# Presentation: 365304

## The Spatial Data Transfer Standard (SDTS)

**Part 1**
**Volume 1 of 2**

**05/19/94**

## SDTS Part 1

**A Conceptual Model of Spatial Data**
**Specifications for a Data Quality Report**
**Logical Transfer Format Specifications**

## SDTS Part 1

**A Conceptual Model of Spatial Data**
**Spatial Phenomena (Sect 2.1.1)**
**Entities, Attributes, and Attribute Values**
**Spatial Objects (Sect 2.1.2)**
**The Digital Representation of Entities**
**Spatial Features (Sect. 2.1.3)**
**Both Entity (*****phenomena*****) and Object (*****representation*****)**

## SDTS Feature (model)

**FEATURE = A Defined Entity and Its Object Representation**

_**Entity**_
**A real world phenomenon**

_**Object**_
**A digital representation of all or part of an entity**

## Spatial Objects

**0 Dimensions**

**1 Dimension**

**2 Dimensions**

**Point**

**Node**

**Line Segment**

**String**

**Link**

**Arc**

**Chain**

**G-Ring**

**G-Polygon**

**GT-Polygon**

**Pixel**

**Grid Cell**

**Geometry**
**Only**

**Geometry &**
**Topology**

**GT-Ring**

## Definition of Zero-Dimensional Spatial Objects

**POINT (NP)**
**A zero-dimensional object that specifies geometric location.  One coordinate pair or triplet specifies the location.**

**(X,Y)**
**(X,Y,Z)**

## Definition of Zero-Dimensional Spatial Objects

**The point definitions that follow are special implementations of the general case.**
**ENTITY POINT (NE)**
**A point used for identifying the location of point features (or areal features collapsed to a point) such as towers, buoys, buildings, places, etc.**

## Definition of Zero-Dimensional Spatial Objects

**LABEL POINT (NL)**
**A point used for displaying map and chart text (e.g., feature names) to assist in feature identification.**
**AREA POINT (NA)**
**A point within an area usually carrying attribute information about the area.**

## Definition of Zero-Dimensional Spatial Objects

**Node (NO, NN)**
**A zero-dimensional object that is a topological junction of two or more links or chains or an end point of a link or chain.**
**NO****	****Node, planar graph**
**NN****	****Node, network**

## Definition of One-Dimensional Spatial Objects

**A line is a generic term for a one-dimensional object.**
**Line segment**
**A direct line between two points.**

## Definition of One-Dimensional Spatial Objects

**STRING (LS)**
**An ordered sequence of points representing a connected nonbranching sequence of line segments.**
**Note: A string may intersect itself or other strings.**

## Definition of One-Dimensional Spatial Objects

**ARC (AC, AE, AU, AB)**
**A locus of points forming a curve defined by a mathematical function.**

## Definition of One-Dimensional Spatial Objects

**LINK (LQ)**
**Topological connection between two nodes.  A link may be directed by ordering its nodes.**

## Definition of One-Dimensional Spatial Objects

**CHAIN**
**A directed non branching sequence of nonintersecting line segments and/or arcs bounded by nodes, not necessarily distinct, at each end.**
**The following three objects are special cases of chains.  They share all characteristics of the general case as defined above.**

## Definition of One-Dimensional Spatial Objects

**COMPLETE CHAIN (LE)**
**A chain that explicitly references left and right polygons and start and end nodes.  It is a component of a two-dimensional manifold.**

**Start**
**Node**

**End**
**Node**

**Left Polygon**

**Right Polygon**

## Definition of One-Dimensional Spatial Objects

**AREA CHAIN (LL)**
**A chain that explicitly references left and right polygons and ****not**** start and end nodes.  It is a component of a two-dimensional manifold.**

**Left Polygon**

**Right Polygon**

## Definition of One-Dimensional Spatial Objects

**NETWORK CHAIN (LW, LY)**
**A chain that explicitly references start and end nodes and ****not**** left and right polygons.  It is a component of a network**
**LW****	****Network chain (planar graph)**
**LY ****	****Network chain (nonplanar graph)**

**Start**
**Node**

**End**
**Node**

## Definition of One-Dimensional Spatial Objects

**RING**
**A sequence of nonintersecting chains or strings and (or) arcs, with closure.  A ring represents a closed boundary, but not the interior area inside the closed boundary.**

## Definition of One-Dimensional Spatial Objects

**G-RING (RS, RA, RM)**
**A ring created from strings and (or) arcs.**
**RS     Ring of Strings**
**RA     Ring of Arcs**
**RM    Ring with mixed**

## Definition of One-Dimensional Spatial Objects

**GT-RING (RU)**
**A ring created from complete and/or area chains.**

**Chain 11**

**Chain 47**

**Chain 55**

## Definition of Two-Dimensional Spatial Objects

**An area is a generic term for a bounded continuous, two-dimensional object that may or may not include its boundary.**
**Interior Area**
**An area not including its boundary.**

## Definition of Two-Dimensional Spatial Objects

**G-POLYGON (PG)**
**An area consisting of an interior area, one outer G-ring and zero or more nonintersecting, nonnested inner G-rings.  No ring, inner or outer, shall be collinear with or intersect any other ring of the same G-polygon.**

## Definition of Two-Dimensional Spatial Objects

**GT-POLYGON (PR,PC)**
**An area that is an atomic two-dimensional component of one and only one two-dimensional manifold.**
**PR****	****GT-POLYGON composed of rings**
**PC ****	****GT-POLYGON composed of chains**

## Definition of Two-Dimensional Spatial Objects

**UNIVERSE-POLYGON (PU,PW)**
**Defines the part of the universe outside the perimeter of the area covered by other GT-polygons (“covered area”) and completes the two-dimensional manifold.  This polygon completes the adjacent relationships  of the perimeter links.**
**PU****	****	****UNIVERSE-POLYGON composed of rings**
**PW****	****UNIVERSE-POLYGON composed of chains**

## Definition of Two-Dimensional Spatial Objects

**Definition of Two-Dimensional Spatial Objects**

**UNIVERSE-POLYGON (continued)**
**The boundary of the universe polygon is represented by one or more inner rings and no outer ring.**

**Universe**

## Definition of Two-Dimensional Spatial Objects

**VOID POLYGON (PV, PX)**
**Defines a part of the two-dimensional manifold that is bounded by other GT-polygons, but otherwise has the same characteristics as the universe polygon.**
**The geometry and topology of a void polygon are those of a GT-polygon.  **
**PV****	****VOID POLYGON composed of rings**
**PX****	****VOID POLYGON composed of chains**

## Definition of Two-Dimensional Spatial Objects

## Definition of Two-Dimensional Spatial Objects

**PIXEL**
**A two-dimensional picture element that is the smallest nondividible element of an digital image.**

## Definition of Two-Dimensional Spatial Objects

**GRID CELL**
**A two-dimensional object that represents the smallest nondivisible element of a grid.**

## Definition of Two-Dimensional Spatial Objects

**LABELED GRID CELL**
**A two-dimensional object that represents the smallest nondivisible element of a labeled grid.**

**Y-label ----**

**X-label**

**NEW**
**in V2.0**

## VOXEL

**A quantum unit of volume that represents some measurable properties or independent variables of a phenomenon. Smallest divisible element of a voxel space**

**Definition of Three-Dimensional Spatial Objects**

**NEW**
**in V2.0**

## LABELED VOXEL

**Smallest divisible element of a labeled voxel space.**

**Definition of Three-Dimensional Spatial Objects**

**NEW**
**in V2.0**

**Y-label**

**Z-label**

**X-label**

## 2-D with N-dim Grid Cell

**2-D with N-dim Labeled Grid Cell**
**3-d with N-dim Grid Cell**
**3-D with N-dim Labeled Grid Cell**

**Definition of Spatial Objects with Nongeospatial Dimensions**

**NEW**
**in V2.0**

**Advanced raster capability needed for**
**certain types of scientific spatial data.**

## Definition of 2-D Aggregate Spatial Objects

**Certain aggregate spatial objects must be defined to provide context for many of the simple objects defined above.  **
**raster objects: grid, image, labeled grid**
**topology objects: (graphs, with or without geometry)**

## Aggregations

**Digital Image**
**Grid **
**Layer**
**Raster**
**Graphs**
**Planar Graph**
**2-D Manifold**
**Network**

## Definition of Aggregate Spatial Objects

**DIGITAL IMAGE**
**A two-dimensional array of regularly spaced elements constituting a picture.**

## Definition of Aggregate Spatial Objects

**GRID (GI, GJ, GK, GM)**
**A regular, or nearly regular, tessellation of a surface.  The tessellation is regular if formed by repeating the pattern of a regular polygon, such as a square, equilateral triangle, or regular hexagon.**

## Definition of Aggregate Spatial Objects

**Layer**
**An integrated, areally distributed set of spatial data representing instances within one theme, or having one common attribute or attribute value in an association of spatial objects.**

## Definition of Aggregate Spatial Objects

**LAYER**
**In the context of raster data, a layer is specifically a two-dimensional array of attribute values associated with all or part of a grid.**

## Definition of Aggregate Spatial Objects

**RASTER**
**A number of overlapping layers for the same grid or image.**

## Definition of Aggregate Spatial Objects

**GRAPH**
**A set of topologically interrelated zero-dimensional (node), one-dimensional (link, or chain), and sometimes, two-dimensional (GT-polygon) objects that conform to a set of defined constraint rules.**
**Each link or chain is bounded by an ordered pair of nodes, not necessarily distinct.**
**A node may bound one or more links or chains.**
**Links or chains may only intersect at nodes.**

## Definition of Aggregate Spatial Objects

**PLANAR GRAPH (GP)**
**The node and link or chain objects of the graph occur or can be represented as though they occur upon a planar surface. Not more than one node may exist at any given point on the surface.  Links or chains may only intersect at nodes.**

## Definition of Aggregate Spatial Objects

**TWO-DIMENSIONAL MANIFOLD (GT)**
**A planar graph and its associated two dimensional objects. Each chain bounds two and only two, not necessarily distinct, GT-polygons. The GT-polygons are mutually exclusive and completely exhaust the surface.**

## Definition of Aggregate Spatial Objects

**Definition of Aggregate Spatial Objects**

**NETWORK (GN)**
**A graph without two dimensional objects. If projected onto a two-dimensional surface, a network can have either more than one node at a point and/or intersecting links or chains without corresponding nodes.  **

## Definition of Aggregate Spatial Objects

**2-D: Labeled Grid**
**3-D: Voxel Space**
**3-D: Labeled Voxel Space**
**2-D with N-dim Grid**
**2-D with N-dim Labeled Grid**
**3-D with N-dim Grid**
**3-D with N-dim Labeled Grid**

**NEW**
**in V2.0**

## SDTS Part1, Spatial Objects

**Section 2.3 - these definitions and figures**
**Version 2.0 - ANSI Submission - Advanced Raster Capabilities**
**Section 5.7 - more information on Raster**
**Annex E: Raster Examples**