Full Version: Using a Surface as a Framework

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Hi Andy, there are a couple of different methods you could try to see what you like best.

One way is to use the View >CPlane tool to set the construction plane to a spot on the surface where you want to construct. That will relocate the drawing plane and all the ortho (top/front/right) views to be centered and oriented around that area so when you draw you'll be drawing in that local coordinate system:
https://moi3d.com/4.0/docs/moi_command_reference5.htm#cplane

The other way you can do it is to create a part aligned with the regular world coordinate system and then use the Transform > Orient command to move and rotate it into place on the surface:
https://moi3d.com/4.0/docs/moi_command_reference8.htm#orient

- Michael

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Thanks Michael.

Is there a way to make the display of the mesh a bit easier to work with? There are lots of triangles so it looks like a big, thick mess of black lines. Perhaps thin and light grey?

Andy

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Message 10284.5 was deleted

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View right
Separate the "red object"
Boolean with the box (Will works also with a simple rectangular face )

But your original object is some special very intricated itself! :)

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Another one - I think my surface is too complex for MoI to work with easily. I can't extrude it. I've tried two ways to get it into MoI - use the obj to 3DM converter and the obj import in V4.

Here is the file:

https://www.dropbox.com/s/53srfylmixf1zay/SurfTest.3dm?dl=1

Is there a way to simplify it to an approximation so there are less facets?

Thanks, Andy

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Thanks. I deleted my post because I thought the surface wasn't really a surface, just a collection of lines with no faces, so my mistake. I was trying to see if I could get an indentation into the block using the surface.

Andy

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error 400 for file ! use the loading system of the forum...or check your send... ;)that'

ELse you can erase the box

Planar the "rectangle surface"

make the Trim

that works even with your first file

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Pilou, you are too quick! :) Try now. Andy

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Hi Andy,

re:
> Is there a way to make the display of the mesh a bit easier to work with? There are lots of triangles so it looks like
> a big, thick mess of black lines. Perhaps thin and light grey?

MoI is not designed to work with triangle mesh geometry so it might be difficult to use it in this way.

But you might try using Edit > Lock to lock the mesh so it's not selectable and then it will be grey.

If you want thinner lines, try going to Options > General > "Edit .ini file" button and in the moi.ini file set:
UseThinAntiAliasing=y

- Michael

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For a simplication with less faces, you coukd use :
- Meshlab
- instant meshes

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Hi Andy,

re:
> Another one - I think my surface is too complex for MoI to work with easily. I can't
> extrude it. I've tried two ways to get it into MoI - use the obj to 3DM converter and
> the obj import in V4.

The problem is you don't have a CAD surface, it looks like you have polygon mesh data in the form of triangles.

The OBJ import in MoI V4 is for converting a sub-d control cage into a CAD surface, your mesh looks like it is not configured as a sub-d control cage where it should be a sparse control cage made up of quad polygons.

MoI and other CAD programs in general are not designed to work on this kind of dense triangulated data.

You will probably need to use a polygon mesh editing program to work on this type of data, not a CAD program. I'd recommend trying 3D Coat or ZBrush to start with.

To work with it in CAD you would probably need to go through a process called "reverse engineering" that fits spline surfaces to dense triangle mesh scan data. it's a complex process with pretty expensive tools like Geomagic Wrap for example. It's also possible to approach it with a polygon modeling toolset where it's called "retopology". There are retopo tools in many polygon mesh editing programs again like 3D Coat.

MoI is just not the right tool to work directly on the kind of data you have there.

- Michael

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Thanks Michael - I understand that. What I want to do is use the surface as a scaffolding to work on top of to create NURBS shapes. I don't want to change the surface unless I have to because it's the reference.

Is that doable?

Andy

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Something you can try

Draw a SOlid plane where you want the Trim

Make a Boolean "Merge"

Then Press Tab and write ExplodeMove

your 2 parts will be well separated

As your file is a lot of very pieces...maybe that take a no reasonable time!

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OK, I have now tried this:

1. object obj in meshlab
2. Go to Filters -> Remeshing, Simplification and Reconstruction -> Simplification: Quadric Edge Collapse Decimation
3. Enter target of 1000 faces
4. Export
5. Use Michael's obj23dm converter, choose closed polygon for each face
6. Load into MoI

OK, looks good. A lot less clutter. But the "surface" is just a collection of triangles (closed curves) and there are no faces.

So what I want to do now (for example) is create a NURBS surface over the top, maybe just part of it, and then extrude that. But how?

Thanks, Andy

Attachments:
mesh-simplified.3dm

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HI Andy,

> Is that doable?

Not really, at least not very easily. I guess it's technically possible but it's not an area of work that MoI is currently focused on so it's not going to be particularly easy.

If you don't want to change the data then to start with you would not want to use the sub-d importer because that applies a sub-d smoothing process onto the polygon control cage which does modify shapes making a kind of melty smoothed down result. This works fine when the polygon mesh has been set up from the beginning to be used for sub-d smoothing but otherwise not.

- Michael

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Hi Andy,

re:
> So what I want to do now (for example) is create a NURBS surface over the top, maybe
> just part of it, and then extrude that. But how?

That's a process called "reverse engineering" and it's a pretty specialized and advanced type of use for CAD.

MoI is not designed to be a reverse engineering tool so it's not really a good fit to try doing this in MoI.

You might try Rhino, there are some reverse engineering tools made for it some info here:
https://wiki.mcneel.com/rhino/reverseengineering

- Michael

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Seems it's only triangles



try to make quadrangles before the importation! ;)

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When you created your obj to 3DM converter what was the intended usage?

I tried creating a surface in Meshlab from the simplified point cloud (surface reconstruction), saved as a new obj, run through your converter, but still no faces. So I guess your converter does not generate faces?

Andy

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I think if I could generate curves from silhouettes of the surface using the CPlane option, then I think that would get me most of the way there. Seems the silhouette feature won't work on my collection of triangles, because it's not an object?

Andy

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Hi Andy,

re:
> When you created your obj to 3DM converter what was the intended usage?

Primarily for cases with structured objects, like boxes and cylinders, stuff like that which is easier to reverse engineering than freeform surfaces.

It's not an area that MoI is primarily focused on, which is why it's a separate tool and not a built in function.


re:
> So I guess your converter does not generate faces?

Correct, the converter generates closed polyline curves, not faces. But you can turn triangles into faces using the Construct > Planar tool in MoI.

However, like I've been describing previously MoI and CAD programs in general are not designed to work on faceted triangle data.

- Michael

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