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Guided Workflow | Computing Volumes

Exercise overview

In this exercise, we will see how to:

  • Compute the volume at a certain level of liquid

  • Evaluate the maximum level of a mountain lake

  • Calculate intersections between surfaces

  • Make a “constraint meshing”

The file used in this tutorial is MountainLake.3dr (download).

Calculating the volume of a lake

Open the file MountainLake.3dr.

Determining the maximum water height

The model represents a mountain landscape and the goal is to evaluate the maximum capacity of a mountain lake.

  • Select the object

  • Launch the command Volume From Elevation

  • Set the Direction: X = 0; Y = 0; Z = 1. 

  • Adjust the water height to find the maximum water height. For this, you must zoom to verify that there is no junction here between the inside and the outside of the lake

  • You should find 2339.6 m

  • Press Preview then OK to validate the results

Figure 2: Adjusting the water level to find the maximum capacity of the mountain lake

The result of the volume calculation, here, is not meaningful because it represents the sum of the volumes inside AND outside the lake. Here we need only the volume inside.

Computing the contour of the lake

  • Select both the mountain surface and created plane

  • Launch the command Intersection

  • You should see that the intersection contours are calculated

  • Click OK, Exit to keep the result

  • Select the water level and hide it

Im4Fr.PNG

Figure 3: Using the command Intersection to get the contour of the lake

Separating the lake surface from the rest of the mountain

  • Select both the mountain surface and the contours

  • Launch the command Constraint Mesh

  • Check only Cut in parts

  • Click Preview to calculate the result, and then OK to validate

The mesh has been cut along the contours.

Calculating the volume of the lake

  • Click on the lake and right click to Show only this object

  • Launch the command Volume From Elevation

  • Adjust the water height to be at the maximum water height. You can click on the plus button at the beginning of list of distance, select option Nearest 3D Projection and select point on the top border of the lake.

  • Click OK

  • You should obtain a volume of 5.7 million of m3

Figure 4: Computing the volume of the lake: 5.7 million of m3

Calculating the volume at several levels

It is also possible to compute a liquid volume all over the mesh according to regular levels. The resulting volumes can be displayed through Measure(s) and a customizable report or can be exported in CSV format.

  • Click on the lake and right click to Show only this object

  • Launch the command Volume From Elevation

  • Put the options as below:

    • Direction: X=0; Y=0; Z=1.

    • Choose Regular steps: 1m From 2310 m To 2339.6 m thanks to Custom mode.

  • Click OK

The intersection lines between each plane and the mesh can also be extracted via the command Intersection.

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