Surface Analysis
Definition
Surface analysis derives information from continuous fields such as elevation, temperature, pollution, or cost. Operations include slope, aspect, curvature, hillshade, contouring, viewshed, watershed delineation, least-cost paths, and raster algebra. Resolution, interpolation method, and edge handling govern accuracy. Surface models support both descriptive mapping and predictive simulations.
Application
Planners assess visual impact; engineers compute earthwork volumes; ecologists evaluate habitat suitability; and emergency managers simulate fire spread or flood routing. Businesses build travel-time and service surfaces for accessibility planning.
FAQ
How do cell size and neighborhood choices affect derivatives?
Larger cells smooth variability; small windows capture detail but amplify noise. Choose parameters aligned with decision scales and data quality.
What precautions apply to viewshed analysis?
Use surface models appropriate to the question (bare earth vs surface), include earth curvature and refraction when needed, and validate with field observations.
How is cost-distance different from Euclidean distance?
Cost-distance accumulates travel impedance across cells (slope, land cover, barriers), producing realistic paths and times, whereas Euclidean assumes straight lines.
Why is edge effect awareness important?
Derivatives near dataset boundaries can be biased due to missing neighbors; pad with context or interpret cautiously.