Photo Realistic Rendering

AMERICAN CHOPPER

Objective:

To model the individual parts of the American Chopper and assemble and render the assembled model to the get realistic view

Types Of Commands:

• Sketch
• Feature
• Surface
• Assembly

Sketch: These commands used to create the 2D or 3D sketches and concerned dimension and the geometrical relations to define the sketch.

Features: These are used to generate the 3D parts the options such as revolve, extrudes and swept body and loft. The generated 3D parts are modelled with options such as fillet, chamfer and extrude cut, revolve cut and sweep cut.

Surfaces: Surfaces are formed by applying various surface features like extrude surface, revolve surface, loft surface, sweep surface, extend surface and ruled surface etc. Again, the generated surfaces are edited with the options trim surface and thicken surface.

Assembly: Select the components are assembled by applying the mate options such as coincident, concentric, distance, parallel etc.

1. Sketch Commands:

Creating a model begins with a sketch. Based on the sketch, we can create features. Sketch should be completely defined by applying the geometric relations and dimensions. In 3D sketch, we can snap to directions X, Y, and Z, and constraints are applied along X, Y, Z respectively. When sketching on a plane, we can snap to the horizontal or vertical directions in the plane, and constraints are applied to the Horizontal and the Vertical.

• Smart Dimension - Creates a geometrical dimension for any selected sketch entity.
• Point – It is a 1D element, it inserts a point or vertex into a sketch entity. This cannot be deleted if it is part of sketch endpoint or centre point.
• Line – Generates the lines which can be drawn horizontally, vertically or at any angle.
• Circle – Generates the circular drawing on the graphics area. There are two circle tools which are “Centre circle” and “Perimeter circle”.
• Rectangle – Generates rectangles or square with a centre point at a selected angle there are rectangles like cantered rectangle, corner rectangle. Parallelogram sketches a standard parallelogram.
• Spline – splines can be created with number of midpoints depending upon the complexity of the curve. A 2or 3 dimensional curves defined by a set of control points. Points within a spline can be added or deleted.
• Sketch Fillet - A tangent arc in between two sketch entities can be created with a radius.
• Text - It can be used to write the text necessary wherever required either it’s a plane or face of a model.
• Convert Entities - Copy a sketch entity on plane, it must have an original sketch entity already drawn and selected to use this tool.
• Offset Entities – Creates a sketch entity to a specified distance from the original entity. Must have an original sketch entity already drawn and selected to use this tool.
• Sketch Picture - Insert an image file into the background of a sketch. This allows the user to 2D sketches based on the image. Use the sketch picture property manager to alter the inserted image.
• Figure 1: 2D Sketch generated in solid works

The sketch is shown in black colour which indicates that it is completely defined. The geometric relations like coincident, parallel, equal, vertical and horizontal are shown in the green colour icons as shown in the figure 1.

2. Feature commands:

Some sketch-based features are shapes such as extrude, extrude-cut and holes. Other sketch-based features such as lofts and sweeps use a profile along a path. Applied features include fillets, chamfers, or shells they are applied to existing geometry using dimensions and other characteristics to create the feature. Then we add applied features. It is possible to create a part without sketch-based features.

• Extruded Boss/Base - An Extruded Boss/Base feature will allow us extrudes the sketches to generate prismatic solids.
• Extruded Cut – It is a tool to remove material by projecting a sketched section normal to the sketch plane.
• Split - Lines are used to divide model faces into two. Split lines are created like any other sketched feature. They can be one or more connected sketch entities. They must be oriented so that they will pass through model faces when projected normal to the sketch plane.
• Dome – It can be of two types elliptical and spherical. It can add one or more domes to the selected planar or non-planar faces. The software calculates the distance using the radius of the arc as a basis for the dome.
• Fillet and chamfer- used to modify the edges into fillets and chamfer with required dimensions.
• Plane- It is used to generate the planes at different orientation in which the required sketch is to be drawn.
• Project Curve - Select Bi-directional to create a projection that extends on both sides of the sketch. The curve can be used as a path for a sweep.
• There are two types of projected curves. Sketch on Sketch which uses two sketches to make a single curve and Sketch on surface uses a sketch to project on a surface.
• 

Figure 2: Extruded part

Figure 3: Fillet applied at the edges of the extruded part

The previous sketch in figure-1 is extruded by using the boss extrude command as shown in the figure-2. Similarly, the extrude cut command is used to remove the solid parts from the generated solid just like the extruding 2D sketch.

3. Surface Modelling:

Zero thickness geometry is known as surface. Surface modelling is a method of creating planar or non-planar complex geometry which has zero or negligible thickness. The surfaces are generally used to create models of complex shapes. The conversion of surface models into solid models and solid model into surface is also possible by using the tools available for surface modelling. The surface commands are:

• Lofted Surfaces – Creates a lofted surface between two or more profiles or sketches. Specify start and end constraints and add guide curves to specify the path shape.
• Boundary Surfaces – The boundary surface feature allows to create surfaces that can be tangent or curvature continuous in both directions.
• Extruded Surfaces – Extrudes a sketch or selected sketch contours in one or two directions two create a surface feature
• Revolved Surfaces – Revolves a sketch or selected sketch contours around an axis to create a revolved surface feature.
• Swept Surfaces – It Sweeps a closed profile along an open or closed path to create a surface feature. It uses a tangent plane at the end of the path so that the path is normal to the swept surface.
• Filled Surfaces – Patches a surface within a boundary defined by edges, sketches, or curves.
• Ruled Surfaces – Inserts ruled surfaces in a specified direction from edges. Tangent to surface, Normal to surface, tapered to vector, perpendicular to vector or sweep can be selected.
• Trim Surface – It trims the surfaces where a surface intersects with another surface, a plane or a sketch.
• Knit Surface – It combines two or more adjacent, non-intersecting surfaces into a single surface body. The surfaces must join at an edge. If the resulting knit surface encloses a volume, we can create a solid body from the Property Manager.
• Move/copy surfaces – Moves or copy surfaces about a plane or a sketch.
• Offset Surface – Offsets surfaces using one or more continuous faces. This tool helps us to create an offset surface with gaps.
• Extend Surface – Extends one or more edges or faces on a surface, based on end conditions and extension type.
• Mirror surfaces – A mirror feature is a copy of a selected feature, mirrored about a plane or planar face. A mirror sketch entity is a copy of a selected sketch entity that is mirrored about a centreline. If the original feature or sketch is modified, the mirrored copy is updated to reflect the change.

Figure 4: Two Different curves on different planes

In the figure 4, the two curves are shown in the two mutually perpendicular planes which are drawn to generate a surface by using the swept surface option. After applying the swept surface command on the two curves, the required surface is generated along the path curve by translating the sketch curve.

Figure 5: Generated Surface

These surfaces are trimmed to remove the unwanted surface and are knitted to merge into single surface. While knitting the create solid option is available to convert the closed surfaces into solids.

4. Assembly commands:

• Concentric- makes the selected surface and the curvy edges concentric
• Coincident- surfaces, edges and corners are coincides by using this command
• Distance- distance is given as constraint between the assembled parts
• Parallel- required edges and surfaces are aligned parallel to each other
• Perpendicular-edges and surfaces are aligned perpendicular to each other
• Tangent- desired edges and surfaces are assembled with the curvy surfaces with tangent relation.
• Lock- constraint the parts completely at their current position and orientation without any other geometric relation with the other parts.

Methodology:

Modelling:

All the required parts of the American chopper are to be modelled which are:

• Transmission belt:

The modelling of the transmission belt includes a defined sketch in mid plane and its extrusion. Required fillets are given to the model by using the fillet command.

Figure 6: Transmission Belt

• Kick-stand:

The kick stand is modelled with two main sketches in two defined planes for the model. The part model is generated between the two sketches of different ellipses by using the loft command. Dome commend is applied to the both end face for the curvy surface. Extrude cut the split commands are used to remove the material from the part.

Figure 7: Kickstand

• Front fender:

The modelling of the front fender includes the sketch of the cross-section of the front fender. The sketch is generated into solid by the command revolve-boss command. The portion of the generated solid is removed by using the split option and required fillets given.

Figure 8: Front-fender

• Oil tank:

The oil tank is modelled by using the combine command with the two solids generated with two different sketches in two different mutually perpendicular planes. After generating the solid, fillet with the required dimensions are given and shell command applied to the solid with certain thickness. The appearance of the model is edited with sienna colour and fillets with the grey colour.

Figure 9: Oil-tank

• Chain:

The chain is modelled mainly with the command curve drawn pattern. So, the curve of the chain though the chain is aligned is drawn for using the pattern command. The two end plates of the chain are generated and saved as the blocks to use in this modelling. As the two end plates and pins of the chain repeats in certain order, the end plates and the pins arranged in the same order in the starting of the curve for iterating the same order in the curve drawn pattern. The pattern command is applied to the arranged order of pins and endplates to get the chain model.

Figure 10: Chain

• Pedal:

The modelling of the pedal includes splines in the main sketch which gives the curvy structure to the body. All solids are generated by the extrude command and linear pattern is used to generate the similar solids and similar fillets.

Figure 11: Pedal

• Front-Wheel and Rear-Wheel:

These modelling consists of the revolve command to generate the tire. The rim of the tires is generated by the circular pattern of an extruded solid from the sketch of the splines with the concerned dimensions. Callipers, rotor and sprocket are generated by the extruded command and some portion of the solids is removed by the extrude cut command. The concerned appearances are given to the models.

Figure 12: Front-wheel

Figure 13: Rear wheel

• Front Fork:

Some solids of this part are generated by the extrude command and some other solids are generated by the sweep extrude command. Whereas the head lights are generated by the revolve command and again shell command is given to the headlights with certain thickness. The concerned appearances are given to the model.

Figure 14: Front-fork

• Chassis:

Boss-extrude and sweep extrude command are used to generate the solids in this model. Fillets and the required appearances are also given.

Figure 15: Chassis

• Engine:

In this modelling, composite curve option is used to generate the centre curve of the exhaust pipes of the two engines. The exhaust pipes are generated by using the sweep extrude command. The fins of the engine are generated by using the linear pattern command. Remaining solids are generated by the extrude command and required fillets are given at the corners.

Fig16: Engine

• Gas tank:

The gas tank model is generated mainly with the surface commands like surface loft, surface sweep. The unwanted portion of the surface is trimmed by using the surface trim. As the surface of this models has complex curves, the blueprint of the bike model is used to generate the spline near to the actual curves. Every surface knitted and given with the create solid option to generate the solid of the modal. The required fillets and appearances of the model are given.

Figure 17: Gas tank

Assembly:

In assemble, the main part i.e., chassis is imported first and is fixed at its own position and remaining parts like kick-stand, engine, front fork, front and rear wheel, front and rear fender are assembled with the chassis. After assembling every part, the status of the assemble i.e., undefined, defined and over defined is checked and ensure that it should be defined only. The presence of solid of one part into another part is also avoided. As the kick stand and the front fork should be given with the angular degree of freedom about its pivot point, the advanced mate option is used for giving the degree of freedom within certain limits. The advanced mate option can define the assemble and also provides the motion to the part. The portion of the chain is observed in the region of the chassis so, the chassis is modified according to the chain after the assemble.

Figure 18: Chopper Assembly

Rendering:

Rendering is done to get the realistic and attractive view of the model. It is done by using different types of lights and the light directions and orientations. Some background images are also used to make the view more vibrant and attractive.

Figure 19(a): Rendered bike

Figure 19(b): Rendered bike

Figure 19(c): Rendered Bike

Figure 19(d): Rendered Bike

Figure 19(e): Rendered Bike

Conclusion:

The parts of the chopper bike are modelled with defined sketches and the modelled parts are assembled. The assembled model is rendered to get a realistic view.