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/* General Rules of EM.Cube's Surface Mesh Generators */
# Click the OK button of the dialog to return to the project workspace.
You can change the mesh algorithm from the dropdown list labeled '''Mesh Type''' if there is more than one option. You can also enter a different value for '''Mesh Density''' in cells per effective wavelength (λ<sub>eff</sub>). For each value of mesh density, the dialog also shows the average "Cell Edge Length" in the free space.
== The Triangular Surface Mesh Generator ==
[[EM.Illumina]], [[EM.Libera]], [[EM.Terrano]] and [[EM.Picasso]] use a triangular surface mesh to discretize the structure of your project workspace. All these modules assume an unbounded, open-boundary computational domain, wherein the physical structure is placed against some sort of background medium with infinite extents. It is important to note that only finite-extent surfaces or the surface of finite-extent volumes are discretized. The surface mesh generating algorithm tries to produce regularized triangular cells with almost equal surface areas across the entire structure.
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<td> [[Image:PO2.png|thumb|360px|Two ellipsoids of different compositions.]] </td>
<td> [[Image:PO3.png|thumb|360px|Trinagular surface mesh of the two ellipsoids.]] </td>
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=== Controlling the Resolution of Surface Mesh ===
You can control the average mesh cell size using the "Mesh Density" parameter. By default, the mesh density of [[EM.Illumina]] and [[EM.Libera]] is expressed in terms of the free-space wavelength. The default mesh density is 10 cells per wavelength. This usually creates slightly more than 100 regular triangular cells per squared wavelength. The default mesh density of [[EM.Picasso]] is expressed in terms of the effective wavelength, which takes into account the material properties of a planar structure's substrate layers. The default planar mesh density is 20 cells per effective wavelength. Alternatively, you can base the definition of the mesh density on "Cell Edge Length" expressed in project units. [[EM.Terrano]]'s mesh density is always expressed in cell edge length and its default value is 100 units. This large edge length is intended to create the fewest number of triangular facets on cubic objects with rectangular faces.
You can change the value of '''Mesh Density''' from the Mesh Settings dialog and generate a triangular mesh with a higher or lower resolution.
=== Refining the Surface Mesh Quality ===
Surface mesh generation in [[EM.Cube]] is a two-step process. First, a tessellated version of an object in your project workspace is created. Then, the tessellated object undergoes a surface re-meshing to generate regularized triangular cells. This process is fairly straightforward in the case of flat planar structures. For curved surfaces and curved [[Solid Objects|solid objects]], the quality of the initial tessellation of the object is very important and directly affects the quality of the final surface mesh. You can access some additional mesh [[parameters]] by clicking the {{key|Tessellation Options}} button of the Mesh Settings dialog. In the Tessellation Options dialog, you can change '''Curvature Angle Tolerance''' expressed in degrees, which as a default value of 15°. This parameter can affect the shape of the mesh especially in the case of solid CAD objects. It determines the apex angle of the triangular cells of the primary tessellation mesh which is generated initially before cell regularization. Lower values of the angle tolerance result in a less smooth and more pointed mesh of curved surface like a sphere.
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<td> [[Image:PROP20B.png|thumb|400px|Three building objects with different basic and composite shapes in EM.Terrano.]] </td>
<td> [[Image:prop_manual-29A.png|thumb|320px|The Tessellation Options dialog.]] </td>
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<table>
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<td> [[Image:PROP20C.png|thumb|360px|The default mesh of the three building objects in EM.Terrano with an edge length of 100m and a curvature angle tolerance of 45°.]] </td>
<td> [[Image:PROP20D.png|thumb|360px|The refined mesh of the three building objects in EM.Terrano with an edge length of 10m and a curvature angle tolerance of 10°.]] </td>
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</table>
== General Rules of EM.Cube's Surface Mesh Generators ==
