Sketch Maps (Leaving Cert Geography): Revision Notes
Sketch Maps
Creating a sketch map from an aerial photograph is a fundamental geographical skill that allows you to simplify complex photographic information into a clear, manageable diagram. This technique helps you identify key features and understand spatial relationships in the landscape.
Understanding sketch maps
A sketch map is a simplified drawing that shows the main features visible in an aerial photograph. Unlike a detailed map, it focuses on the most important elements and presents them in a clear, easy-to-understand format.
Sketch map: A simplified diagram drawn from an aerial photograph that shows only the key features and their spatial relationships, usually drawn to a reduced scale.
Step-by-step process for creating sketch maps
1. Measuring and scaling
The first crucial step involves determining the correct proportions for your sketch:
- Measure both the length and width of the original aerial photograph using a ruler
- Most exam questions will ask you to draw at half-scale, meaning you reduce all dimensions by half
- Calculate your sketch dimensions by dividing the original measurements by 2
- This scaling ensures your sketch remains proportional to the original photograph
Worked Example: Calculating Half-Scale Dimensions
Step 1: Measure the original photograph
- Length: 20cm
- Width: 15cm
Step 2: Calculate half-scale dimensions
- New length: 20cm ÷ 2 = 10cm
- New width: 15cm ÷ 2 = 7.5cm
Step 3: Draw your frame using these new measurements
2. Drawing the frame
Once you've calculated the correct dimensions:
- Draw the outline frame of your sketch map using the half-scale measurements
- Ensure the frame has exactly the same shape and orientation as the original photograph
- The frame acts as your boundary and helps maintain accurate proportions
3. Creating a grid system
To help with accurate placement of features:
- Divide both your sketch frame and the original aerial photograph into nine equal squares (3×3 grid)
- This grid system acts as a reference guide, making it much easier to position features correctly
- Each square in your sketch corresponds to the equivalent square in the original photograph
The 3×3 grid system is one of the most effective techniques for ensuring accuracy. It breaks down the complex task of positioning features into manageable sections, significantly improving the spatial accuracy of your final sketch.
4. Adding directional information
Navigation reference is essential:
- Only include a north arrow if one is clearly visible on the original aerial photograph
- Never assume or guess the direction - only add what you can see
- Place the north arrow in the same relative position as shown in the original
Common Mistake to Avoid: Never add a north arrow unless you can clearly see one on the original aerial photograph. Adding directional information that isn't visible in the source material will result in lost marks.
5. Including geographical boundaries
If applicable to your location:
- Draw the coastline if it's visible in the aerial photograph
- Ensure the coastline follows the same shape and position as shown in the original
- This provides important geographical context for your sketch
6. Drawing and labelling features
This is where your sketch comes to life:
- Draw each feature requested in the exam question carefully
- Focus on showing the outline shape of features rather than intricate details
- Create a legend or key at the bottom of your sketch to explain what each symbol represents
- Label features clearly or use your key to identify them
7. Roads and rivers
These linear features require special attention:
- Always label roads and rivers on your sketch map as they're key reference points
- Remember to draw them to half-scale like everything else
- Be careful not to make roads and rivers too thick or prominent - they should be proportional to their actual size
- Many students make the mistake of drawing these features too large, which distorts the overall appearance
Critical Error to Avoid: Drawing roads and rivers too thick is one of the most common mistakes in sketch mapping. These features should maintain their proportional relationship to other elements in your sketch.
Key considerations for success
Scale consistency
Maintaining consistent scaling throughout your sketch is crucial. Every element - from buildings to roads to natural features - must be reduced by the same proportion. This creates a balanced and accurate representation.
Scale consistency is what separates a good sketch map from an excellent one. When every feature is properly proportioned, your sketch becomes a reliable geographical tool that accurately represents the spatial relationships in the original photograph.
Feature selection
Focus on the features specifically mentioned in the exam question. While you might see many interesting details in the aerial photograph, your sketch should only include what's been requested plus essential reference points like major roads or rivers.
Clarity over detail
Remember that a sketch map prioritises clarity over intricate detail. Your goal is to create a clear, easily understood diagram that shows spatial relationships and key features. Avoid getting caught up in minor details that might clutter your sketch.
Think of your sketch map as a simplified communication tool. Its purpose is to convey essential geographical information quickly and clearly, not to replicate every detail visible in the original photograph.
Key Points to Remember:
- Always measure the original photograph first and divide dimensions by 2 for half-scale sketches
- Use a 3×3 grid system on both the original and your sketch to ensure accurate feature placement
- Only add a north arrow if one is visible on the original aerial photograph
- Draw feature outlines clearly and create a legend to explain your symbols
- Keep roads and rivers proportional - don't make them too large compared to other features