CTEVT📚 Cartography – Chapter 4: Graphic Variables (Full Chapter + Free PDF + Illustrations)
🎨 Maps speak through graphics — lines, colors, symbols, and patterns that transform raw data into visual stories.
Chapter 4 of Cartography (EG 2201 GE) in the CTEVT Diploma in Geomatics Engineering (4th Semester) introduces the powerful concept of Graphic Variables — the visual elements that make maps understandable, attractive, and scientifically accurate.
📥 Download the Free PDF Notes and learn how cartographers use shape, size, color, and texture to represent information effectively in both paper and digital maps.
📌 Overview
Graphic variables are the building blocks of map design.
They determine how features appear — whether big or small, dark or light, dotted or solid.
A well-designed map doesn’t just show data; it communicates meaning visually.
Developed from the works of Jacques Bertin (1967), graphic variables form the foundation of visual semiology in cartography.
🎥 Watch the Full Chapter 4 Video
👉 [Click Here to Watch on YouTube]
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📚 What’s Covered in Chapter 4: Graphic Variables
This chapter teaches how visual characteristics of symbols can be used to represent spatial data clearly and effectively.
✔️ Definition of Graphic Variables
A graphic (visual) variable is a visual property of a symbol that can be varied to represent information on a map.
“Graphic variables are the language of cartography — they let maps talk without words.”
They are used to distinguish, classify, and emphasize different map features such as rivers, roads, land use, and population zones.
✔️ Importance of Graphic Variables
- Enhance visual communication and map readability
- Allow differentiation between quantitative and qualitative data
- Support data hierarchy (major vs. minor roads, big vs. small towns)
- Make thematic maps more intuitive and aesthetic
- Enable universal understanding across languages
🧩 Types of Graphic Variables
Graphic variables can be grouped into planar, linear, and point symbol types depending on the feature represented.
Here are the main types of graphic variables used in cartography 👇
🎚️ 1️⃣ Size
Represents quantitative differences (how much or how many).
📍 Example:
Larger circles for big cities, smaller ones for small towns.
Thicker lines for highways, thinner lines for local roads.
🌀 2️⃣ Shape
Used to represent qualitative (categorical) differences.
📍 Example:
- Circle for cities
- Triangle for mountain peaks
- Square for administrative centers
🌗 3️⃣ Value (Lightness or Darkness)
Used to show order or magnitude through shading intensity.
📍 Example:
Darker shades for higher rainfall or population density; lighter shades for lower values.
🧭 4️⃣ Orientation
Used for showing direction or alignment of features.
📍 Example:
Hatched lines slanted in different angles to indicate slope direction or wind flow.
🧵 5️⃣ Texture (Grain or Pattern)
Represents differences in surface quality or density.
📍 Example:
Dense dots for forest areas, sparse dots for grasslands, cross-hatching for built-up zones.
🌈 6️⃣ Color (Hue)
Color hue is one of the most powerful visual variables — it conveys thematic differences and emotions.
📍 Example:
- Green for vegetation
- Blue for water
- Brown for elevation
- Red for urban areas
🔲 7️⃣ Position
Represents location — where each symbol is placed on the map.
It’s the most basic variable but essential for spatial accuracy.
📍 Example:
Correct placement of a river line or school point feature on the coordinate grid.
🧠 Application in Thematic Mapping
Graphic variables are vital when designing thematic maps, where data visualization must be both meaningful and attractive.
| Variable | Type of Data | Example Map Use |
|---|---|---|
| Size | Quantitative | Population by city |
| Shape | Qualitative | Land use category |
| Value | Ordered | Rainfall distribution |
| Orientation | Directional | Wind or slope |
| Texture | Density | Vegetation cover |
| Color | Qualitative | Soil or geology |
| Position | Locational | Settlement distribution |
🧩 Nepalese Cartography Examples
🇳🇵 Survey Department Topographic Maps
- Use blue for rivers, brown for contours, green for forest, and black for settlements.
- Employ varying line thickness for roads and boundaries.
- Apply different symbols for schools, temples, and industries.
🎓 GIS and Digital Mapping Tools
In QGIS or ArcGIS, these variables are applied via Symbology settings:
- Graduated symbols (size)
- Categorized colors (hue)
- Pattern fills (texture)
- Orientation angles (line direction)
🎨 Designing Effective Map Symbols
Good symbol design should be:
✅ Simple – easy to understand
✅ Consistent – same meaning across maps
✅ Scalable – visible at any map scale
✅ Aesthetic – visually balanced and uncluttered
🧪 Practical Exercises
1️⃣ Draw examples of each graphic variable using color pencils or software.
2️⃣ Create a thematic map showing rainfall or population using graduated colors.
3️⃣ Design your own map legend for land use types.
4️⃣ Compare a Survey Department map with a QGIS map and identify which visual variables are used.
5️⃣ Experiment with symbol size and color contrast to see which combinations communicate best.
🧩 Key Takeaways
✅ Graphic variables are visual tools used to represent spatial data on maps.
✅ They help differentiate types, magnitudes, and relationships.
✅ Effective symbolization improves both aesthetics and accuracy.
✅ Mastering visual variables is essential for all cartographers and GIS users.
📂 Download Free PDF Notes – Chapter 4: Graphic Variables
Perfect for:
✅ CTEVT exam preparation
✅ Lab assignments on symbolization
✅ QGIS and ArcGIS practice
🔽 [Download Notes – Chapter 4: Graphic Variables (PDF)]
🧮 Practice Questions for Students
🧾 Short Questions
- What are graphic variables?
- List any five types of graphic variables.
- Which graphic variable is used for quantitative data?
- Differentiate between shape and size in map symbolization.
- What is the importance of color in map design?
📚 Long/Analytical Questions
- Explain different types of graphic variables with suitable examples.
- Discuss the role of graphic variables in thematic mapping.
- How are visual variables applied in GIS symbology?
- Compare manual and digital symbolization techniques.
- Describe the importance of visual hierarchy in cartographic design.
💡 Study Tips to Master Chapter 4
🔹 Memorize all seven graphic variables with examples.
🔹 Practice by redesigning a small area map with your own symbology.
🔹 Analyze Survey Department maps for symbol consistency.
🔹 Use color theory — complementary hues make maps visually appealing.
🔹 Revise through visual flashcards (shape, size, color, value).
🎯 Lessons Learned from Chapter 4
✅ Understand the concept and purpose of graphic variables.
✅ Identify which variable suits which data type.
✅ Apply visual hierarchy in map design.
✅ Relate traditional symbolization to modern digital mapping software.
📘 Explore More from Cartography
📚 Chapter 1: Introduction – Download PDF
📚 Chapter 2: Map – Download PDF
📚 Chapter 3: Branches of Cartography – Download PDF
📚 Chapter 4: Graphic Variables – Download PDF
📚 Chapter 5: Map Projection – Download PDF
📚 Chapter 6: Map Sheet Numbering – Download PDF
📚 Chapter 7: Generalization – Download PDF
📚 Chapter 8: Relief Representation – Download PDF
📚 Chapter 9: Color – Download PDF
📚 Chapter 10: Digital Cartography – Download PDF
📚 Chapter 11: Map Reproduction – Download PDF
🎥 Watch the Full Chapter 4 Video
👉 [Click Here to Watch on YouTube]
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