Howt to Draw Curves in Rhino on Different Planes
Contents
- 1 Modeling with Nurbs
- one.1 Introduction
- 1.1.one Curves as basis for geometry
- one.1.2 Nurbs
- 1.ane.iii concept behind NURBS
- 1.2 Rhino Curve based modelling
- 1.iii Creating Curves
- 1.4 Editing the curves
- 1.iv.1 Rebuild curve or surface
- one.4.2 Moving the CV's
- 1.4.3 Combining curves
- 1.iv.4 Detaching curves
- ane.4.5 Edit Curves
- one.1 Introduction
Modeling with Nurbs
using curves as a basis for generating 3d geometry
Introduction
Curves as basis for geometry
In the previous workshop we worked with quite a straightforward method of generating 3D geometry. With CSG modelling we were able to use a set of primitives equally basis for our 3D geometry of the design. This method however has a few drawbacks. There is a trouble with what yous can generate with the CSG considering there is a fix set up of primitives and the options for changing the geometry are limited . This results in an design environment which has some serious constraints in what kind of shapes you tin brand. Although the formal complexity can be quite substantial with CSG the control and ease of generation of these shapes tin be lacking. If you want to blueprint a building with straight walls, floors and ceilings and maybe some unmarried curved elements so the CSG will do fine. However if y'all desire to design more circuitous shapes with doubly curved elements and so it can get a struggle or impossible. That is one of the reasons why CSG is less used in aesthetic design where form freedom is essential to the artistic design process.
If you look at industries where artful design plays a mayor role like industrial design and the car industry yous will come across that they often use a different type of geometry which supports the required class freedom. This geometry blazon is called NURBS. The mathematical description of a NURB is completely unlike from CSG. And equally we know a few elements which are influenced by the mathematical description are:
- Accuracy of the geometry ( important for manufacturing)
- The shapes information technology can generate
- The ability to adjust the shape
- The workflow of generating the shapes.
Due to its accurate mathematical description of fifty-fifty the most complex shapes it can be used in blueprint and manufacturing.
The grade liberty is quite extensive.
There are range of tools available to effectively adjust the geometry and to support formal exploration
Because the geometry is based on curves , the workflow will be completely different from the CSG workflow.
In this workshop we will await at the use and possibilities of NURBS modelling. The method nosotros will apply is called curve based modelling. The proper name already explains its concept. The 3D geometry is made with the help of curves and lines. The procedure has some similarities with traditional sketch pattern on newspaper. The lines divers on paper represent parts of the 3d blueprint. With curve based modelling we use these lines as a ground for making the 3D geometry. This strong link with sketch blueprint can be establish in the software used in the car industry and industrial pattern where with the use of tablets with pen input, designers sketch the design in the figurer and catechumen these lines into curves which can be used for generating the 3d pattern.
Nurbs
Certain properties of NURBS geometry brand the NURBS perfectly suitable for designing complex geometries like double curves surfaces. The form freedom which NURBS supports and the possibilities to adjust them requite the designer a broad range of 3 dimensional forms to explore. To exist able to make the correct conclusion a designer will demand a basic understanding of the topology of the geometry which will be used in the pattern process. NURBS geometry are widely used in computer aided design CAD, calculator aided manufacturing CAM and figurer aided engineering CAE software. It supports industry standards like IGES, STEP and ACIS. The ability to intuitively and anticipated arrange the curves and surfaces brand it an power full geometry suitable for design. The NURBS are a generalized derivative of the Bezier curve. (Pierre Bezier worked every bit engineer for Renault , development started in the 1960's to detect a method to correspond curved lines and surfaces for car blueprint).
Curve lines created in Rhinoceros are chosen CURVES, that are based on Bezier curveBezier Curves and are used equally the ground for NURBS modelling within Rhino. The mode the curves are defined makes is possible to depict straight lines and smooth curves.
concept backside NURBS
The concept of the construction of the lines was inspired on techniques used in the shipbuilding industry at the beginning of the 19th century. The wooden planks of the transport hull where curve past calculation weights at dissimilar points on the plank. The amount of bend of shape of the bend could exist adjusted by increasing the weight or the position of the weights.
The concept of deformation was digitally implemented in to the curves definition. With the effect that the curve in not only defined by the starting time and end signal of the line simply likewise past the weights betwixt the 2. These position and strength of the weights will determine the amount of curvature. The amount of weights between the start and terminate point are divers by the Degree . Degree 1 will mean that there are only the start and the terminate point. This volition generate a straight line. Degree 3 will contain next to the beginning and end points ii weights to define the bend. By moving the ii points, which are called appropriately Command Points, in the heart the curve will curve. Moving it further and the curve volition curve more than. By increasing the caste more Control Points are added. Most of the time however the curve is defined to a caste 3 curve for a curved line and a caste 1 for a straight line.
Parts of the geometries topology is comparable with the Bezier curve. The surface supports the same use of weighted vertices to define the curvature and shape of the geometry. The geometry itself can exist seen as a combination of two sets of "parallel" curves placed at a crosswise angle, with the mesh defined between the curves. Resulting issue is that the surface can back up 2 different degrees, one in each management. These curves on the surface are called ISOCURVES. The ISOCURVES will behave almost the aforementioned equally a Bezier curve. Selecting and moving a vertex on a surface will basically deform the ISOCURVES causing the surface to deform. The more than ISOCURVES on a surface, the more vertices are generated to deform the surface OR the college the caste of the curves, the more than vertices will be generated per ISOCURVES and surface as a whole.
The NURBS surface contains several different components. We have already found out that the NURBS surface contains ISOCURVES. The ISOCURVES are the sets of crosswise angled curves on the surface. They are in fact the curves where the surface is based on, simply are part of the surface itself.
Rhino Curve based modelling
With Rhino it is possible to create more than or less complicated surfaces based on curves. These curves are created directly past line elements like polylines, arcs etc., or indirectly by extracting line elements from early created surfaces.
Modeling in rhino environment starts with curves and more often than not ends with curves. This means that most everything made in Rhino surround could exist easily developed to be constructable. There are special curve editing tools available in Rhino that help designers to easily manipulate curves, particularly various kinds of splines. Using these controllable splines 1 tin can easily build NURBS objects (NURBS stands for Non Compatible Rational B-Splines: Those objects that usually called free-forms by Architects!).
The workflow of curve based modelling is quite straight forwards.
- You create a set of curves
- With the help of the curves you make surfaces
- These surfaces you can adjust by directly editing the surface or adjusting the curves the geometry was made from.
Creating Curves
I of the big advantages of using Rhinoceros is the simple interface. It is not cluttered with options yous almost of the time won't use and its layout is very efficient. Nosotros already know that at that place are several means on how to actuate a command.
- Typing in the control on the control line (for the more seasoned users)
- Use the tabs on the shelf (tin be useful however you will go flooded with icons)
- Using the pull down carte (straightforward choice because the commands are named)
- The use of the toolbox (very effective due to its simple arrangement of icons)
If yous look at the 'Bend pull down menu you volition come across an arrow behind about every command. This means there are boosted commands bachelor. They all will create, for instance, a line but all in a different way. Most of these options you lot won't use, but some can be quite useful.
If nosotros look at the Toolbox we run into only 7 icons related to generating various curves and lines. This the genius backside the layout of the Toolbox. In the lesser correct corner of the icon you will encounter an pointer. If you click on this arrow a flyout will appear with the additional commands. Near of the times it enough to only select the icon in the toolbox. Considering of its simple layout of only seven master icons information technology is very easy to apply.
There are 7 main icons in the toolbox to generate various curves. They all speak for themselves. For a straight line y'all will use the Lines command, for a curved line the Curves command etc. Always check the command line for additional options in one case y'all activate the command.
There is one control which is non ideal for authentic cartoon. This is the Curve control as it is displayed in the Toolbox. This option makes a CV curve. Every time you click the mouse a Command Vertex is added generating the curve. Even so nosotros know that the control vertex simply sits on the begin and end point of the curve. The rest in between are used to pull the curve into shape. How this works out is very difficult to predict. And then placing the intermediate CV's becomes a bit of a gamble. To tackle that problem nosotros take an Interpolated points bend. When you draw a curve with this pick the bend will get through the points yous have generated by clicking the mouse. It therefore gives much more command over the initial shape of the curve.
Y'all can besides type in the location of the adjacent point of the curve past using the control line. That helps yous to accurately define the bend. Or ane could utilise the Grid snap selection so every bespeak is identify on a grid bespeak for more accuracy. Keep in mind though this is non always necessary. When yous are sketching you lot also don't use a ruler and grid paper to make certain the lines accept a certain length. You can exercise the same thing in the estimator, just sketch the lines and afterwards they can be made more to scale.
When yous create a curve or line and you want to shut information technology , select the shut option in the command line or identify the terminal indicate on the start point.
Editing the curves
Once yous created the curves you can start editing them.
Rebuild curve or surface
If the amount of CV's are to depression or to high you tin rebuild your whole curve with the correct amount of CV's and caste. This technique is often used in " Patch Modelling " to simplify the patches.
You tin can rebuild your curve or surface by Edit > Rebuild
Select the amount of CV's and the needed caste of the curve or surface.
Moving the CV's
The most unproblematic and quite effective way of irresolute the shape of a bend is to motility its Control Vertices. Nosotros know that the curvature of a line is based on the position of the CV's. Selecting them and moving them will change the curvature. Still if y'all accept a straight corners you can apply the same CV'southward because they also appear at the beginning and terminate of the line, in this case at the corners. To actuate the option of editing the CV'southward click on the icon in the Toolbox. As long the control is agile the object can't be selected only the CV's. To deselect the selection RMB – click on the aforementioned icon.
Y'all tin add additional CV's by Edit > Control Points > Insert Command Betoken
Combining curves
Bring together: You tin can join multiple curves together , also straight lines with curves if they are continued. This is a unproblematic option where there is a hard connect( no deformation at the connecting point) between curves. You can utilise the Join icon in the toolbox.
Match: Curve > Curve Edit Tool > Friction match
this is a more than advanced method of joining curves. They volition align the curves so that the edges are blended together. There are 3 options available
- Position – a hard connect
- Tangency – curve blended together
- Curvature – complete smooth transition betwixt the curves
Connect bend: Bend > Connect Curves In this example the curves don't need to be connected, with this command they will be extended till they meet. Exist enlightened that connection is based on the extension of the first curve tangent to its cease point. Both curves extensions should be able to meet.
Detaching curves
Split a curve: The curves can also be deconstructed or parts cut out. There are two main options to practice this. You tin define a point on a curve and split it at that location in ii, or yous could use a cutting line crossing the point where you lot want to cut the curve. In both cases nosotros use the option of Edit > Split up or the split icon in the toolbox.
There appears an option in the control line which enables yous to select a point on the curve if the Split control is activated. If this option is not selected and then the cut bend tin can be selected. The curve is carve up and both parts remain.
Trim a curve: Trimming does the aforementioned splitting a bend with ane difference it will delete the cutting off part. Be aware that the selection of the curves is in the reverse order of the Carve up control. Check the command line!
Edit Curves
And there are some boosted editing options bachelor which speak for themselves.
Curve > Extend Bend: unlike options of extending a curve. This allows the extension of the bend tangent to the end of the bend or with the same curvature of the finish of the curve.
Curve > Fillet Curves: makes a fillet between two curves (rounding of the edge) This option is widely used in engineering. Sharp corners are from a structural point of view not platonic and then frequently these corners are rounded off. This option works with two separate curves.
Curve > Fillet Corner: makes a fillet in a corner of a single bend. This option is similar with the Fillet Curves tool. However the input in this case is a unmarried curve.
Curve > Chamfer Curves: makes a 45 degree angled line betwixt two connecting curves.
Curve > Offset Curve: makes an commencement perpendicular to a curve
Source: http://wiki.bk.tudelft.nl/toi-pedia/Rhino_Curve_Based_Modeling
0 Response to "Howt to Draw Curves in Rhino on Different Planes"
Post a Comment