Jump to content

Recommended Posts

I'm trying you loft a surface with more than 3 sides. I've extracted NURBS curves from a solid shape that is too complex to take the texture I need. How would you suggest creating a loft surface with more than 3 sides?

 

The shape I'm trying to construct is a car body, so the NURBS curves are the wheel well, the trunk of the car, door frames etc.

 This image shows the curves I'm using.

Screen Shot 2017-11-03 at 9.23.54 PM.png

Edited by tringas1

Share this post


Link to post

@tringas1- Modeling a vehicle will take some effort! Many ways to approach it, but probably all will need to reduce the car to components such as hood, quarter panels, roof, doors, and others as you mention.  Sometimes a symmetrical object easier to model as a half, then mirror the other half.  Vectorworks offers process with NURBS curves and surfaces, interpolated surfaces, and subdivided surfaces.  Investigate these.  I think the NURBS will difficult, but possible.  Interpolated surfaces seem to be limited to no holes (doors, windows, etc), but I have not much experience.  Sub D might be a better path than NURBS, but others will have to comment on that.

 

 

Anyway two different approaches with NURBS:

 

Create Surface from Curves. - It's in the Model menu>3d Power Pack. Might work for you, but not much control at edges.

Loft Surface of ribs - Initial set up is pretty easy by repeatedly duplicating a starter rib and stretching it into place with Select tool (Top Plan).

But then probably lots of adjusting vertices with Reshape tool and relofting.  NURBS don't like sharp corners, so sections are probably necessary.

 

Post back as things progress. Hopefully faster responses!

-B

SurfaceFromCurves.png

NURBS Ribs Plan.png

Ribs Lofts.png

RibLoftsAll.png

Share this post


Link to post

After having played around a bit with this, I agree that lofting NURBS curves is the way to go. 

 

VW is however probably not an ideal tool for such modeling. It can be done, but it's very difficult. Doing proper proper panel fairing requires a ot of micro adjustments, and VW has two user interface weaknesses in that respect: 1/ You can't nudge any given selection of control points with the arrow keys. 2/ You can't edit more than one patch at the time. 

 

Cars by Claes Lundstrom.jpg

Edited by Claes Lundstrom
  • Like 1

Share this post


Link to post
20 hours ago, Benson Shaw said:

@tringas1

Post back as things progress. Hopefully faster responses!

 

 

@Benson Shaw

Chose the no rail mode from loft surfaces. pretty happy with the rear quarter panels. Will post more progress later.

Screen Shot 2017-11-06 at 10.19.31 PM.png

Screen Shot 2017-11-06 at 10.19.21 PM.png

Screen Shot 2017-11-06 at 10.19.56 PM.png

Share this post


Link to post
12 hours ago, Pat Stanford said:

Claes,

 

Does TouchCAD offer the features you are saying VW is missing?

In this case, yes, but my point is that it can also be said about many other reasonable capable NURBS based modeling programs too. VW could have been so much better with just a few minor tweaks. 

Share this post


Link to post

Looking good there @tringas1. How long did it take you to get to that bottom image?

Share this post


Link to post

I did this while drinking my morning coffee. so about 30-45min. I played with adding and subtracting the number of profile curves that I have. I took the profile curves from a solid shape that I subtracted other solid shapes from till I got the look I wanted, but the problem was that I couldn't add any texture or consistent color to it by the time I was finished shaping it.

Edited by tringas1

Share this post


Link to post

@tringas1Lookin' good!

Ribs seem to work for you.

Another similar option is contours - eg more or less concentric NURBS curves similar to terrain contours, then loft among them. Careful to make all same direction.

Also -  a 3d locus can be part of a loft. eg sequence of diminishing ribs can end at a locus, which closes the shape at a point.

 

Please keep posting. We wanna see it!

 

-B

Edited by Benson Shaw

Share this post


Link to post

This is very appropriate use of NURBS modeling. Quote & link to Wikipedia article:

“. . . 

In 1946, mathematicians started studying the spline shape, and derived the piecewise polynomial formula known as the spline curve or spline function. I. J. Schoenberg gave the spline function its name after its resemblance to the mechanical spline used by draftsmen.[2]

As computers were introduced into the design process, the physical properties of such splines were investigated so that they could be modelled with mathematical precision and reproduced where needed. Pioneering work was done in France by Renault engineer Pierre Bézier, and Citroën's physicist and mathematician Paul de Casteljau. They worked nearly parallel to each other, but because Bézier published the results of his work, Bézier curves were named after him, while de Casteljau’s name is only associated with related algorithms.

. . . “

 

https://en.m.wikipedia.org/wiki/Non-uniform_rational_B-spline

 

-B

Share this post


Link to post
19 hours ago, tringas1 said:

More Progress with the no rail loft surface.

Screen Shot 2017-11-07 at 8.23.06 AM.png

Screen Shot 2017-11-07 at 8.23.23 AM.png

 

 

A much easier way to build for example a fencer is to just generate a clean basic shape, in this case the entire side panel of a car, and then trim out the opening with simple extrusions from the side. In the case a circle with a rectangle extension (add surface) for the wheel arches and a double line polygon for the door gaps. 

 

 

fender.jpg

Share this post


Link to post

@Claes Lundstrom

I've had to let those surfaces sit a brew for a while, when I come back to them later I'll be able to look at them without frustration.

Here is a detail piece of the car i'm working on i'm trying to smooth the edges out instead of having them in straight section to make up the whole curve.

Screen Shot 2017-11-11 at 12.02.55 PM.png

Screen Shot 2017-11-11 at 12.02.14 PM.png

Screen Shot 2017-11-11 at 11.58.07 AM.png

Share this post


Link to post
On 11/8/2017 at 12:29 AM, Claes Lundstrom said:

 

 

A much easier way to build for example a fencer is to just generate a clean basic shape, in this case the entire side panel of a car, and then trim out the opening with simple extrusions from the side. In the case a circle with a rectangle extension (add surface) for the wheel arches and a double line polygon for the door gaps. 

 

 

fender.jpg

Claes: Great forest / trees example, thanks.

Share this post


Link to post
14 hours ago, mjm said:

Claes: Great forest / trees example, thanks.

Could be, though a simple texture with transparency and bump map on a comparatively simple shape would probably be more efficient, as much of the work is then done by the video card. Solid modeling may generate huge files, which lags modeling and rendering speed. Should therefore be used wisely and with moderation. 

 

In the example, I converted a sphere into NURBS, chopped off the bottom a bit unevenly and the applies a simple texture I created based of a simple leaf shape, which I repeated randomly while making small variations in color and shape in VW 2D. Easy enough. Left picture as it looks on OpenGL and right  in Renderworks, where the bumps are noticable . 

 

 5a083c0a13418_Treetexture.thumb.jpg.280818b5c31563a4c23d6cd27b5d7bc2.jpg

Share this post


Link to post
19 hours ago, tringas1 said:

@Claes Lundstrom

I've had to let those surfaces sit a brew for a while, when I come back to them later I'll be able to look at them without frustration.

Here is a detail piece of the car i'm working on i'm trying to smooth the edges out instead of having them in straight section to make up the whole curve.

Screen Shot 2017-11-11 at 12.02.55 PM.png

Screen Shot 2017-11-11 at 12.02.14 PM.png

Screen Shot 2017-11-11 at 11.58.07 AM.png

 

Share this post


Link to post

Easy to do if I understand you correctly. Just three NURBS curves lofted into one surface. All basically based on the same shape, though the one in the middle being slightly bigger in all directions. 

 

 

Skärmavbild 2017-11-12 kl. 13.34.42.jpg

Share this post


Link to post

 

yes, @Claes Lundstrom I'm going for something just like that. I tried "create surface from curves" and it wouldn't read the curve network. Next, I tried the Birail sweep mode from loft surface tool but it likes to make the curve with straight lines as you see above. I'm wondering if it is my graphics card that will not produce the image I want.

Share this post


Link to post
3 hours ago, tringas1 said:

 

yes, @Claes Lundstrom I'm going for something just like that. I tried "create surface from curves" and it wouldn't read the curve network. Next, I tried the Birail sweep mode from loft surface tool but it likes to make the curve with straight lines as you see above. I'm wondering if it is my graphics card that will not produce the image I want.

Are you rendering in OpenGL? Go to View>Rendering>OpenGL options and turn up the detail level.

Alternately, when you create your sweep, make sure you're not using the "ruled" option.

Kevin

Share this post


Link to post
16 hours ago, tringas1 said:

 

yes, @Claes Lundstrom I'm going for something just like that. I tried "create surface from curves" and it wouldn't read the curve network. Next, I tried the Birail sweep mode from loft surface tool but it likes to make the curve with straight lines as you see above. I'm wondering if it is my graphics card that will not produce the image I want.

 

Easy enough. I started with a 2D arch, converted it into NURBS, Grouped in and compressed it to get that bumper shape using the scaling handles. I then copied it and made a slightly higher and wider copy and then a second copy of the original. I then moved them apart to that the smaller versions where located on each side of the bigger one. I then lofted the curves into a simple NURBS surface. You can then experiment  a bit with the shape bu undoing the lofting and modify the curves a bit until you get the shape you want. Yes it's a plain OpenGL rendering. You could try changing the OpenGL settings to get a better looking result though. The default setting is set to low for rounded shapes and never works properly. 

 

 

Skärmavbild 2017-11-13 kl. 09.56.38.png

Share this post


Link to post
On 2017-11-08 at 9:29 AM, Claes Lundstrom said:

 

 

A much easier way to build for example a fencer is to just generate a clean basic shape, in this case the entire side panel of a car, and then trim out the opening with simple extrusions from the side. In the case a circle with a rectangle extension (add surface) for the wheel arches and a double line polygon for the door gaps. 

 

 

fender.jpg

Just out of personal  interest and curiosity, I played around some more with this concept  to see if a decent car body shape could actually be extracted using this method. Here is what I did: 

 

I imported five untrimmed surfaces NURBS to start with (top left). I then cut openings for windows, doors, hood, grill, lights, added various panels to fill the openings and some details to make it look a little better in the rendering. I then exported the model to a rendering program called Keyshot (which I'm currently evaluating anyway) for rendering. All in all, I think it took me well under a days work. 

 

 

 

 

Car body by Claes Lundstrom.jpg

Share this post


Link to post
4 hours ago, mjm said:

Dang that's good. And how you evaluate Keyshot at this time?

Rendering quality is by far the best of quite a few programs I used over the years. Very good textures. All materials tested (metallic paint, chrome, rubber, leather, glass ) looks very realistic. The background image used was a stock one, it's 360, and it instantly generates shadows and reflections in the model despite the model not really standing on something, and updates instantly and follows the model when you rotate the model. Photo realistic realtime updates. I'm testing on a demo, so what you see are screen dumps from various views, and it takes say 5-10 seconds to get there after a change of say color of view. Seems to communicate well with VW in all sorts of file formats, including IGES, STEP, DWG, DXF, 3DS, OBJ, VRML, Collada, etc. 3DS and Collada allows you to bring over Renderworks stuff like textures and lights, but where Collada works better as it exports as NURBS models whereas 3DS exports as trimeshes. So far good then. Bad things, and the this is a colossal flaw, is that it can't smooth off a polygon or trimesh based model (what the ... where they thinking there not being able to do what virtual all other programs can do), and it's also quite expensive. 

Share this post


Link to post

So…not quite the moment to invest in it yet.

Appreciate the detailed summary.

Share this post


Link to post

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


 

7150 Riverwood Drive, Columbia, Maryland 21046, USA   |   Contact Us:   410-290-5114

 

© 2018 Vectorworks, Inc. All Rights Reserved. Vectorworks, Inc. is part of the Nemetschek Group.

×
×
  • Create New...