Week 2 Computer Aided design

Learning Objectives

The second week mainly evaluates different 2|3D design software, carries out simple Computer Aided design, presents the design through drawing and modeling.

1.1 Types and applications of software

Type	Software Name	Application Field
2D Design	Inkscape (Open Source)	Icon design, vector illustrations, web graphics
2D Design	GIMP	Brand identity, print design, complex layouts
3D Design	Autodesk Fusion 360 (Free for Education)	Mechanical design, CAM processing, product rendering
3D Design	FreeCAD 1.0 (Open Source)	Parametric modeling, architectural structures, engineering simulations

h2>1.2 Raster Graphics vs. Vector Graphics

Feature	Raster Graphics	Vector Graphics
Structure	Made up of a grid of individual pixels	Composed of paths, lines, curves, and shapes
Scalability	Pixelates when enlarged	Can be scaled infinitely without loss of quality
File Size	Usually larger, especially at high resolutions	Typically smaller due to mathematical definitions
Editability	Hard to edit; changes may affect the whole image	Easy to modify individual elements
Best Used For	Photographs and detailed images	Logos, icons, fonts, and technical illustrations
Resolution Dependency	Resolution-dependent	Resolution-independent
Common File Formats	JPG, PNG, GIF, BMP, TIFF	SVG, AI, EPS, PDF, DXF
Advantages	Rich in detail and color, ideal for complex imagery	Crisp and clean at any size, perfect for design work
Disadvantages	Blurs when resized, less suitable for precision work	Not ideal for photo-realistic images

2. Learning Process

Software Installation → Interface Familiarization → New Document Creation
View Operations (Pan/Zoom/Rotate) → Tool Learning(Shape/Text/Constraint/Extrude/Fillet/Chamfer)
Sketch Drawing → 3D Modeling → Rendering Output

3. Core Skills in 2D Design

1. General Tool Operations

Drawing Tools
- Shape Tools: Rectangle, ellipse, polygon
- Pen Tool: Bezier curve drawing
- Text Tool: Add editable text
Color Management
- Fill Color: Interior color of objects
- Stroke Color: Outline color and thickness

2. Practical Cases by Software

Inkscape
- Project: Create a plant
- Techniques:
  - Use `Shape tool` to optimize hand-drawn lines
  - `Text Tool` to Add text
  - `Drawing tool` to fill color
GIMP
- Project: Honor Tree
- Process:
  - I first found and imported a tree image using File → Open.
  - Then I created an apple graphic separately and scaled it using the Scale Tool.
  - I used the Free Select Tool (lasso) to select the apple and copied it to a new layer.
  - I duplicated the apple multiple times and placed them on the tree using the Move Tool.
  - Each apple was resized and positioned to make it look natural on the tree.
  - Finally, I added the text "Honor Tree" on the top using the Text Tool.

4. Core Skills in 3D Design

1. Basic Operation Workflow

Sketch Drawing: Circles, rectangles, arcs, and other basic geometric shapes
Constraint Management:
- Geometric Constraints (Parallel, perpendicular, concentric)
- Dimensional Constraints (Length, angle, radius)
Feature Editing:
- Extrude/Revolve to generate 3D bodies
- Chamfer/Fillet to optimize edges
Rendering Output:
- Apply material textures (metal, plastic, wood)
- Adjust environmental lighting and camera angles

2. Practical Cases by Software

Autodesk Fusion 360
- Project: LEGO brick modeling
- Techniques:
  - Parametric Design for quick size adjustments
  - Array tool can fast replication
  - Shell converts a solid model to a hollow structure
FreeCAD 1.0
- Project: Curved storage box design
- Techniques:
  - Create Geometric Sketch:three-point arc to draw a semi-arc
  - Dimensioning apply radius constraint to define arc length dimension
  - Constraints include equality constraint/perpendicularity constraint/coincidence constraint

5.Final Project

This section documents key applications in the final project, including 2D design and 3D modeling techniques.

5.1 The Multi-layer Tree

Search for “multi-layer tree” templates online and download a suitable one for editing.

Auto-Tracing

Go to File → Import, select your PNG image, and click OK.
Select the image.

In the top menu, go to Path → Trace Bitmap.

Recommended Trace Bitmap Settings:

Brightness Threshold:0.45 (suitable for black and white images)
Edge Detection:0.001 mm (best for outlines/cutting)
Colors:2 (for simplified paths)

Click “Apply” to generate vector paths.
Drag the original bitmap away or delete it. Keep the new vector path only.

Click the "A" icon on the left toolbar (Text Tool).
Click anywhere on the canvas and type "Honor Tree".
Change the font and size from the top menu.
Use the selection tool to move the text to the right position.

Finally, save the file as SVG or DXF for laser cutting.

Notes:

Use Path → Simplify (Ctrl+L) to reduce node complexity.
You can also manually refine the path using the Node Tool (N).

5.2 Apple Modeling

Start by selecting an apple PNG image and converting it into an SVG.

Then use Fusion 360 for modeling the apple shape:

Sketch → Insert SVG → Extrude → Fillet

Sketch → Draw a circle → Extrude

Sketch →Snap joint→ Extrude → Combine

Sketch → Add text “Tommy” → Extrude

Final Result: Complete apple model with engraved text.

Demonstration Video

Use EVCapture to record your screen.

Set the recording parameters.

Record the demonstration video.

Exploration of Other 2D Designs & 3D Models

Various Tree Shapes

Different Versions of the Honor Tree Design

Bookshelf

A simple wooden desktop bookshelf

Stool

A wooden bar stool

Plant stand

A tall stand for holding plant pots.

5. Software Comparison and Selection Recommendations

Summary: Inkscape is free and open source for icon and web graphic design; Illustrator is good at brand identity, print design, professional and efficient. Fusion 360 Easy to use, cloud service integration, complex assembly and CAM processing; FreeCAD is open source and free, parametric design is powerful, suitable for design and architectural modeling.

Dimension	Inkscape	Adobe Illustrator	Fusion 360	FreeCAD
Cost	Free Open Source	Subscription (Approximately ¥200/month)	Free for Education	Free Open Source
Advantages	Lightweight and flexible	Professional support for print materials	Cloud collaboration and CAM integration	Strong parametric design
Disadvantages	Limited advanced features	Steep learning curve	Offline functionality restricted	Interface interaction needs improvement
Recommended Scenarios	Rapid prototyping design	Brand visual system	Full mechanical engineering process	Architecture and open-source projects

6. Learning Reflections

Short-term Achievements:
- Master the basic workflows of 2D/3D design and be able to independently complete simple modeling and rendering.
- Understand the core advantages and application scenarios of different software.
Long-term Plans:
- Learn more tools and features in the software.
- Participate in practical cases of laser cutting and 3D printing in practical projects.