any fast ways to removethe useless edges?

[brian661]

I have a scene with a lots of building exported as wrl from other software, 

and most of the building are built in triangles, 

like the following image

For some of the building, like the most right one in the image,

there are lots of unnessary edges/vetices.

Are there any fast ways to remove those?

It is impossible for me to remove there building by building.

[Stefan_L · Accepted solution]

Doing archviz with imported models from CAD this is my bread and butter 🙂

- apply one Edit Mesh modifier for all objects,

- if necessary weld all vertices (hit 1 for Vertex subobject, CTRL-A, tune threshold, hit Selected),

- hit 2 for Edge subobject level, CTRL-A, hit Auto Edge in Surface Properties section (tune angle value if needed)

- hit 2 again to exit subobject level

If you want to go on working, collapsing the modifier in the stack list sometimes moves the objects all around.

You'd better rightclick in viewport and hit Convert to: Editable [something], whatever you prefer.

[brian661]

Thanks for your reply.
I have select the object-->add a edit mesh modifier-->hit 2 and ctrl+a to select all edge
but auto edge seem not working on it
not matter I set it as 10 or 100
The edge are still appearing.
Do I miss and set something wrong?

[PROH]

Sounds like the vertices aren't welded. Open edges will always be visible using "auto edge".

Hope it helps

[Stefan_L]

Yes, as said in post #2 the vertices have to be welded.

Otherwise you have two open edges between the faces, so they won't be hidden.

Assuming the vertices are very close together, I'd start with a threshold of 0.0001 (I usually work in meters).

Hit 1 for Vertex subobject, CTRL-A, tune threshold, hit Selected, have fun 🙂

[brian661]

the auto edge works finally

While the edge just become a dotted line

What this means?

[Stefan_L]

Invisble edges are shown as dotted lines when selected. They still exist, but are not shown when deselected.

Regarding the black faces:

Thats either the smoothing groups which are messed up or the face normals.

Select object, hit 3 for face subobject level, CTRL-A, hit Auto Smooth.

If it's still splotchy I'd check the normals:

Select object, hit 3 for face subobject level, CTRL-A, activate Show Normals under Selection (first section), tune Scale.

You should see blue lines beginning at the center of each triangle, pointing outwards the object. If some are pointing inwards, you can try Unify in Surface Properties section.

[Steve_Curley]

All models are made of Triangles, in some cases they're "hidden" from view. Under certain circumstances the "hidden" ones can be displayed as dotted lines.
Right-click the object > Object Properties > Edges Only (turn it on).
If that doesn't work, which viewport renderer are you using? If it's Legacy Direct3D then there is an option in the setup for that to "Display All Triangle Edges" (turn it off). Warning - the D3D settings are saved in the program folder - under Program Files. If you don't have permission to write in there the setting will not stick - you'll lose it next time you open Max.

[brian661]

I see, so do the auto edge reduce the total face?

(I beleive not as I just turn 2 triangle into one retecangle, and it is still 2 triangle, isn't it?)

If not, in oreder to reduce the total face, 

it that means what I have to do is reduce the unnessary vetices?

[Stefan_L]

The visibility of an edge has no impact on face count.

But it's a bit more than just seeing it or not, e.g. you can define Polygon subobjects by hiding internal edges. Your picture in post 6 shows one Polygon which consists of ten Faces. (IMHO it shoud be two polygons; the 3rd vertical edge from left should be visible 🙂 ).

Once you have a Polygon (which doesn't need to be flat BTW), you can easily select it, extrude it, put another material on it, whatever...

To get rid of the unnecessary vertices you can either move them by hand onto another adjacent vertice (use snapping!) and weld them, which can be quite a pain in the rear.

Or you rely on the built in rocket science of 3dsMax; there are two modifiers called Optimize and ProOptimizer. In this case the simple Optimize seems to be the appropriate tool.

[felix]

For standard edge + vertex removal I always use Editable Poly´s feature "Remove" in the "Edit Edges" section. This wouldn´t remove the vertices either though, reason after having deleted the edges I change to vertex mode, select the redundant vertices and click "Remove" in the "Edit Vertices" section. This will completely remove edges + vertices, reducing the polycount accurately compared to Optimize.

It´s important to first remove the edges and then the vertices afterwards because if you delete the vertices first it will aswell delete edges you like to keep.

A tip (maybe not that important in your case because the edges are aligned differently) is to first "shift-select" one of the to be removed vertices so it will auto-select the rest of the vertices on the edge in line. Keep the vertices selected, change to edge-mode and delete the edges. When you now change back to vertex-mode, all previously selected vertices are still/already marked, so you can then simply click "Remove". Reason doing it this way is because once having deleted the edges the "shift+select" feature wouldn´t have an effect on vertices anymore due to missing edges and selecting would be more complex.

[lightcube]

Agreed. I would use Editable Poly instead of Editable Mesh... especially because of the Remove functions mentioned in Felix's post.

I have a function specifically for scenarios like this in a tool called Carver. In the tool is a button called Fix Coplanar. It automates the steps of finding coplanar faces and removing the edges that make extra faces between the coplanar faces and then removes leftover unnecessary vertices that belonged to those edges.

That function in Carver only works on Editable Poly.

[lightcube]

Actually... it looks like I need to update the docs/screenshots on the Exchange Apps site as they do not contain info on the Fix Coplanar function. And since I cannot edit the post above, here is a link to more robust and up-to-date Carver docs.

[darawork]

Hi,

Bumping this as it's so handy. I forgot how to do this.
Thanks again @Stefan_L 

Regards,