Geometry Tools - Buffer Simplify Clip Geometries Online

Operation

BufferSimplifyClip

Create a buffer zone around geometry at specified distance.

Input Geometry (GeoJSON or WKT)

Operation Options

Buffer Distance

Distance UnitMetersKilometersMilesFeet

Steps (quality)

Tolerance

High Quality

Bounding Box [minX, minY, maxX, maxY]

OR

Clip Polygon (GeoJSON/WKT)

Process Visualize Load Sample Reset

Output Result

What are Geometry Processing Tools?

Geometry processing tools perform spatial operations on geographic features. These operations are fundamental in GIS analysis, cartography, and spatial data processing. This tool provides three essential operations: buffering, simplification, and clipping.

These operations are used extensively in urban planning, environmental analysis, transportation networks, and many other geospatial applications. Understanding how to manipulate geometries is crucial for effective spatial analysis.

Key operations:

• Buffer: Create zones of influence around features (e.g., 500m around a river)
• Simplify: Reduce geometric complexity while preserving shape (Douglas-Peucker algorithm)
• Clip: Extract portions of geometry within a boundary or bounding box
• Visualization: Preview results on interactive map
• Multiple Formats: Support for GeoJSON and WKT input/output

Buffer Operation

Buffering creates a zone of specified distance around a geometry. It's one of the most common spatial operations in GIS analysis.

Buffer parameters:

• Distance: How far the buffer extends from the original geometry
• Unit: Meters, kilometers, miles, or feet
• Steps: Quality of buffer curve (8-64 steps, higher = smoother but more complex)

Common buffer use cases:

• Proximity Analysis: Find areas within distance of a feature (e.g., 1km from subway)
• Impact Zones: Determine area affected by pollution, noise, or other factors
• Service Areas: Identify coverage areas for facilities or services
• Setback Regulations: Enforce minimum distance requirements in planning

Simplify Operation (Douglas-Peucker)

Simplification reduces the number of vertices in a geometry while preserving its general shape. The Douglas-Peucker algorithm is the industry standard for line and polygon simplification.

Simplification parameters:

• Tolerance: Maximum distance a simplified point can deviate from original (lower = more detail)
• High Quality: Uses more computation for better results (optional)

When to use simplification:

• Map Display: Reduce detail for faster rendering at small scales
• Data Storage: Decrease file size for large datasets
• Web Performance: Optimize geometries for web mapping applications
• Generalization: Create appropriate level of detail for different zoom levels

Note: Tolerance is in degrees for geographic coordinates or in the units of projected coordinates. Start with small values (0.0001-0.001 for degrees) and increase as needed.

Clip Operation

Clipping extracts the portion of a geometry that falls within a specified boundary. This is also known as 'cookie cutting' or 'spatial intersection'.

Clip methods:

• Bounding Box: Clip by rectangular extent [minX, minY, maxX, maxY]
• Polygon: Clip by custom polygon boundary (supports complex shapes)

Common clipping use cases:

• Study Area Extraction: Extract data for specific region of interest
• Administrative Boundaries: Clip features to country, state, or city limits
• Data Subsetting: Create smaller datasets from large geographic datasets
• Map Production: Prepare data to fit specific map extents

Algorithm Details

Douglas-Peucker Algorithm:

The Douglas-Peucker algorithm works by recursively dividing a line and removing points that fall within a specified tolerance of the line segment. It's efficient and produces excellent results for most geometries.

• Step 1: Draw line from first to last point
• Step 2: Find point farthest from this line
• Step 3: If distance >tolerance, keep point and recurse on segments
• Step 4: If distance ≤ tolerance, remove all points in between

Best Practices

Tips for effective geometry processing:

• Buffer: Use appropriate units for your data (meters for local, degrees for global)
• Simplify: Test different tolerances to find the right balance between detail and size
• Clip: Validate your clipping boundary is in the same coordinate system
• Performance: Simplify complex geometries before other operations
• Validation: Always visualize results to ensure they meet your requirements

These operations can be combined: for example, buffer a line, then clip to study area, then simplify for web display.