GIS Fundamentals Cheat Sheet

Geographic Information System (GIS) is a powerful tool for capturing, managing, analyzing, and visualizing spatial data. It integrates database technology with digital mapping to answer complex geographic questions and support decision-making across various real-world applications.

Core Principles

GIS combines spatial and attribute data for comprehensive analysis.
Vector and Raster are the two primary data models for representing geographic information.
Map projections are essential for transforming the Earth's 3D surface onto a 2D plane.
Coordinate systems (GCS, UTM) define precise locations on Earth.
Data quality (accuracy, completeness, lineage) is crucial for reliable GIS analysis.
Visualization techniques transform data into understandable maps and graphics.

Action Steps

Define the problem and identify relevant spatial data.
Select appropriate data capture and preparation techniques.
Choose suitable data models (Vector/Raster) and coordinate systems.
Perform analysis using GIS operations (overlay, network analysis, etc.).
Visualize results effectively using appropriate cartographic techniques.
Interpret findings and communicate insights to the target audience.

Formulas

Distance = Speed of Light x Travel Time
RMS = \sqrt{\frac{\sum(actual - predicted)^2}{number \ of \ points}}

Key Terms

GIS: Geographic Information System: A computer-based system for capturing, storing, managing, analyzing, and presenting spatial data.
Vector Data: Represents discrete geographic features using points, lines, and polygons.
Raster Data: Represents continuous fields or surfaces using a grid of cells (pixels).
Map Projection: A mathematical transformation to represent the Earth's curved surface on a flat map.
Coordinate System: A system (e.g., GCS, UTM) that defines locations on Earth using coordinates (latitude, longitude, or projected x,y).
Topology: Rules defining spatial relationships (adjacency, connectivity, containment) between features.
Vector Overlay: Combines multiple thematic vector layers to create a new layer with combined attributes.
Raster Overlay: Performs cell-by-cell calculations on multiple raster layers using map algebra.
Spatial Indexing: Techniques (e.g., R-trees, Quad-trees) to speed up spatial data retrieval in databases.
Visual Variables: Cartographic elements (size, value, texture, color, orientation, shape) used to encode information on maps.

Pro Tips

Always consider the temporal dimension for dynamic data.
Understand the limitations of map projections to avoid distortion.
Use appropriate spatial indexing for efficient database queries.
Validate data quality rigorously before analysis.
Choose visual variables that best represent the data and suit the audience.

Pitfalls to Avoid

Ignoring data accuracy and precision can lead to flawed conclusions.
Using the wrong map projection can distort spatial relationships.
Over-reliance on automated classification without understanding the data.
Poor map design can obscure key information.
Failing to consider the target audience when designing maps.

Real World Examples

Urban Planning: Using GIS to plan roads and sewage lines, minimizing environmental impact.
Navigation: Google Maps uses GIS for real-time traffic routing and GPS for location services.
Environmental Monitoring: Tracking forest fires or predicting storm impacts using spatiotemporal models.
Tax Management: Municipalities use GIS to track land parcels, ownership, and boundaries for tax collection.
Fleet Management: Services like Uber use GPS and GIS to track drivers and provide ETAs.
Retail Marketing: Creating customer proximity zones (buffers) around stores.
Supply Chain Logistics: Amazon uses network analysis to optimize delivery routes and minimize costs.
Geology Mapping: Using specific colours and patterns to distinguish rock types.

Timeline

1950s: Municipalities begin vectorizing old hand-drawn city plans for property tax management.
1990-2020: Snapshots used to observe urban growth patterns over decades.
2010: Map data might become temporally inaccurate due to new construction.
2024: Ongoing development and application of GIS technologies, including cloud-based solutions.
2025: Continued advancements in GIS software and hardware, with focus on real-time data and user-friendly interfaces.

People

Jacques Bertin: Developed the 'Semiology of Graphics,' identifying six visual variables for map encoding.