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1 Scale

[mathematics] An affine transformation changes points, polylines, polygons in a plane by scaling, rotating, skewing, or translating coordinates in two or three-dimensional spaces.

2 Scale (measurement)

a system used to encode the results of a measurement; typically a number line, but generalized to include a list of categories.

3 Scale Bar

[mathematics] A scale bar graphically shows the distance on the map with units such as kilometers or meters. Scale bars are proportional to the scale of the map.

4 Scanner

A device for converting images from maps, photographs, or from part of the real world into digital form automatically.

5 Selection Tool

[GIS processing] The selection tool identifies an object or set of objects based on user-selected criteria and properties, typically with Structured Query Language (SQL).

6 Shaded Relief

[remote sensing] A shaded relief map displays the brightness and shadows of terrain reflection given a sun angle and direction of sunlight.

7 Sidelap

[remote sensing] Sidelap (or side overlap) consists of the overlapping edge areas of photographs between adjacent flight lines.

8 Skeletonize

 [GIS processing] Skeletonizing is the process of thinning a raster line to a single pixel width, typically for conversion to vector data format.

9 Snapping Environment

[editing] The snapping environment in GIS determines the distance that newly digitized points, lines and polygons will occupy the same location of existing features.

10 Soils

Soil data consist of georeferenced digital map data and associated tabular attribute data. The map data describe the spatial distribution of the various soils that cover Earth’s surface. The attribute data describe the proportionate extent of the various soils, as well as the physical and chemical characteristics of those soils. The physical and chemical properties are based on observed and measured values, as well as model-generated values. Also included are model-generated assessments of the suitability or limitations of the soils to various land uses.

Source: OMB Circular A–16: Appendix E (2002)

Category: NSDI Data Themes (NDT)

11 Spaghetti Data Model

[data structure] The spaghetti data model is a simple GIS model where lines may cross without intersecting or topology and usually no attributes are created.

12 Spatial Analysis

The process of modeling, examining, and interpreting model results. Spatial analysis is useful for evaluating suitability and capability, for estimating and predicting, and for interpreting and understanding. 

13 Spatial autocorrelation

degree of correlation between a surface value and the values of its neighbors; propensity of spatial data to vary smoothly.

14 Spatial object framework

a measurement framework that identifies a particular category, then maps the location of that object (as a point, a line or an area).

15 Spatial reference system

a mechanism to situate measurements on a geometric body, such as the Earth; establishes a point of origin, orientation of reference axes, and geometric meaning of measurements, as well as units of measure. [basis of coordinates.]

16 Spatial Relationship

[data structure] A spatial relationship links GIS features with a table by a unique identifier all stored in a relational database management system.

17 Spherical Coordinates

[coordinate system] Spherical coordinates is a coordinate system based on a sphere defined by two angles of rotation in orthogonal planes. The most common is latitudes and longitudes in a geographic coordinate system.


An earth resource satellite with high resolution sensors launched by France in January 1986.

19 SQL

Structured Query Language; a standard interface for access to a relational database through queries that select records matching logical expressions.

20 Stakeholders

Such as Federal Public Service, Federal Statutory Bodies, State Public Service, State Statutory Bodies, Local Authorities and Private Sector.

21 State Plane Coordinates:

[coordinate system] State Plane Coordinates is a standardized system in the United States based on Lambert conformal conic and transverse Mercator projections.

22 Stereo Pairs

[remote sensing] Stereo pairs are overlapping photos taken at different positions but of the same area. Parallax is used to interpret height differences within the overlapping area.

23 Stereographic Projection

[map projection] A stereographic projection is a mapping function that projects an entire sphere on a plane – except at one point: the projection point.

24 Structured Query Language (SQL)

[map projection] SQL is a set of commands used to manage data stored in relational database management systems (RDBMS).

25 Surface

a spatial distribution which associates a single value with each position in a plane; (technically a field of a single-valued function) usually associated with continuous attributes.

26 Survey Station

[surveying] A position where surveys are performed from. During land surveys, survey stations make accurate measurements on the ground from these positions.


27 Symbology

Symbology, in the context of Cartographic design, is the use of graphical techniques to represent geographic information on a map. Map symbols for geographic features include Visual variables such as color, size, and shape.