# Weird Surface

**URL:** <https://discourse.mcneel.com/t/weird-surface/26871>\
**Category:** Rhino for Mac\
**Created:** [November 19, 2015, 1:25am UTC](https://discourse.mcneel.com/t/weird-surface/26871 "2015-11-19T01:25:36Z")\
**Posts on this page:** 7\
**Page:** 1

<div class="post-metadata">

**Author:** ![bigjimslade](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/bigjimslade/32/62775_2.png) [@bigjimslade](https://discourse.mcneel.com/u/bigjimslade)\
**Post date:** [November 19, 2015, 1:25am UTC](https://discourse.mcneel.com/t/weird-surface/26871/1 "2015-11-19T01:25:37Z")

</div>

In this file

[Problem41.3dm](https://global.discourse-cdn.com/mcneel/uploads/default/original/3X/7/6/76fc5a1de25ba8a8c7ac857e3f701612ca797b5e.3dm) (349.5 KB)

the surface looks like

 ![](https://global.discourse-cdn.com/mcneel/uploads/default/original/3X/e/f/ef5f98c46fd9023e17b6a9b123b5b38dfb58f33a.png)  
in wireframe but looks like

 ![](https://global.discourse-cdn.com/mcneel/uploads/default/original/3X/9/d/9dfec4d81da2755d7054f930ff1c0104ed8620dd.png) 

when rendered.

What is happending?

---

<div class="post-metadata">

**Author:** ![davidcockey](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/davidcockey/32/732604_2.png) [@davidcockey](https://discourse.mcneel.com/u/davidcockey)\
**Post date:** [November 19, 2015, 2:48am UTC](https://discourse.mcneel.com/t/weird-surface/26871/2 "2015-11-19T02:48:00Z")

</div>

Display mesh setting are too coarse. Go to DocumentProperties menu and in Mesh change to “Smooth and slower” instead of “Jagged and faster”. (Based on Rhino for Windows).

---

<div class="post-metadata">

**Author:** ![pascal](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/pascal/32/479395_2.png) [@pascal](https://discourse.mcneel.com/u/pascal)\
**Post date:** [November 19, 2015, 4:09am UTC](https://discourse.mcneel.com/t/weird-surface/26871/3 "2015-11-19T04:09:31Z")

</div>

Hi Jim - see if RebuildEdges gets you anywhere with this object.

-Pascal

---

<div class="post-metadata">

**Author:** ![bigjimslade](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/bigjimslade/32/62775_2.png) [@bigjimslade](https://discourse.mcneel.com/u/bigjimslade)\
**Post date:** [November 19, 2015, 4:42am UTC](https://discourse.mcneel.com/t/weird-surface/26871/4 "2015-11-19T04:42:05Z")

</div>

Thanks, both worked.

---

<div class="post-metadata">

**Author:** ![DigiFabLab](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/digifablab/32/385179_2.png) [@DigiFabLab](https://discourse.mcneel.com/u/DigiFabLab)\
**Post date:** [November 19, 2015, 5:34pm UTC](https://discourse.mcneel.com/t/weird-surface/26871/5 "2015-11-19T17:34:10Z")

</div>

After changing the display resolution (`Mesh > Render Mesh Properties > Smoother & slower`) the result was as desired.

However, I then attempted to Trim the surface (`DupBorder, Trim`) to get rid of the remaining surface where the tight curve is. (below)  
 ![](https://global.discourse-cdn.com/mcneel/uploads/default/original/3X/9/d/9d9aac40c6bb59650014636ea22df3f0f47ff087.png)

The result was this (below)

 ![](https://global.discourse-cdn.com/mcneel/uploads/default/original/3X/6/d/6d581912a86a4d995ec2fefc329619f8195b59aa.png)

`RebuildEdges` then gave this result (below)

I also tried `ShrinkTrimmedSrf` with no effect, with the response being that the surface is already shrunk.

Suggestions to resolve this?

(@bigjimslade: Given the high number of U’s and V’s, I suspect you might get more desirable, and more easily modified results if you had a much lower number of each. If you like this shape, you could extract a few isocurves (`Curve > Curve from Objects > Extract Isocurves`) at several key points (such as kinks) and recreate the surface from network curves), or manually creating surfaces of desired shape that can be joined.)

~Dave

---

<div class="post-metadata">

**Author:** ![pascal](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/pascal/32/479395_2.png) [@pascal](https://discourse.mcneel.com/u/pascal)\
**Post date:** [November 19, 2015, 5:47pm UTC](https://discourse.mcneel.com/t/weird-surface/26871/6 "2015-11-19T17:47:18Z")

</div>

Hi Jim, Dave - DupBorder, Untrim, then Trim again with the border curve - that seems to clean it up here, even at the default mesh settings. I’ll see if I can find out why the current trims are a problem for the mesher.

Hmm - there seem to be multiple trim curves piled up in some places… still poking…

@bigjimslade - is this made in Rhino? If not where did it come from, and can you send me via private message, the file that was imported to Rhino? Thanks.

-Pascal

---

<div class="post-metadata">

**Author:** ![bigjimslade](https://sea3.discourse-cdn.com/mcneel/user_avatar/discourse.mcneel.com/bigjimslade/32/62775_2.png) [@bigjimslade](https://discourse.mcneel.com/u/bigjimslade)\
**Post date:** [November 19, 2015, 7:43pm UTC](https://discourse.mcneel.com/t/weird-surface/26871/7 "2015-11-19T19:43:22Z")

</div>

I made the whole thing in rhino. I imported a table of offsets from a spreadsheet, Then I faired waterlines; generated new frames; faired the frames; generated new waterlines. Repeat a half dozen iterations.

I posted the whole result to another question on how to better skin this.

Note that I do not need all the frames or waterlines. I just need to get the correct shape.

The result of patch is almost perfect, except that the stern the match is very poor, creating visible ripples.

 ![](https://global.discourse-cdn.com/mcneel/uploads/default/original/3X/1/4/140d8c11d0db8109355756dfc274ce6677f97a4d.png)