stl model thickens or offsets outward

[zrggci]

I want to thicken stl model outward, but thickenMesh function or offsetMesh function is not useful. Beacuse they not only thicken or offset outward , but also they thicken or offset inward. What should I do to achieve the stl model only thickening outward？

[zrggci]

The above figure shows the implementation effect of thickenMesh function or offsetMesh function

[Fedr]

Hello and thanks for the question.

MeshInspector/MeshLib can make offset in one direction only as shown in the video: https://www.youtube.com/watch?v=XXGoLIKy4Rg

In the parameters of thickenMesh call please specify:

params_.signDetectionMode = MR::SignDetectionMode::Unsigned;

If you still have issues with thickening, please upload your input model and we will look at it.

[zrggci]

uniteCloseVertices function has not exposed

[Grantim]

We have exposed uniteCloseVertices and it will be available in our next release, so this code will work for you:

from meshlib import mrmeshpy
nonClosedMesh = mrmeshpy.loadMesh("cai.stl")

# fix disconnected boundary issues
mrmeshpy.uniteCloseVertices(nonClosedMesh, nonClosedMesh.computeBoundingBox().diagonal() * 1e-6)

# thicken
thickness = 2
params = mrmeshpy.OffsetParameters()
params.voxelSize = 1
params.signDetectionMode = mrmeshpy.SignDetectionMode.Unsigned
shell = mrmeshpy.thickenMesh(nonClosedMesh, thickness, params)

# stitch boundaries 
holes = shell.topology.findHoleRepresentiveEdges()
assert holes.size() == 2
newFaces = mrmeshpy.FaceBitSet()
stitchParams = mrmeshpy.StitchHolesParams()
stitchParams.metric = mrmeshpy.getMinAreaMetric( shell )
stitchParams.outNewFaces = newFaces
mrmeshpy.buildCylinderBetweenTwoHoles(shell,holes[0],holes[1],stitchParams)

# subdivide new fases
subdivSettings = mrmeshpy.SubdivideSettings()
subdivSettings.region = newFaces
subdivSettings.maxEdgeSplits = 10000000 # could be INT_MAX
subdivSettings.maxEdgeLen = 1
mrmeshpy.subdivideMesh(shell,subdivSettings)

# smooth new faces
mrmeshpy.positionVertsSmoothly(shell,mrmeshpy.getInnerVerts(shell.topology,newFaces))

mrmeshpy.saveMesh(shell, "thicken.stl")

[zrggci]

Thank you very much for your help,and thanks for every timely response.

[zrggci]

I have recently encountered a more complex problem: the stl model has multiple holes, which may be incomplete, and there are a few scattered triangular patches. The original offsetMesh function was very compatible, but the above code cannot achieve this.

[zrggci]

my model
thicken.zip

[Grantim]

Hello!

There are several problems with input mesh that make it much harder to process with this workflow:

1. There are some small components

2. Also there is tie on one of the holes that prevent good thickening

3. Also there are overlapping faces on the boundary

1 can be fixed automatically
2 and 3 can be fixed manually in MeshInspector App

To run automatic workflow robust and smoothly it is better to fix previous steps steps that created these issues.

Lets suggest that input mesh was OK (for example I've fixed it manually)

Thicken

Process two biggest holes

Process two closest holes

Process last two holes

---

So this case has two general challenges:
1 - fix input mesh that is hard to do automatically and better to fix on previous steps
2 - map holes for processing, that can be done by geometry and positions of the holes

output.zip

[Grantim]

Unfortunately now we don't have easy way to do this, one thing you can do is thicken( square.stl )-> remove base component-> thicken( result ) this way you will thicken to one side, and then thicken back, so you will generate regular mesh at place of original mesh

[zrggci]

remove base component

how do I set the parameters, use python ?

[Grantim]

from meshlib import mrmeshpy as mm

coords = list()
with open("edge_points.txt", "r") as filestream:
	for line in filestream:
		currentline = line.split(",")
		for s in currentline:
			if s:
				coords.append( float(s) )

conts = mm.Contours2f()
conts.resize(1)
conts[0].resize( int(len(coords) / 3) )
for i in range(len(conts[0])):
	conts[0][i] = mm.Vector2f( coords[i*3],coords[i*3+1] )
if conts[0][0] != conts[0][len(conts[0])-1]:
	conts[0].resize(len(conts[0])+1)
	conts[0][len(conts[0])-1] = conts[0][0]

mesh = mm.triangulateContours(conts)
mm.saveMesh(mesh,"outMesh.mrmesh")

def filterComponents( mesh ):
	comps = mm.getAllComponents(mesh)
	lastId = mm.FaceId(mesh.topology.getValidFaces().size() - 1)
	for i in range(len(comps)):
		if comps[i].test(lastId):
			mesh.deleteFaces(comps[i])
			mesh.pack()
			return mesh

thickness = 2
params = mm.OffsetParameters()
params.voxelSize = 1
params.signDetectionMode = mm.SignDetectionMode.Unsigned
thicken = mm.thickenMesh(mesh, thickness, params)

filtMesh = filterComponents(thicken)

thicken2 = mm.thickenMesh(filtMesh, -thickness, params)

resMesh = filterComponents(thicken2)
mm.saveMesh(resMesh,"resMesh.stl")

Something like this

[zrggci]

Thanks for your help! I use the square.stl model to try these code, and find that two thickenfunctions can make the unsmooth edge,so I would like to use a thicken and filterComponentsfunction, then make the z value of the vertices zero becase the square.stl model parallel to the xy plane.

[Grantim]

Sure that will work too