Full Version: How to create front and back faces on this object.

Hello, I am brand new to this software and any type of CAD so please be patient. I have imported a mesh from Zbrush, I then drew over the object to get the basic 2d shape I want to make 3d. The issue I'm having is that when I've extruded the sides I cannot get the front and back faces to fill in. Can anyone help me with what the next stage would be or if I've done something stupid and need to try a different way of doing it? Thanks.

Attachments:
EXPORTFORFORUM.3dm

Image Attachments:
Screenshot 2024-06-24 212201.png 

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Hi Dex, so what's happening there is that Extrude only knows how to fill in the end caps if hey are planar curves.

Usually it's better to make a planar curve for the extrusion which will result in a solid, and then have some cutting curves in the side view to slice up the solid.

So more like this example:










- Michael

Image Attachments:
Extrude1.jpg  extrude2.jpg  Extrude3.jpg  Extrude4.jpg  extrude6.jpg 

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HI Dex

这是一个边界曲面问题，在moi中没有相应的处理工具，在犀牛中你应该使用嵌面（patch）工具，然后修剪。请看图片、gif的过程演示。
（This is a boundary surface problem, and there is no corresponding processing tool in Moi. In Rhino, you should use the patch tool and then trim it. Please take a look at the pictures and demonstrate the process of gif.）

首先需要在画边缘曲线时就保证它们是完整连接的（我在moi中提取并连接了边缘。）这一点是整个过程中最重要的（The most important aspect of the entire process is to ensure that the edge curves are fully connected when drawing them (I extracted and connected the edges in Moi)）


然后使用嵌面，放样，曲线拉回曲面（gif忘了演示）修剪命令，最后join缝合在一起。实际上像这种两个曲面只是厚度的变化，不使用放样而对一张边界曲面使用偏移→厚度工具的效果更好（Then use the trimming commands of inlay, lofting, and curve pulling back to the surface (GIF forgot to demonstrate), and finally join them together. In fact, two surfaces like this are only changes in thickness, and using the offset → thickness tool on a boundary surface without using a loft would have a better effect）


当然:Michael说的也没错，作为新手，应该先学会保证绘制平面轮廓线的完整性，这需要使用修剪、join、倒角等命令，还有控制点，并熟悉它们。使用曲线本身曲度对实体切割，形成曲面。然后再学会使用放样、扫略等制作边缘形状简单更大的符合光顺度的曲面，进行边界修剪。而不是是一开始就追求空间曲线形状复杂的情况形成型边界曲面 。这时常这对软件本身难以准确计算。在达到造型要求的前提下，应尽量避免这样的情况。
（Of course: Michael is also right. As a beginner, you should first learn to ensure the integrity of drawing planar contour lines, which requires using commands such as trimming, joining, chamfering, as well as control points and familiarizing yourself with them. Use the curvature of the curve itself to cut a solid and form a surface. Then learn to use lofting, sweeping, and other techniques to create surfaces with simpler and larger edge shapes that conform to smoothness, and perform boundary trimming. Instead of pursuing complex spatial curve shapes to form boundary surfaces from the beginning. At this point, it is often difficult for the software itself to accurately calculate. On the premise of meeting the design requirements, such situations should be avoided as much as possible.）

break a leg

Attachments:
EXPORTFORFORUM finsh.3dm

Image Attachments:
1.png  zz.gif 

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Hi Dex, for your case it looks like you want something like this:

2D profile:



Extruded:



The extrusion will contribute the "side walls" to the end result.

Then for the front and back surfaces, you want to construct a simplified surface that extends out across the entire shape, here done with some profiles:



Then Loft with "Loft style = Straight":



Use boolean difference to cut the extruded shape up:



Discard these excess outer pieces:



Now you will have a solid result that combines the side walls from the extrusion and the front/back shaping from the cutting objects:



So the kind of key element is to not try to "fill in" surfaces to an irregular boundary. For the NURBS modeling technique you want to have simple relaxed surfaces that extend all the way across a shape and then use booleans to impose a more complex boundary on them rather than trying to construct a surface directly to a complex boundary.

Also see here for some tips for people coming from a poly modeling background:
https://moi3d.com/forum/index.php?webtag=MOI&msg=4865.2

- Michael

Image Attachments:
dex_front_back_srfs1.jpg  dex_front_back_srfs2.jpg  dex_front_back_srfs3.jpg  dex_front_back_srfs4.jpg  dex_front_back_srfs5.jpg  dex_front_back_srfs6.jpg  dex_front_back_srfs7.jpg 

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Hi SUIYAN,

re:
>（This is a boundary surface problem, and there is no corresponding processing tool in Moi.
> In Rhino, you should use the patch tool and then trim it. Please take a look at the pictures
> and demonstrate the process of gif.）

That's something that can be useful in certain cases but it's usually a better modeling technique in NURBS to form extended simplified 4 sided surfaces and then form the final boundary by a boolean operation.

- Michael

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Appreciate the quick response guys! I will try these methods out. Couldn't be more grateful, you've been a great help. Thanks!

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HI Michael

非常认同，我在#3的讨论中也表达了这样的意思。不过人们更倾向于基于模型原本元素的直接工具，所以我的演示更倾向于此。（I completely agree, and I also expressed this idea in the discussion of # 3. However, people tend to use direct tools based on the existing elements of the model, so my presentation is more inclined towards this.）

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