Navmesh Creator

The NavMesh Creator only handles meshes composed of triangles or convex quads. All other meshes will be considered invalid. However, Maya provides a tool that can triangulate any mesh, thus making it useable by the NavMesh Creator. Just select the geometry and use the Maya Polygons / Mesh / Triangulate menu.

 

Also notice that even if the geometry is displayed with a smooth level, the NavMesh Creator will only take into account the base geometry without smoothing.

 

To start using the NavMesh Creator, first select the geometry you wish to transform. You can select any mesh or group of meshes in Maya.

If no mesh is selected a warning will be displayed.

 

This part explains how to configure the navmesh creation 

Creation Type

• Voxel Based Subdivision: this technique creates a voxel mold that approximates the input geometry. The voxels are then used to extract contours around obstacles and around the edges of the world, which in turn are used to create the navigation mesh. The process uses the Recast library (see http://code.google.com/p/recastnavigation/).
  
  This technique is very fast on most environments, especially when increasing the voxel size. On the other hand, the computed navigation mesh is only a loose approximation of the input geometry (depending on the voxel size), and some details like steps will not be preserved. The computation time mostly depends on the size of the environment, and it is not influenced by the topological complexity of it (like the number of triangles, of obstacles, holes, slopes, etc.).

• Exact Subdivision: this technique conserves all the details of the original geometry, which means that the resulting navigation mesh will follow the original geometry very closely (some simplifications will be made when dealing with nearly coplanar triangles). The computation time mostly depends on the topological complexity of the environment and it is not influenced by the size of the environment.

Statistics

Crowd Unit

Crowd Entity Parameters

This tab contains the advanced parameters of the voxel subdivision. They are divided into 3 categories: Rasterization, Regions and Contours.

 

The Rasterization parameters are:

Double Sided Geometry	voxel based subdivision is sensitive to the orientation of the input triangles. Triangles facing down will not be taken into account unless this option is checked.
Voxel Length/Width	this parameter determines the width and length of a voxel. Using bigger voxels reduces computing time but the computed navmesh will also be less precise.
Voxel Height	this parameter determines the height of a voxel. Using bigger voxels reduces computing time but the computed navmesh will also be less precise.
Voxel Count	this label displays the total number of voxels that will be generated from the input geometry, and also the number of voxels along each axis (x, y and z). The voxels count is updated when the voxel length/width, height, or input geometry change.
Tile Length/Width	large environments are divided into square tiles that can be computed individually, thus reducing the memory footprint of the computation. This parameter defines the length and width of each tile, in voxels.
Tiles Count	this label displays the number of tiles along the x and the z axis. The tiles count is updated then the voxel length/width, the tile length/width or the input geometry change.

 

Minimum Region Size	this parameter defines the minimum number of interconnected voxels that are allowed to form isolated areas.
Merged Region Size	regions with a voxel count smaller than this parameter will be merged with other regions if possible.

The contours are the limits between regions. The Contours parameters are:

 

 

Maximum Edge Length	this parameter sets the maximum length of an edge along the borders of the navigation mesh. Edges longer than this value will be split into several edges as needed.
Maximum Edge Error	raw contours are computed as limits between voxels of different regions. These contours are then simplified to reduce the number of edges in the navMesh. This parameter sets the maximum distance a simplified contour's borders should deviate from the original raw contour.

This tab contains the advanced parameters of the exact subdivision.

Keep Only Greatest Connex Zone	if checked, only the greatest (in term of area) isolated portion of the spatial environment will be kept
Minimum Connex Zone Surface	Minimum area (in maya unit²) for an isolated portion of the spatial environment to be kept. It's used when the Keep Only Greatest Connex Zone is unchecked.
Maximum Flat Height	the maximum height at which a step will be considered flat by the crowd entities
Vertices Merge Distance	if two input geometry vertices are closer to each other than this value, they are merged in the computed navMesh
Altitude Precision	if geometry triangle vertices distances to a plane are less that the given value, this triangle is considered coplanar with this plane
Vertical Threshold	if the 2D projection of an original geometry triangle has a minimum height inferior to this value, it is modified to be vertical
Alignment Threshold	given two 2D segments [p1,p2] and [p2,p3], if distance(p2,[p1,p3]) < Alignment Threshold, the three points are aligned
Maximum Horizontal Slope	the maximum angle to which a slope is considered horizontal.
Project Walls Geometry	if checked, the walls geometry is projected when computing the prisms section (might help if some walls are ignored)

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