Terrain Analysis and GIS Modeling Techniques

Elevation

Digital raster layer of elevation

Slope

Rise over run

Slope as degrees

tan-1(A/B)

Aspect

Creating it into a compass or circle

Pit

Lower elevation surrounded by higher elevation

Peak

Water will flow away from the peak

Saddle

Not defined in the notes

Viewshed

Visibility of locations

Process

Defined viewing origins

Spatial estimation

Interpolation

Sampling

Systematic, random, adaptive, clustered

TIN

Triangulated irregular network

Delaunay triangles

Join nearest points, as equiangular as possible, longest side as short as possible

Thiessen polygons

Created by perpendicular bisection of connecting triangle sides between points

Inverse distance weighted (IDW)

z' determined by a fixed number of z points; Weight → 1/dk - d = distance, k = power

Spline

Algorithm adapts to where you are on the map

Resolution

Spatial resolution: The smallest area of detail in the map

Radiometric resolution

The smallest difference in energy that can be detected by the sensor

Spectral Resolution

The fineness of a wavelength interval

Semantic resolution

Anderson classification system: Lower resolution, more general categories

Data sources

National map, Multi-resolution land characteristic, Bureau of land management, National agricultural statistic service

Change analysis

Applications include land use/cover, atmospheric data, cropland, forest canopy, impervious surface, fire-affected area detection

Detection research information

Area change, change rate, spatial distribution of changed types, changed trajectories

Model

Description of reality

Modeling

Cartographic/spatial model expresses a process or pattern as a set of GIS operations

Revised Universal Soil Loss Equation

E = R K C P L * S

Gross primary productivity

GPP = Conversion efficiency NDVI PAR

Python

Program - sequence of instructions that specifies how to perform a computation

Spatial Data Infrastructure (SDI)

Recognized by the White House, it's an infrastructure itself

Web Services

REST - Representational state transfer; allows for transfer of data between applications

Point

0 dimensional geometric object and represents a single location in space; has x, y, z, m

Saddle

A landform that connects two higher elevations.

Viewshed

Visibility of locations defined by viewing origins.

Process

Defined viewing origins, draw rays from the origin to every cell.

Spatial estimation

Interpolation, insert something between fixed points.

Sampling

Systematic, random, adaptive, clustered.

TIN

Triangulated irregular network made up of Delaunay triangles.

Delaunay triangles

Join nearest points, as equiangular as possible, longest side as short as possible.

Thiessen polygons

Created by perpendicular bisection of connecting triangle sides between points.

Nearest neighbor (Thiessen)

Each point z' within polygon is closest to that polygon's control point (z).

Fixed radius

Local averaging to determine the center of the pixel.

Inverse distance weighted (IDW)

z' determined by a fixed number of z points, weight → 1/dk where d = distance, k = power.

Spline

Algorithm adapts to where you are on the map.

Resolution

Spatial resolution is the smallest area of detail in the map.

Radiometric resolution

The smallest difference in energy that can be detected by the sensor.

Spectral Resolution

The fineness of a wavelength interval.

Semantic resolution

Anderson classification system, lower resolution, more general categories.

Interoperability

Includes spatial, radiometric, temporal, spectral, and semantic/attribute.

Data sources

National map, multi-resolution land characteristic, Bureau of land management, National agricultural statistic service.

Change analysis

Applications include land use/cover, atmospheric data, cropland, forest canopy.

Detection research information

Includes area change, change rate, spatial distribution of changed types.

Techniques

Algebra, transformation, classification, advance GIS, visual, image difference, change matrix.

Model

Description of reality, 'All models are wrong, but some are useful'.

Modeling

Cartographic/spatial model expresses a process or pattern as a set of GIS operations.

Python

A sequence of instructions that specifies how to perform a computation.

Benefits of Python

Speed up time-consuming tasks, write programs that prewritten software can't do.

Spatial Data Infrastructure (SDI)

Recognized by the White House, it's an infrastructure itself.

GIS standards

Includes data standards, interoperability standards, analysis standards.

SDI components

Data and attributes, documentation/metadata, ability to discover, visualize and evaluate data.

GeoPlatforms Capabilities

Interoperability, cloud computing, multi-agency purchase and access.

Web Services

REST - Representational state transfer allows for transfer of data between applications.

Point

0 dimensional geometric object representing a single location in space, has x, y, z, m.

Boundary of a point

The empty set - there is no boundary to a point.