DTM Modelling in n4ce Professional
Modelling can be separated in Features and DTM's. Both give a different representation of the ground surface. In this section, we will be looking at some advanced DTM options introduced in the Professional edition of n4ce.
Feature strings are very important in n4ce, as they perform a number of different functions and add structure to a model. They can be used to isolate areas (boundaries), provide seeding for other design strings like carriageways, bench and batter or be an entity in themselves like centrelines with chainages. They are used in creating designs and more importantly here to force Break Lines into a DTM. This is set up in the code table.
Gridded models can be generated in n4ce, but here we are more likely to be importing data from sources such as Lidar and keeping this in its native grid format for rapid data access and mass data storage. Whilst the Grid model is becoming more prevalent, the most universally accepted surface type is created from a series of non-overlapping triangles. In n4ce, we use a modified Delauney triangulation to achieve this.
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Groups were introduced with the Lite edition and are very useful when calculating areas and volumes or creating visual effects, like shown above. This is from a beach survey showing movement of materials from one year to another.
When calculating volumes between two DTMs an intermediate height difference surface, called Isopachyte, is created. Intersecting triangles and points from both surfaces are used to calculate thickness's automatically recognising break lines and common boundaries from both surfaces. This is called a complex projection. With Group Depths in the Professional edition, volumes can be calculated to the underside of contruction, or formation levels.
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The DTM menu in Professional edition has a number of useful additions over Lite. This includes Boundary which allows you to save and recall boundary strings allowing further contraints to be added to DTMs.
Additional DTM edits include Deletes, Inserts and Forcing.
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During the creation of the DTM, both feature codes and DTM Settings are considered. The latter control long thin triangles around the boundary. A useful option allows you to flood fill triangles and is helpful during deletes to see holes in your DTM.
A report shows how the triangulation process has performed and identifies possible inconsistencies like duplicate points and crossing constraints. The DTM Errors can be plotted on the Dedicated CAD Backcloth and used for editing the DTM.
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Also included in the Features menu is an option to generate a zero isopachyte, or interface string between two DTMs.
A special feature when modelling with the Professioanl edition is called Associates and keeps track of your DTM's and is helpful when taking sections or viewing multiple models in 3D. |
