Consistent mesh

[Paul_Wintour]

Is there a way that I can take a surface and create a uniform mesh from it. The MeshToolKit doesn’t appear to let me do it. It says that it is controlled by Dynamo’s render precision which isn’t accurate, more of a global control. I want to be able to create a room (possibly irregular), generate a surface from it and convert it to a mesh at say 500x500mm resolution. Is this possible? Using UV subdivide is a bit painful because you need to work out the bounding box or ALL rooms. Was hoping for a similar method.

There was something similar discussed here but its not exactly the same issue: Custom Meshes

Thanks

[Dimitar_Venkov]

I don’t believe there’s anything like that for Dynamo. You could go for the average point approach and subdivide the surface until all resulting triangles’ areas are under a target area but the result won’t be very uniform. Vikram has posted one possible way on how to do that here:

How to get triangular meshing on polygonal surfaces

The below definition should sub divide any polygonal surface into as many triangular sub surfaces as the number of sides of the polygon. File: Triangulation.dyn The density of the triangulation can be increased by applying the function (TriDiv) again (…and again…) on the results obtained (The list might need to be flattened, though) [20150629-2]

This is what you can expect with that approach:

[Vikram_Subbaiah]

The below approach should work in cases where points generated using Surface.PointAtParameter are all within the surface.
MeshFromSurface.dyn (6.9 KB)

[Andrew_Hannell]

In Dynamo, you could take a grid of points and project them down onto a surface, and then use these points to generate a mesh.

(I don’t quite understand what you mean by using a room)

It probably does not help you, but I have done something similar but using Civil3D- since it has in built tools to create grids of points from a surface. You can then bring this into Revit as a nice tidy topo, without loads of weird triangulation. (Although it looks neater, it is less efficient and less accurate)

[Vikram_Subbaiah]

@Dimitar_Venkov Like the animation
Don’t think it will impress @Paul_Wintour though

[Paul_Wintour]

Thanks for the response. Not exactly what I had in mind. I would prefer quads as much as possible. The projection method could work but for many surfaces I would imagine it would get very heavy/slow. i guess too that there is no way to ensure that when projecting you will hit the edges and corners of the surface.

Issue: Sunlighthours analysis test points

[Vikram_Subbaiah]

@Paul_Wintour

I would prefer quads as much as possible

@Paul_Wintour The definition provided with my post above converts a surface to a mesh (with quads) where the density of the quads can be controlled. (The limitation is that it only works with rectangular surfaces)
Here is a screenshot that highlights this aspect …

//Dividing surface and grouping points
pnts1=srf.PointAtParameter((0..1..#nU)<1>,(0..1..#nV)<2>);
pnts2=List.DropItems(List.Sublists(pnts1<1>,0..1,1)<1>,-1);
pnts3=List.DropItems(pnts2,-1);
pnts4=List.Reverse(List.DropItems(pnts2,1)<1><2>);
pnts5=List.AddItemToFront(pnts3<1><2>,pnts4<1><2>);
pnts6=List.Flatten(Flatten(pnts5<1><2>),1);
quads=Polygon.ByPoints(pnts6);

//Index Groups
indx=Transpose(IndexOf(Flatten(pnts1),pnts6<1><2>));
indGrp=IndexGroup.ByIndices(indx[0],indx[1],indx[2],indx[3]);
msh=Mesh.ByPointsFaceIndices(Flatten(pnts1),indGrp);

[Paul_Wintour]

Hi Vikram

I need to be able to extract room polylines, convert them to a surface and then turn it into a quad mesh. So the workflow needs to be able to accept irregular shapes.

[Vikram_Subbaiah]

@Paul_Wintour Should be able to alter the code to accept irregular shapes.
Curved edges might end up being segmented, though.
Will work on it.

[Vikram_Subbaiah]

@Paul_Wintour

the workflow needs to be able to accept irregular shapes

@Paul_Wintour This should work with irregular shapes.
MeshFromSurface-1.dyn (6.1 KB)

//Dividing surface and grouping points
pnts1=srf.PointAtParameter((0.00001..0.99999..#nU)<1>,(0.00001..0.99999..#nV)<2>);
lins1=Line.ByStartPointEndPoint(List.FirstItem(pnts1),List.LastItem(pnts1));
lins2=lins1.Intersect(srf);
pnts3=Flatten(lins2)<1>.PointAtParameter(0..1..#nU);

pnts4=List.DropItems(List.Sublists(pnts3<1>,0..1,1)<1>,-1);
pnts5=List.DropItems(pnts4,-1);
pnts6=List.Reverse(List.DropItems(pnts4,1)<1><2>);
pnts7=List.AddItemToFront(pnts5<1><2>,pnts6<1><2>);
pnts8=List.Flatten(Flatten(pnts7<1><2>),1);

//Index Groups
indx=Transpose(IndexOf(Flatten(pnts3),pnts8<1><2>));
indGrp=IndexGroup.ByIndices(indx[0],indx[1],indx[2],indx[3]);
msh=Mesh.ByPointsFaceIndices(Flatten(pnts3),indGrp);

[Michael_Kirschner]

@Keith_Alfaro1

[Paul_Wintour]

Hi Vikram
Isn’t this a UV subdivide which results in irregular sized mesh faces? I’m trying to ensure the faces are all (more or less) the same size.

[Vikram_Subbaiah]

@Paul_Wintour

Isn’t this a UV subdivide

I thought it was, but Dynamo doesn’t seem to think so (not always, at least). And I’m not sure anymore

@Paul_Wintour Upload a sample sketch of a simple irregular surface with a rough pattern.

[Paul_Wintour]

Hi Vikram. Mostapha from Ladybug has been working on the creating a consistent mesh from a surface. I haven’t had a chance to test it out yet.

Issue: Sunlighthours analysis test points

[inleiva]

Hi @Vikram_Subbaiah! The code is great, but I have a question. How can I modify it to get a more regular mesh in the case of a pentagon? If I do it with this code, this happens.