📚 Cartography – Chapter 6: Map Sheet Numbering (Full Chapter + Free PDF + Nepal Examples)
🗺️ Have you ever noticed numbers like 2783 04D printed on topographic maps of Nepal?
They’re not random — they follow a scientific sheet numbering system that helps surveyors, GIS experts, and map users locate and reference any region precisely.
Chapter 6 of Cartography (EG 2201 GE) in the CTEVT Diploma in Geomatics Engineering – 4th Semester explains how the world’s mapping agencies — including Survey Department of Nepal — organize and index map sheets for efficient storage, reference, and mapping.
📥 Download the Free PDF Notes, learn how map sheets are divided, and practice decoding real sheet numbers used in Nepal’s topographic series.
📌 Overview
When mapping a large area like Earth, it’s impossible to represent it on a single map sheet.
Hence, the surface is divided into systematic grids or map sheets, each identified by a unique sheet number or code.
This numbering ensures global consistency, easy referencing, and data management for all cartographic and GIS applications.
🎥 Watch the Full Chapter 6 Video
👉 [Click Here to Watch on YouTube]
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📚 What’s Covered in Chapter 6: Map Sheet Numbering
You’ll explore the logic and hierarchy behind global and national map numbering systems — from world maps to local cadastral plans.
✔️ Definition of Map Sheet Numbering
Map sheet numbering is a method of assigning unique codes or numbers to individual map sheets in a map series so that any part of the Earth’s surface can be easily identified, retrieved, and referenced.
“Sheet numbering gives every map a unique address on Earth.”
✔️ Importance of Map Sheet Numbering
- Helps identify map location quickly
- Enables systematic map storage and indexing
- Ensures compatibility between maps of different scales
- Essential for fieldwork planning and GIS data management
- Maintains national and international map standardization
🌍 Global Map Numbering System
The International Map Series (IMS) divides the Earth into sheets based on latitude and longitude at the 1:1,000,000 scale.
Each sheet covers 4° of latitude × 6° of longitude.
🧮 Example:
- Latitude bands are labeled with letters (A–V) from south to north.
- Longitude zones are numbered from 1–60, each representing 6° of longitude (similar to UTM zones).
📍 So, a 1:1,000,000 map sheet might be labeled as 45P, where:
- “45” = 45th longitudinal zone
- “P” = latitude band
🗺️ Map Series Hierarchy (Scale-Based Division)
Each large-scale map is derived from dividing the smaller-scale parent sheet.
Here’s how international map series are subdivided 👇
| Map Scale | Coverage (Latitude × Longitude) | Sheet Division | Example |
|---|---|---|---|
| 1:1,000,000 | 4° × 6° | Main sheet | 2783 |
| 1:250,000 | 1° × 1.5° | 16 sheets from 1:1M | 2783 A, B, C...P |
| 1:50,000 | 30′ × 45′ | 16 sheets from 1:250K | 2783 04A–04P |
| 1:25,000 | 15′ × 22′30″ | 4 sheets from 1:50K | 2783 04D1–04D4 |
🇳🇵 Nepal’s Map Sheet Numbering System
Nepal’s Survey Department follows the International Map Series (1:1,000,000) as the base and subdivides it for all official topographic mapping scales.
🧮 Hierarchical Example
Let’s take Map Sheet 2783 04D as an example:
1️⃣ 2783 → 1:1,000,000 map sheet number
2️⃣ 04 → 1:250,000 subdivision code
3️⃣ D → 1:50,000 quadrant (A, B, C, D)
4️⃣ Optionally, D1, D2, D3, D4 → 1:25,000 sheets
So, 2783 04D3 would represent a 1:25,000 topographic map in the southeast quadrant of 2783 04D.
📍 Nepal’s Official Topographic Map Scales
| Map Scale | Sheet Coverage | Producer | Remarks |
|---|---|---|---|
| 1:25,000 | 15′ × 22′30″ | Survey Department | Detailed mapping for mountain & urban regions |
| 1:50,000 | 30′ × 45′ | Survey Department | Regional-scale mapping |
| 1:250,000 | 1° × 1.5° | Survey Department | Overview maps for planning |
| 1:1,000,000 | 4° × 6° | International Series | Global indexing base |
🧭 Relation Between Latitude, Longitude, and Sheet Number
Each sheet corresponds to a specific latitude–longitude extent:
- 1° latitude ≈ 111 km
- 1° longitude ≈ varies by latitude (~96 km in Nepal)
📍 Example:
The sheet 2783 04D might approximately cover
Latitude: 27°00′–27°30′ N
Longitude: 83°30′–84°15′ E
🧩 Advantages of Sheet Numbering
✅ Easy to locate maps during fieldwork
✅ Enables data overlay in GIS
✅ Simplifies national mapping and updates
✅ Maintains mapping hierarchy across scales
🧪 Practical Exercises
1️⃣ Identify which 1:50,000 sheet your district lies in.
2️⃣ Locate 2783 04D on Nepal’s topographic index map.
3️⃣ Convert a 1:250,000 map sheet into its 1:50,000 and 1:25,000 subdivisions.
4️⃣ Practice overlaying MUTM grid with map sheet boundaries in QGIS.
5️⃣ Review Survey Department’s online sheet index portal for reference.
🧩 Key Takeaways
✅ Map sheet numbering ensures consistent map reference and organization.
✅ International system divides Earth into 4° × 6° 1:1M sheets.
✅ Nepal’s Survey Department follows 2783-series numbering down to 1:25,000 scale.
✅ Sheet numbers (like 2783 04D3) uniquely define a specific area on Earth.
✅ Understanding numbering is crucial for GIS data handling and map cataloging.
📂 Download Free PDF Notes – Chapter 6: Map Sheet Numbering
Perfect for:
✅ CTEVT exam revision
✅ GIS & topographic mapping practice
✅ NEC license exam preparation
🔽 [Download Notes – Chapter 6: Map Sheet Numbering (PDF)]
🧮 Practice Questions for Students
🧾 Short Questions
- What is map sheet numbering?
- Why is sheet numbering important?
- What is the scale and coverage of a 1:1,000,000 map sheet?
- Decode the sheet number “2783 04D3”.
- Which organization produces official topographic maps in Nepal?
📚 Long/Analytical Questions
- Explain the map sheet numbering system used in Nepal.
- Describe the international map series hierarchy from 1:1M to 1:25K scale.
- Discuss how sheet numbering helps in GIS and survey data management.
- Write short notes on: (a) Indexing, (b) Subdivision, (c) Map Sheet Reference.
- Compare the coverage and usage of 1:25,000 and 1:50,000 scale maps.
💡 Study Tips to Master Chapter 6
🔹 Memorize scale divisions (1:1M → 1:250K → 1:50K → 1:25K).
🔹 Practice decoding real map sheet numbers.
🔹 Use Nepal’s Survey Department sheet index map for visual learning.
🔹 Draw your own mini grid to simulate sheet division.
🔹 Practice question: “Explain the meaning of map sheet number 2783 04D3.”
🎯 Lessons Learned from Chapter 6
✅ Learned structure and logic of map sheet numbering.
✅ Understood Nepal’s national mapping system.
✅ Can identify, decode, and reference any map sheet.
✅ Ready to apply numbering knowledge in GIS and fieldwork.
📘 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
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