WPC  2BV[Z #|J2cpi (M)tTddd,Fdp@~rQ@HP LaserJet Series II (Additional)HLSEIIAD.PRSdp@~rQ,t0ZL@#|J2| ZMc]HP LaserJet Series II (Additional)HLSEIIAD.PRSdp@~rQ,t0ZL@"m^,44Xp(88T,4,TXXXXXXXXXX00Xhltth`|x,ThXxhlh\tddhdpHQm,,xDZ] HQRj,,xcy|\Qۢ  Y  C#\2PQP#THE >SPATIAL DATA <TRANSFER STANDARD xA(SDTS) eAPART II   < yx<Rdddy There exists the need for common definitions of spatial features as part of the process of data transfer. Traditional map symbols and their digital code equivalents often refer to real world features which have been defined by cartographers. Feature defintions vary from one organization to the next. Therefore, agreement on a common format for data exchange is not sufficient to ensure that the information provided by the supplier organization will be meaningful or useful to the receiving organization. To facilitate transfer that is meaningful to both exporters and importers, a set of common, well understood definitions is required. )0*0*0*Ԍ  Y SPATIAL FEATURES0hh8@HppQY  axxiPART 2   Yl XPart 2 of the SDTS is the first formal attempt to develop a standardized list of entities.(# XShould be viewed as not "just another list of features and attributes" but again, as a standardized list of features and attributes.(#  < yx<dddy The feature and attribute lists and definitions in Part 2 of the Standard are a first step in the direction of creating a standardized list. These lists and definitions are the product of several years of effort which involved consideration of about 2,600 definitions of geographic features by different organizations with different requirements. Therefore, we emphasize the issue of standardization. X)0*0*0*Ԍ  Y SPATIAL FEATURES0hh8@HppQY  axxiPART 2 XA feature, as defined in the Standard, is made up of an entity (a real world phenomenon that cannot be subdivided into phenomena of the same kind) and its object (the digital representation of all parts of an entity) representation.(#   < yx<dddy To clarify terms: Since different people use the term feature in different ways, the Standard defines a feature as being made up of an entity and its object. An entity is defined as a real world phenomenon that cannot be subdivided into phenomena of the same kind. An object is the digital representation of all parts of an entity. )0*0*0*Ԍ  Y SPATIAL FEATURES0hh8@HppQY  axxiPART 2  Y XATTRIBUTE:0A defined characteristic of an entity type.(#  Y XATTRIBUTE VALUE:` hh8A specific quality or quantity assigned to an attribute.(#h  Pr yxP"dddy  (0*0*0*Ԍ  Y SPATIAL FEATURES 0hh8@HppQY  axxiPART 2  Y INCLUDED TERM hh8Best described as a synonym or specialization that is crossreferenced to an SDTS defined entity or attribute.(#h  P& yxPdddy  Also defined in the Standard:  ~J Standard term: (X0primary label of an entity or attribute.(#  ~J Entity class: (X0a specified group of entities.(#  ~J Attribute class: (X0a specified group of attributes.(# &)0*0*0*Ԍ   Y SPATIAL FEATURES0hh8@HppQPART 2 Example: To grasp the concept of the meaning of a "standardized feature" consider the real world feature "river"   < yx<dddy Z)0*0*0*Ԍ  Y SPATIAL FEATURES0hh8@HppQPART 2 Example: In various regions of the U.S. a river may be referred to as a wash, gulch, stream, creek, kill, run, branch, arroyo, canal, river, etc.  PD yxPdddy  Different organizations as well as different parts of the world are going to define a river differently. It may depend on width or waterflow for example. Some terms related to a river include stream, creek, wash, or canal. h)0*0*0*Ԍ  Y SPATIAL FEATURES 0hh8@HppQPART 2 Example: These terms have been standardized in Part 2: WATERCOURSE as "a way or course through which water may or does flow". Specific types of WATERCOURSE (such as those just mentioned) would be considered attributes.  Pb yxPdddy  (0*0*0*Ԍ  Y SPATIAL FEATURES 0hh8@HppQPART 2  Y ENTITY: (Spring   Y Spring  (Place where water issues from the ground naturally.(# ` `  (Included term Seep  Y ` `  (Attribute hh8Water characteristics  Y ` `  (Attribute value @Hot  P yxP: ddd y R( 0*0*0*Ԍ  Y  SPATIAL FEATURES0hh8@HppQPART 2 First attempt to standardize terms 200 defined entity types 244 defined attributes Over 1,200 included terms Nonhierarchical Extendable  < yx<Pddd y The lists in Part 2 today contain 200 defined entity types, 244 defined attributes, and over 1,200 included terms. It's nonhierarchical and extendable. Evolution of Part 2 In 1982, the National Committee for Digital Cartographic Data Standards (NCDCDS) created four working groups Working Group I for data organization, Working Group II for data quality, Working Group III for cartographic features, and Working Group IV for terms and definitions. The NCDCDS felt that the most pressing problem in digital cartography was that of incompatibility between data bases in terms of data organization, feature classes and codes, coordinate accuracy, metric fidelity, content reliability, and the terms and definitions associated with all of these. The objective of Working Group III was "to examine existing classification of real world features based on federal, state, and local mapping specifications, as well as practices of related professions such as geography, geology, forestry, oceanography, meteorology, etc." They immediately saw the need for explicit feature definitions to enable strict encoding of cartographic features in digital form. Dictionary language and technical geographic terms can be overlapping and circular. To be useful for cartographic classification, a definition must clearly identify which features fit within the definition and which do not. Four major issues in these developments were scale independence, organization, definition, and standard set. Scale independence Since feature classification is an attempt to describe the real world and features in the real world are independent of their cartographic representation and graphic scale, a universal classification system, independent of representation and scale was adopted. For example, a building is a building no matter what symbol or scale is employed. ) 0*0*0*ԌOrganization Because data is not retrieved in the manner in which it is stored, data organization in the data processing sense was not relevant to features. A logical coding scheme not necessarily tied to any existing formal hierarchical or relational model was deemed practical. The design should be openended, flexible and allow for the entry of features and associated attributes. The system can then be accommodated by the organization of the cartographic data base. Definition The theory behind the definitions is that if more than one definition for a feature exists, the differences should be captured in the attributes. The attributes should be multiple and appropriately describe feature characteristics such as structure, composition, mensuration, and serviceability. Thematic features should be classified according to standards for the theme displayed.  R( 0*0*0*Ԍ  Y SPATIAL FEATURES0hh8@HppQPART 2 XCurrently, contains only hydrographic and topographic entities, attributes, and their respective definitions.(# XKnown categories yet to be standardized include geologic, hydrologic, demographic, cadastral, and aeronautical.(#   <( yx<ddd y Standard set Since a standard set of features did not exist, hydrographic charts and topographic maps were selected to supply the initial features for an openended, potentially universal set. Categories to be addressed include geologic, hydrologic, demographic, cadastral and aeronautical. Other issues addressed include collection criteria, feature and attribute classes, tangible existence, pure attributes, collocation and maintenance. ( 0*0*0*Ԍ   Y SPATIAL FEATURES0hh8@HppQPART 2 ` ` TESTING ` `  (Consistency ` `  (Completeness ` `  (Ease of Use   P yxPddd y Finally, the working group conducted a series of tests to indicate applicability of the feature and attribute terms and definitions. They tested for consistency, completeness, and ease of use. Four Federal agencies and four external organizations participated. Consistency Twentyone respondents were given a USGS quadrangle with 51 mapped features circled and numbered. They were asked to identify the features in terms of the standardized lists. Minor changes were made to the defintions to accommodate inconsistencies. Completeness Seventeen respondents were given pages from USGS and National Ocean Survey (NOS) map legends and asked to code the legend items. The goal was to measure whether the domain of topographic map and nautical chart features had been successfully covered in the feature and attribute lists. As a result, a few new features and attributes were added. Ease of use This test consisted of a series of openended questions posed after the two previous tests. The computer printouts were deemed cumbersome. Although feasible to apply, not easy to use. An online data base was proposed. *) 0*0*0*Ԍ  Y SPATIAL FEATURES0hh8@HppQPART 2 Part 2 will be maintained as a "living document" or registry. XThrough the Federal Geographic Data Committee, the USGS will coordinate with other Federal agencies to complete Part 2.(# XProfessional societies, academic institutions, and the private sector are urged to participate.(#  <D yx<dddy That leads us to where we are today. A National spatial features register will be established by NIST and maintained by the USGS. Many questions exist such as who the policy authority will be and how the data base will operate. The USGS will work through the FGDC and coordinate with other Federal agencies in order to expand Part 2. As always, external organizations are urged to participate. Much interest has been expressed to date to help in this effort. (0*0*0*Ԍ