it is possible to click the right-mouse button to open the contextual menu, and select other options, like 'Point in line' to pick a point over a curve, like the one to be divided.
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And select the boundary curves.
With this procedure, we can create the three surfaces of the image. The surfaces will have only C0 continuity between them (normals between them are discontinuous), but the shape could be good enough to generate a surface mesh valid for some simulations (see the mesh of the image above).
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Then you can delete unwanted parts
This allow for example to create a 3D volume box for CFD simulations of the air around the topography.
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For instance, sub-sampling with increment=2 will take into account one of each 2 point data in each direction, like shown in the figure hereafter.
Grid from Internet
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