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Wednesday, April 22, 2009

Control point editing


Learn some techniques for editing control points in this beginner level Rhino tutorial. Commands covered include "SetPT", "Weight" and "MoveUVN".

23 comments:

david said...

your videos are excellent! keep them coming!

Brian James said...

Thanks David, I'm glad they're helpful. If you have suggestions on what types of modeling tools to cover in future tutorials please let us know.

Cheers,

Glen Keith said...

This is a great tutorial. Short and to the point, but very clear. It explains a lot that I have been struggling with as a new Rhino user. Other modeling tools that I would like more info on are how to draw cross sections over an imported picture. I'm trying to model a swim fin which needs an accurate foot pocket shape. Can you help?

Brian James said...

Hi Glen,
Can you give me some more details about what your trying to do with the swim fin? You can email me directly with any images or models...
brian(dot)james(at)mcneel.com

Eric said...

Hi Brian,

Could you explain how you adjusted the appearance of your control points? They're much larger and easier to see in your video. Any help is appreciated!

PS - the videos are extremely helpful, thanks.

Brian James said...

Hi Eric,
You can change the way the ctrl pts look through: Options>Rhino Options>Appearance>[the display mode you'd like to effect]>Objects

Then there's a field for control point size. I used 6 for the video tutorial and also had Anti-Aliasing on in the settings for the graphics card. This is what made them look round.

Anonymous said...

Thank you, Brian. As a Rhino noob, this was very helpful, and will help me with some of the ideas I have been unable to implement so far.

MyThirdEye said...

Hi, thanks for this tutorial; very helpful.

I'm trying to do something similar to what you described with "shrinktrimmedsrf" command toward the end of the video, but that command isn't quite working for me. I basically have some twisted rectangles that were surfaces, and I made them meshes so that I could make them all planar triangles, then I converted them back to nurbs. Now some of the shapes have control points where the corners would be if they were full rectangels. Rebuild doesn't work, so is there any way to get RHINO to remake these triangles with just 3 control points at the corners?

Thanks.

Brian James said...

Hi 3rd eye,
That's a good question. The shrinktrimmedsrf command will shrink the ctrl pt structure back to the smallest rectangular boundary. To get it to look like there are only three ctrl pts you'll need to move one pt on top of another using your pt Osnap. However there will still be two pts there.

If you make a three sided srf using sweep2, you can get the structure you're looking for. It also sounds like you might find the PanelingTools plugin useful.

Anonymous said...

Could you explain again how you made the control points look round? Can it be made from rhino options?

Brian James said...

Hi,
To make the control points round you'll need to do two things. First, change the control point size to 6 pixels (that's the size I use) in the display mode you're using. This is done in the options dialog. Second, to make them look round enable anti-aliasing on your graphics card... That's how the square control points get rounded.

Anonymous said...

I know there is a way to adjust the number of control points on a surface I just dont remmember not add but decide the number of control points.. do you know?? please I will apreciate the help

Brian James said...

You could use either the command 'Rebuild' or 'ChangeDegree' to add or remove control points from curves or surfaces. Rebuild will change the shape in most cases while increased degree will not.

Anonymous said...

Great video, thanks!

G said...

thanks - good, easy to understand and quick to watch :)

hazel g said...

Hi, Im having some real trouble with my command points in rhino. Im an architecture student and am trying to model my design in 3D. I managed one part fine but opened a new file to do the next ones, imported the plans from igs from vectorworks and now for some reason my control points are really messed up. I cant select them when i turn them on and they move when i pan around the view. Do you have any suggestions as to what might be the problem?

Brian James said...

Apologies on the delayed reply Hazel, If you're still having similar issues, please send the 3dm file in to Tech@McNeel.com and we'll take a look. The original file you imported would also be helpful.

Kolozsi Erik said...

I have a problem. When i try to modify the surface,to pull the control points, the surface will have edges(like poligons). what is the problem? thanks.

Brian James said...

Hi Kolozsi Erik,

This sounds like the degree of curvature for the surface is 1 in U and V. Run the command ChangeDegree and read the current degree of curvature in the command line for each direction of the surface domain. Degree 3 is often used for organic surfaces. Degree 1 is flat like a polygon. The Rebuild command can also be used to change degree.

Nuria said...

hi Brian
excelent tutorial. The problem I have is slighly different and I am not sure how to solve it. I've generate a Bezier surface by means of calculations ( its an optical surface) and I have a net of 4x4 control points. I want to represent the surface with Rhino. Can I introduce the coordinates of the control points and Rhino will generate the surface? If so, do you have a tutorial explaining such procedure? Thank you so much in advance

Brian James said...

Hi Nuria,

My first thought is to try the Patch command. This will allow you to form a surface through the pts and/or crvs. If that doesn't work for your purposes, please email the file to tech@mcneel.com and I can try to help more.

Anonymous said...

I Used the pipe tool and i can't turn on points on the polysurfaces, any way around it ?

Brian James said...

Points can't be turned on for polysurfaces in the same way as single surfaces. You can record History when using Pipe though or use a deformation command like CageEdit. There is also a SolidPtOn command but it is the equivalent of sub-object modeling with the Gumball and works best with linear edits. Check out the Rhino user forum too... http://discourse.mcneel.com/