Welds vertices of an sfmesh or IndexSurface object where the spatial distance and texture coordinate difference between vertex pairs are both within the specified threshold, then removes the duplicate vertices.
Syntax
sfmesh ST_3DRemoveDuplicateVertex(sfmesh sfmesh, float8 dist_threshold);Parameters
| Parameter | Description |
|---|---|
sfmesh | The sfmesh model object. |
dist_threshold | The distance threshold. Vertices within this distance of each other are welded into a single vertex. Distance is measured in the Cartesian coordinate system. Both the spatial distance and the texture coordinate difference must fall within this threshold for welding to occur. |
Return value
Returns the welded sfmesh object.
How it works
The function evaluates each pair of vertices in the sfmesh or IndexSurface object against dist_threshold. A vertex pair is merged when both conditions are met:
The Cartesian spatial distance between the two vertices is within
dist_threshold.The texture coordinate difference between the two vertices is within
dist_threshold.
When both conditions are satisfied, the two vertices are welded into one, reducing the total vertex count and the resulting object size.
Effect of dist_threshold on output size
The following sketch maps show how dist_threshold affects output size and geometric detail. A higher threshold merges more vertices and reduces file size, but may cause loss of geometric detail.
Raw data (50.2 MB)
Vertex-welded results (20.2 MB): dist_threshold = 0.01
Vertex-welded results (3.3 MB): dist_threshold = 0.1
Vertex-welded results (0.63 MB): dist_threshold = 1 (some details lost)
Examples
Example: Remove vertices that are close in both spatial position and texture coordinate
The input contains six vertices, some of which are within 0.1 units of each other. After welding, duplicate vertices are merged and the output contains only four distinct vertices.
SELECT ST_AsText(ST_3DRemoveDuplicateVertex('MESHGEOM(PATCH(INDEXSURFACE(VERTEX(0 0 0, 1 0 0, 0 1 0, 1 0.01 0, 0.01 0 0, 0 -1 0), INDEX((0,1,2),(3,4,5)))))'::meshgeom, 0.1));Expected output:
{"version" : 1, "root" : 0, "meshgeoms" : ["MESHGEOM(PATCH(INDEXSURFACE Z (VERTEX(0 0 0,1 0 0,0 1 0,0 -1 0),INDEX((0,1,2),(1,0,3)))))"], "primitives" : [{"meshgeom" : 0}], "nodes" : [{"primitive" : 0}]}