📚 GIS Basics – Chapter 4: GIS Operations and Map Composition
(CTEVT Diploma in Geomatics Engineering – 3rd Semester Notes + Free PDF + Video)
GIS becomes powerful not just by storing data — but through the operations that analyze, combine, query, and extract useful geographic information.
Chapter 4 of GIS Basics (3rd Semester) explains the different GIS operations used for spatial analysis, and teaches how to design a proper map layout for presentation and printing.
📥 Download Full Chapter 4 Notes (Free PDF)
🎥 Watch the Full Chapter 4 Lecture on YouTube
🎥 Watch the Full Chapter 4 Video
👉 [Click Here to Watch on YouTube]
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📌 Overview
This chapter introduces two major parts:
1️⃣ GIS Operations (Spatial & Attribute)
The tools and processes used to manipulate and analyze geographic data.
2️⃣ Map Composition
The process of designing a complete, readable, and aesthetic map layout.
These topics form the core of GIS practical work in software like QGIS and ArcGIS.
🛰️ 1️⃣ GIS Operations
GIS operations are categorized into:
- Spatial Data Operations
- Attribute Data Operations
- Raster Data Operations
- Vector Data Operations
- Query, Measurement & Overlay
- Buffer and Proximity analysis
These operations help derive new information from existing layers.
🗂️ 2️⃣ Spatial Data Operations
✔ A. Spatial Query
Selecting features based on location.
Examples:
- Select buildings inside a municipality
- Find schools within 500m of a highway
- Identify rivers crossing a road network
Tools Used:
- Select by Location
- Spatial Join
✔ B. Attribute Query
Selecting features based on attribute table values.
Examples:
- Select roads where “type = highway”
- Find population > 10,000
- Select land use = forest
Tools Used:
- Select by Expression
- SQL queries
✔ C. Buffer Operation
Creates a zone around features.
Used For:
- School service areas
- River flood zones (100m buffer)
- Road influence zones
- Environmental protection zones
Output:
Polygon layer of the buffered area.
✔ D. Overlay Operations
Overlay combines multiple layers to create a new dataset.
Important overlay tools:
1️⃣ Union
Combines ALL features of both layers.
2️⃣ Intersect
Keeps only the overlapping area.
3️⃣ Clip
Cuts a layer using the boundary of another.
Example: Clip road network using municipality boundary.
4️⃣ Erase
Removes selected areas from a layer.
✔ E. Proximity Analysis
Used to measure distance or find nearest features.
Examples:
- Nearest hospital
- Distance from river
- Nearest road intersection
Tools:
- Near tool
- Distance matrix
- Proximity raster
✔ F. Measurement Operations
GIS can measure:
- Distance (between two points)
- Area (polygon size)
- Perimeter
- Length of roads
- Elevation difference (DEM based)
🗺️ 3️⃣ Raster Data Operations
✔ A. Local Operations
Cell-by-cell calculations.
Example:
- Add two DEM rasters
- Land suitability calculation
✔ B. Neighborhood Operations
Uses surrounding cells (within a window).
Example:
- Slope
- Aspect
- Focal mean
- Filters
✔ C. Zonal Operations
Applies calculations within zones.
Example:
- Mean elevation per district
- Total rainfall in watershed
🧮 4️⃣ Vector Data Operations
✔ Dissolve
Merge features with common attributes.
Example: Merge VDCs into districts.
✔ Merge
Combine multiple layers into one.
✔ Split
Divide a feature based on selected boundaries.
✔ Append
Add new features to an existing layer.
🎨 5️⃣ Map Composition
Map Composition is the process of creating final map layouts for printing or presentation.
A good map must be:
✔ Readable
✔ Well organized
✔ Aesthetic
✔ Accurate
🗺️ Essential Elements of a Map Layout
1️⃣ Title
Explains the theme
(e.g., “Land Use Map of Pokhara Metropolitan City”)
2️⃣ Legend
Explains symbols, colors, categories.
3️⃣ North Arrow
Shows map orientation.
4️⃣ Scale Bar
Provides distance measure in km or meters.
5️⃣ Neatline
Border that frames the map.
6️⃣ Coordinate Grid / Graticule
Shows coordinates for reference.
7️⃣ Labels
Names of roads, rivers, places, districts.
8️⃣ Inset Map
Shows location within a larger area
(e.g., Nepal map as reference).
9️⃣ Metadata / Notes
Includes:
- Data source
- Projection used
- Author name
- Date of creation
1️⃣0️⃣ Legend Arrangement & Color Scheme
Must be consistent and visually clear.
🛠️ 6️⃣ Steps of Map Composition in GIS Software
Step 1: Prepare data layers
Clean geometry, set symbology.
Step 2: Open Print Layout
(QGIS: Project → New Print Layout)
Step 3: Insert map frame
Step 4: Add map elements
- Legend
- Title
- Scale bar
- North arrow
Step 5: Adjust layout
Margins, spacing, color balance.
Step 6: Export
PDF, PNG, JPEG, SVG.
🇳🇵 Nepalese Examples of GIS Operations
✔ Risk Mapping (Disaster Management)
- Buffer around rivers
- Flood-zone overlays
- Slope calculation from DEM
✔ Municipality GIS
- Road network analysis
- Building footprint mapping
- Land use zoning
✔ Survey Department
- Map sheets composition
- Topographic map layout
- National grid systems
📂 Download Free PDF Notes – Chapter 4: GIS Operations & Map Composition
🔽 [Download Notes – Chapter 4 (PDF)]
(Includes diagrams for buffer, overlay, map layout elements, raster tools, QGIS screenshots)
🎥 Watch the Full Chapter 4 Video
👉 [Click Here to Watch on YouTube]
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🧪 Practical Exercises (As Per Syllabus)
1️⃣ Perform attribute and spatial queries
2️⃣ Create buffer for roads and rivers
3️⃣ Apply overlay tools (clip, intersect, union)
4️⃣ Calculate area, length, and distance
5️⃣ Perform raster slope & aspect analysis
6️⃣ Design a complete map layout in QGIS
7️⃣ Export map as PDF
8️⃣ Add north arrow, legend, and scale bar
🧠 Key Takeaways
✔ GIS operations provide analytical power
✔ Queries help extract specific information
✔ Buffer and overlay are core spatial tools
✔ Raster operations derive slope, aspect, etc.
✔ Map composition is essential for presentation
✔ Good maps require clarity, accuracy & structure
📝 Short Questions
- What is a spatial query?
- Define buffer.
- List any two overlay operations.
- What is map composition?
- Name four essential map elements.
- Define dissolve in vector operations.
- What is slope analysis?
📚 Long / Analytical Questions
- Explain different GIS operations with examples.
- Describe overlay operations in detail.
- Discuss the steps of map composition.
- Compare spatial and attribute queries.
- Explain raster operations: local, neighborhood, zonal.
- Describe essential elements of a good map layout.
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