Full text: XVIIIth Congress (Part B2)

  
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Topological data types include AREA (closed polyline), 
LINE (open polyline), POINT (single point) and WINDOW 
(rectangle parallel to coordinate system axis). Additional 
operators (.X. , .«. , .». , ...) allow for intersection and 
selection of geometric/topological data sets. 
Communication between TOPDB and an application is 
done by a data base language called ,TOPSQL Its 
current functionality is on the one hand a subset of ANSI- 
SQL but on the other hand an extension regarding the 
geometric/topological data types and operators. 
A typical data selection could be to extract all data from a 
specified table, which are at least partly inside a given 
area, which have an accuracy for heights better than 30 
cm and have been compiled later than 1985-10-20. 
These query can be formulated by using TOPSQL. 
SELECT * FROM DHMDATA 
WHERE (COORDINATES .X. AREA (10000 50000 
15000 60000 
20000 40000) 
AND (ZACCURACY « 0.30) 
AND (COMPILEDATE » 20.10.1985); 
5.3 Table System 
For storing, managing and archiving topographic data a 
complex system of tables is used. Several types of 
different tables have been defined to describe the 
structure of a table and the data type for each column of 
the table. In SCOP.TDM about two dozens of different 
table types are involved. Most of them serve only for 
internal organizational or summary purposes, but a few 
of them are of interest for the user. This includes tables 
for storing topographic data, tables for controlling 
translation of coding information during data import and 
export and vocabulary tables. 
5.3.1 Tables for Storage of Topographic Data: The 
most important tables are of type TDXYZTAB. Such 
tables are used to store and manage arbitrarily 
distributed topographic data. A data set in one of these 
tables corresponds to exactly one terrain object 
represented by a series of 3-dimensional coordinates and 
additional data properties. The full definition of a table of 
type TDXYZTAB is shown in table 1. 
  
IDOBJ INTEGER UNIQUE INDEX NOT NULL  SYSNUM 
IDENTIFIER 
DATAFORMAT CHAR (16) INDEX NOT NULL 
AGGREGATE CHAR (16) INDEX NOT NULL 
OBJECTNAME CHAR(16) INDEX NOT NULL 
OBJECTTYPE CHAR(16) INDEX NOT NULL 
COORDINATES LINE INDEX NOT NULL  PERIOD(3) 
RESOLUTION(2,2,2) 
FEATURECODE  CHAR(32) INDEX NULL 
STATUS CHAR(16) INDEX NULL 
XYACCURACY NUMBER (12.2) INDEX NULL 
ZACCURACY NUMBER (12.2) INDEX NULL 
CREATOR CHAR (32) INDEX NULL 
OWNER CHAR (32) INDEX NULL ARRAY 
COMPILEMODE CHAR (32) INDEX NULL 
PROPERTIES CHAR(32) INDEX NULL ARRAY 
COMPILEDATE DATE INDEX NULL 
COMPILETIME TIME INDEX NULL 
INSERTDATE DATE INDEX NOT NULL 
INSERTTIME TIME INDEX NOT NULL 
UPDATEDATE DATE INDEX NULL 
UPDATETIME TIME INDEX NULL 
  
Table 1: Definition of Table Type TDXYZTAB 
For each column the name of the column, the data type, 
indexing instructions and other attributes are listed. This 
definition includes a list of coordinates (COORDINATES), 
an object meaning (FEATURECODE), the type of an 
object (OBJECTTYPE), an object name (OBJECT- 
NAME), the objects original data format (DATA- 
FORMAT), information about accuracy in planimetry and 
height (XYACCURACY, ZACCURACY), the name of the 
organization responsible for data compilation 
(CREATOR), a list of authorized data users (OWNER), 
information about the compilation method (COMPILE- 
MODE), a list of additional properties (PROPERTIES) 
and information about date and time of data compilation 
(COMPILEDATE, COMPILETIME). 
5.3.2 Data Format Code Conversion Tables: Topo- 
graphic data are read in from files organized according to 
commonly used data formats (WINPUT, DXF, ARC/INFO 
Generate, ...) and are stored in topographic data tables. 
This process is called ,data import". The opposite 
operation is to extract data from topographic data tables 
and to write these data to files. This is called ,data 
export". 
In both cases it is necessary to translate coding 
information from the external data representation format 
to the native representation and vice versa. These 
translations are controlled by data format code 
conversion tables, which are set up by the user. The 
structure of a data format code conversion table depends 
on the individual data format. Table 2 gives an example 
for DXF. During the IMPORT process the coding pair for 
an object in DXF (LAYER, ENTITY) is mapped to a pair 
used in tables of type TDXYZTAB (FEATURECODE, 
OBJECTTYPE). When exporting data the reverse 
mapping is done. 
  
IDCDXF INTEGER UNIQUE INDEX NOT NULL  SYSNUM 
IDENTIFIER 
FEATURECODE CHAR(32) INDEX NOT NULL 
OBJECTTYPE CHAR (16) INDEX NOT NULL 
ENTITY CHAR (12) INDEX NOT NULL 
LAYER CHAR (32) INDEX NOT NULL 
COMMENT STRING NULL 
  
162 
Table 2: Definition of Table Type CVDXFTAB 
5.3.3 Vocabulary Tables: On many occasions assign- 
ment of names or other terms is necessary when using 
SCOP.TDM. Examples are names of authorized data 
users, names of coordinate systems or feature codes. To 
ensure a systematic usage of such names, a global 
name space can be set up in vocabulary tables as basis 
for checking user input. Furthermore consistency in 
spelling and using names is advantageous when 
specifying conditions for data selection. 
5.4 Topographic Data Market and Archive 
All tables for storing topographic data together with meta- 
information and additional organizational and summary 
tables are placed in a disk area, which is called 
„Topographic Data Market“. This area is permanently 
available on the disk. It is the market place for all 
activities concerning data import and data export. DTM 
application programs may access these data too. 
Long-term storage and archiving of topographic data is 
done in the ,Topographic Data Archive". Topographic 
data can either be copied or moved from the data market 
to the data archive . 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B2. Vienna 1996 
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