挖空 3D 网格

Question

有一篇文章介绍了 MeshLab 如何挖空由三角形多边形组成的 3D 网格。基于那篇文章，我的理解是 MeshLab 方法是：

创建一个从模型网格重新采样的新偏移网格
1. 建立统一的体积表示，即体素
   每个体素包含距原始表面的有符号距离
   使用
   3. 行进立方体算法构建重采样表面
   需要输入偏移量
翻转法线向量以获得新的偏移网格
合并原始网格和新的偏移网格

问题

这是镂空3D模型的唯一方法吗？有哪些替代方法？

MeshLab UI 镂空

MeshLab 方法如下所示：

MeshLab 脚本

这是用于挖空 3D 模型的 MeshLab 脚本：

<!DOCTYPE FilterScript>
<FilterScript>
 <filter name="Uniform Mesh Resampling">
  <Param type="RichAbsPerc" max="22.4008" isxmlparam="0" name="CellSize" tooltip="Size of the cell, the default is 1/50 of the box diag. Smaller cells give better precision at a higher computational cost. Remember that halving the cell size means that you build a volume 8 times larger." value="0.44802" description="Precision" min="0"/>
  <Param type="RichAbsPerc" max="4.48016" isxmlparam="0" name="Offset" tooltip="Offset of the created surface (i.e. distance of the created surface from the original one).&lt;br>If offset is zero, the created surface passes on the original mesh itself. Values greater than zero mean an external surface, and lower than zero mean an internal surface.&lt;br> In practice this value is the threshold passed to the Marching Cube algorithm to extract the isosurface from the distance field representation." value="-0.179206" description="Offset" min="-4.48016"/>
  <Param type="RichBool" isxmlparam="0" name="mergeCloseVert" tooltip="If true the mesh generated by MC will be cleaned by unifying vertices that are almost coincident" value="false" description="Clean Vertices"/>
  <Param type="RichBool" isxmlparam="0" name="discretize" tooltip="If true the position of the intersected edge of the marching cube grid is not computed by linear interpolation, but it is placed in fixed middle position. As a consequence the resampled object will look severely aliased by a stairstep appearance.&lt;br>Useful only for simulating the output of 3D printing devices." value="false" description="Discretize"/>
  <Param type="RichBool" isxmlparam="0" name="multisample" tooltip="If true the distance field is more accurately compute by multisampling the volume (7 sample for each voxel). Much slower but less artifacts." value="false" description="Multi-sample"/>
  <Param type="RichBool" isxmlparam="0" name="absDist" tooltip="If true a &lt;b> not&lt;/b> signed distance field is computed. In this case you have to choose a not zero Offset and a double surface is built around the original surface, inside and outside. Is useful to convrt thin floating surfaces into &lt;i> solid, thick meshes.&lt;/i>. t" value="false" description="Absolute Distance"/>
 </filter>
 <filter name="Invert Faces Orientation">
  <Param type="RichBool" isxmlparam="0" name="forceFlip" tooltip="If selected, the normals will always be flipped; otherwise, the filter tries to set them outside" value="true" description="Force Flip"/>
  <Param type="RichBool" isxmlparam="0" name="onlySelected" tooltip="If selected, only selected faces will be affected" value="false" description="Flip only selected faces"/>
 </filter>
 <filter name="Flatten Visible Layers">
  <Param type="RichBool" isxmlparam="0" name="MergeVisible" tooltip="If true, flatten only visible layers, otherwise, all layers are used" value="true" description="Merge Only Visible Layers"/>
  <Param type="RichBool" isxmlparam="0" name="DeleteLayer" tooltip="Delete all the layers used as source in flattening. &lt;br>If all layers are visible only a single layer will remain after the invocation of this filter" value="true" description="Delete Layers "/>
  <Param type="RichBool" isxmlparam="0" name="MergeVertices" tooltip="Merge the vertices that are duplicated among different layers. &#xa;&#xa;Very useful when the layers are spliced portions of a single big mesh." value="true" description="Merge duplicate vertices"/>
  <Param type="RichBool" isxmlparam="0" name="AlsoUnreferenced" tooltip="Do not discard unreferenced vertices from source layers&#xa;&#xa;Necessary for point-cloud layers" value="false" description="Keep unreferenced vertices"/>
 </filter>
</FilterScript>

Answer 1

另一种方法是： 均匀采样 -> 绝对距离 -> 添加

正偏移量