Difference between revisions of "Blender Modeling Tools"
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#After Modeling press control-w to remove doubles
#After Modeling press control-w to remove doubles
#Always build a model at least twice
#Always build a model at least twice
Revision as of 14:33, 5 June 2008
The Concept of 3D Modeling
3D modeling is the process of connecting vertices with lines and surfaces to create solid objects. Unlike clay modeling or bronze modeling, digital modeling does not naturally give objects the appearance of texture instead the objects will appear to have smooth surfaces. Realism is thus achieved by creating a surface on to which a texture can be applied. The surface in 3D modeling is called a mesh.The ability to create a proper mesh for 3D modeling is achieved through practice. Creating a proper mesh is probably the only skill that really matters for a beginner. Hence learning the tools of mesh creation are of paramount importance. If a modeler does not learn the basic steps of mesh creation they will never be able to advance toward the other more complex tasks required for successful 3D animation.
The essential tools of modeling can be used to create a wide variety of objects. Indeed from mundane projects to complex projects new modelers will find that adding, grabing, rotating, scaling, extruding and adding vertices are all that is necessary to complete projects of varying difficulty. In addition these modeling concepts are transferable to all 3D modeling programs. Hence though the instructions listed below are for Blender the concepts can be transfered to other 3D programs.
It is necessary to have some sort of mesh to begin modeling from. When considering a starting point it is always necessary to think about needs to be done to the primitive object to create the complex object. In particular the modeler must keep in mind that it is always easier to remove geometry than it is to add geometry. With this in mind the modeler must choose 3D objects that have enough geometry to work off of that it will not be necessary to add new geometry later. Cubes are usually a good starting point because they have a well defined 3D profile and they can be subsurfed into other cylinders or spheres. Cubes are also useful because they have a very simple geometry this makes them easier to work with than other primitive meshes.
In Blender the modeler can add meshes by pressing the spacebar and then add mesh. This will give a list of options. Usually it is best to try to build meshes out of one primitive because this preserves clear connection between vertices. However there are times when it is necessary to combine primitive objects to achieve a desired result. In these situations the modeler can use the spacebar add function to add the second component. This second component can then be moved into place and joined with the primary object. Thinking in terms of primary and secondary objects is often a good way of conceptualizing a model because it forces the modeler to focus on creating the model using the primary object as the main reference. It is important to recognize the difference between adding a second object in edit mode and object mode. Adding a second object in edit mode adds the second object as vertices linked to the first object. This eliminates the need to join objects later on. Adding a second object in object mode adds the second object as an independent object.
Often known as translating or moving grabbing is one of the most common commands in Blender. Grabbing can be used in object mode or edit mode. Object mode grabbing is best used to position separate objects in relation to each other. Grabbing in edit mode can be used to deform object through moving vertices. Grabbing is hence one of the primary ways of deforming vertices to create more complex objects out of primitive objects. It is important to realize that grabbing individual vertices does not break the relationship between the selected vertex and the other vertices of an object. Hence when the user grabs a vertex it will deform the mesh in relation to the other vertices.
There are to ways of grabbing an object the first is using key commands. Grabbing an object or vertex using key commands consists of selecting the object by right clicking and then pressing g to grab the object. By default pressing g will be a free grab. The grab can be constrained by pressing g in combination with x,y or z. Doing this will constrain the movement to one of these axes. The other way of accomplishing a constrained grab is to select an object or vertex and then using the control node to move the selected object along one of the axes. Either of these accomplishes the same task although it is usually more precise to use the g hotkey.
Rotation allows the modeler to reorient entire objects or groups of vertices. This is useful in situations where an object was created with one orientation and needs to be reoriented to in another direction. For groups of vertices rotation allows the creation or curves or the adjustment of angled surfaces.
Rotation can be accomplished by pressing r. Doing is allows freehand rotation. Freehand rotation will always be relative to the angle of the perspective. Therefore if the user has the perspective aligned to an odd angle the rotation will tend to be skewed at a similarly odd angle. This problem can be overcome by constraining the rotation to an axis. As with grabbing constraining to an axis is accomplished by pressing x,y or z after pressing r. Pressing control while effecting a rotation will constrain that rotation to units of 5. This provides a direct way of rotating by a fixed amount. As with grabbing, rotation does not break the relationship to the other vertices of the object. Thus the modeler must watch how the rotating vertices effect the stationary vertices. Rotating vertices is an excellent way of creating inconsistent geometry in a model.
In modeling it is often necessary to make an object larger or to uniformly expand a group of vertices. Scaling is often the best way to accomplish this task. To scale an object is to take all of its vertices and increase the distance between them in a uniform fashion. To scale vertices is to do to do the same thing except it does not preserve the proportional distance between the selected and unselected vertices. Scale a group of vertices is hence similar to grabbing all of the vertices and translating them in a uniform direction relative to the center point of the object. Scaling vertices is useful for making an object larger on one side than another. One might use this to make a vase out of a cylinder.
To scale the user must press s. This scales in relation to the user's perspective. To define a direction of scaling the user can press x,y or z. Pressing control will constrain the scaling procedure to the grid. Scaling in object mode defines the object as being larger than the value of its vertices. That is it performs a uniform resizing on all of the objects vertices. In edit mode resizing scales the actual position of the vertices in relation to the control point of the object.
Extrusion is a way of expanding an object by actually adding geometry. Extrusion takes a vertex and duplicates it while preserving its connection to the parent vertex. Thus extruding a single vertex will create an edge connecting the two vertices. Extruding an edge will create a face between the old and new edges. Finally extruding a face will create faces connecting the peripheral edges of that face to its original location. Extrusion is powerful because it adds geometry. Because it is an additive process it does not cause deformation of the preexisting geometry.
Extrusion can be accomplished by selecting a vertex, edge or face and then pressing e. As with grabbing and scaling pressing x,y or z will constrain the extrusion along these axes.
creating extra vertices
Often in order to manipulate a 3D object the user will want to add extra vertices to an object so that it is easier to control. For instance it may be necessary to add a ring of vertices at the center of an object so that it can be scaled to be wider in the middle. In order to do this the modeler must create vertices at the necessary points on the mesh. When doing this an animator must consider the computational resources which must be devoted to adding vertices and then balance these with the boost of realism the model will receive. With this in mind there are two ways that a user can add vertices.
- Loop cutting adds vertices in a ring around the model. By pressing k and then left clicking a ring will appear around the object. This ring will create a vertex at every edge it intersects. Thus new vertices will be added.
- Subdivide subdividing splits the selected edge or face in half. This gives the user the ability to add geometry to an object. By selecting an edge or face then pressing control-w the surface will be subdivided.
The choice between these two options is depends entirely upon which one can accomplish the goal while creating the fewest vertices.
- Always minimize geometry while modeling
- After Modeling press control-w to remove doubles
- Always build a model at least twice
Blender Basics from Blender Underground on Viddler