GIS Ch. 1 Notes

Vocabulary flashcards covering core GIS concepts such as data types, models, scales, layers, data quality, and metadata as described in the video notes.

Geographic Information System (GIS)

A system that provides data structures and capabilities for storing, analyzing, managing, and publishing map data using a computer.

Discrete data

Objects with specific locations or boundaries, such as houses, cities, roads, or counties.

Continuous data

Quantities that may be measured anywhere on the Earth, such as temperature or elevation.

Vector model

A data model designed to store discrete data using points, lines, and polygons, each with an associated attribute table.

Raster model

A data model designed to store continuous data as a grid of cells (pixels), each cell holding a value.

Georeferenced

Data tied to a specific location on the Earth’s surface using standardized x-y coordinates.

Geospatial

Data and software used to work with georeferenced information.

Feature

In the vector model, a basic shape (point, line, or polygon) representing a discrete object.

Point feature

A feature representing a single location, such as a well or weather station.

Line feature

A feature representing a linear object like a road or river.

Polygon feature

A feature representing a closed area such as a county or state.

Feature class

A collection of similar features stored together; all features are the same type (points, lines, or polygons).

Layer

A dataset placed into a map; layers are drawn in a stack that determines visibility.

Layer stacking order

Bottom layers are typically raster or polygon; top layers are points or lines so top layers don’t obscure bottom ones.

Cell (pixel)

A small square in a raster that contains a value representing a measured or characteristic quantity.

Spatial resolution

The sampling interval for spatial data, such as the size of a raster cell (e.g., 30 m × 30 m).

Thematic resolution

Resolution of thematic data, such as continuous values versus categorized ranges.

Temporal resolution

How often measurements are taken over time (e.g., census every 10 years, temperature every 15 minutes).

Source scale

The original scale or resolution at which a data set was created or converted to digital form.

Map scale

The ratio showing how map features relate to real-world size; e.g., 1:24,000.

Large-scale map

A map with a large scale ratio (denominator small) showing a small area in detail.

Small-scale map

A map with a small scale ratio (denominator large) showing a large area.

Scale range

A range of display scales for which a data set is valid; used in web maps to show data at different zoom levels.

Metadata

Information about a data set, such as where it came from, how it was developed, who assembled it, how precise it is, and whether it can be shared.

Citing GIS data sources

Ethical practice of crediting data sources in maps and reports; include citations for data sets and their origins.