DATA MANAGEMENT IN GIS SPATIAL (GEO) DATA MODELS NON SPATIAL (RELATIONAL) DATA MODELS GEO-RELATIONAL MODEL By Prof. V L. Swaminathan

DATA COMPONENTS IN GIS G E O G R A P H I C D A T A T1 T2 Temporal Dimension LOCATIONAL DATA (Spatial) NON-LOCATIONAL (Description) T1 T2 Measured x-y Topological Relation Var Class Val Name Point Line Poly Grid Net. Soil 1. Sand ...... ... 1.1 Fine ...... ... 1.2 Coarse

SPATIAL DATA MODELING DIGITAL MODEL GIS DATABASE MODEL MAP RASTER REAL WORLD ELLIPSOID DIGITAL MODEL GIS DATABASE MODEL SPHEROID ANALOG MODEL MAP RASTER VECTOR

VECTOR SPAGHETTI STRUCTURE 11 31 6 15 (0,0) X AXIS Y Feature No. Location Point 6 x,y (Single Point) Line 11 x1,y1;x2,y2;...xn,yn Polygon 31 x1,y1;x2,y2;...xn,yn Polygon 15 x1,y1;x2,y2;...xn,yn

VECTOR SPAGHETTI : Critique-1 Feature No. Location Point 6 x,y (Single Point) Line 11 x1,y1;x2,y2;...xn,yn Polygon 31 x1,y1;x2,y2;...xn,yn Polygon 15 x1,y1;x2,y2;...xn,yn 11 31 6 15 (0,0) X AXIS Y CAPTURES LOCATIONS ACCURATELY BUT: SHARED BOUNDARIES OF POLYGON 31 & 15 CAPTURED MORE THAN ONCE. IN REALITY SUCH REPETITIONS WILL BE MANY. PROBLEMS OF INTEGRITY, AND REDUNDANCY IN DATABASE

VECTOR SPAGHETTI : Critique-2 Feature No. Location Point 6 x,y (Single Point) Line 11 x1,y1;x2,y2;...xn,yn Polygon 31 x1,y1;x2,y2;...xn,yn Polygon 15 x1,y1;x2,y2;...xn,yn 11 31 6 15 (0,0) X AXIS Y POLYGON 31 IS INCLUDED IN 15 . LINE 11 AND POINT 6 ARE ALSO WITHIN POLYGON 15. IN REALITY SUCH RELATIONSHIPS ARE MANY. SPATIAL RELATIONSHIPS HAVE TO BE COMPUTED GEOMETRICALL AND INFERRED IMPLICATIONS ON COMPUTATIONAL EFFICIENCY

VECTOR TOPOLOGY STRUCTURE 1 2 5 3 4 6 7 8 9 10 11 NODE LINK POLYGON LINK# R-POLY L-POLY NODE-1 NODE-2 1 1 0 3 1 2 2 0 4 3 3 2 1 3 2 4 1 0 1 2 5 3 2 4 2 6 3 0 2 5 7 3 3 5 6 8 4 3 6 4 9 5 4 7 6 ...... ..... .... NODE# X_COORD Y_CORD 1 23 8 2 17 17 3 29 15 4 26 21 5 8 26 6 22 30 7 24 38

VECTOR TOPOLOGY STRUCTURE : CRITIQUE -1 2 5 3 4 6 7 8 9 10 11 NODE LINK POLYGON LINK# R-POLY L-POLY NODE-1 NODE-2 1 1 0 3 1 2 2 0 4 3 3 2 1 3 2 4 1 0 1 2 5 3 2 4 2 6 3 0 2 5 7 3 3 5 6 8 4 3 6 4 9 5 4 7 6 ...... ..... .... NODE# X_COORD Y_CORD 1 23 8 2 17 17 3 29 15 4 26 21 5 8 26 6 22 30 7 24 38 CAPTURES CO-ORDINATES ONLY ONCE PROBLEMS OF REDUNDANCY AND INTEGRITY MINIMIZED

VECTOR TOPOLOGY STRUCTURE : CRITIQUE -2 1 2 5 3 4 6 7 8 9 10 11 NODE LINK POLYGON LINK# R-POLY L-POLY NODE-1 NODE-2 1 1 0 3 1 2 2 0 4 3 3 2 1 3 2 4 1 0 1 2 5 3 2 4 2 6 3 0 2 5 7 3 3 5 6 8 4 3 6 4 9 5 4 7 6 ...... ..... .... CAPTURES SPATIAL RELATIONSHIPS EXPLICITLY ASSOCIATION AMONGST THE SPATIAL FEATURES CONNECTIVITY

VECTOR TOPOLOGY STRUCTURE : CRITIQUE -3 1 2 5 3 4 6 7 8 9 10 11 NODE LINK POLYGON LINK# R-POLY L-POLY NODE-1 NODE-2 1 1 0 3 1 2 2 0 4 3 3 2 1 3 2 4 1 0 1 2 5 3 2 4 2 6 3 0 2 5 7 3 3 5 6 8 4 3 6 4 9 5 4 7 6 ...... ..... .... ASSOCIATION FOR FINDING POLYGONS SURROUNDING 3, SEARCH THROUGH THE LIST LOOK FOR LINKS BOUNDING THE POLYGON-3 LOOK FOR ASSOCIATED R-POLY & L-POLY

VECTOR TOPOLOGY STRUCTURE : CRITIQUE -4 1 2 5 3 4 6 7 8 9 10 11 NODE LINK POLYGON LINK# R-POLY L-POLY NODE-1 NODE-2 1 1 0 3 1 2 2 0 4 3 3 2 1 3 2 4 1 0 1 2 5 3 2 4 2 6 3 0 2 5 7 3 3 5 6 8 4 3 6 4 9 5 4 7 6 ...... ..... .... CONNECTIVITY : NODE-7 & NODE-2 LOOK FOR LINKS EMNATING FROM NODE-7 i.e 9, 11,10 FOCUS ON ONE LINK(i.e. 9) AND LOOK FOR ASSOCIATED NODES (i.e 6) LOOK FOR LINKS EMNATING FROM THIS NODE (i.e. 8,7) CONTINUE THE PROCESS TILL NODE 2 IS REACHED FOR ALL THE PASSES

VECTOR TOPOLOGY STRUCTURE : CRITIQUE -5 1 2 5 3 4 6 7 8 9 10 11 NODE LINK POLYGON LINK# R-POLY L-POLY NODE-1 NODE-2 1 1 0 3 1 2 2 0 4 3 3 2 1 3 2 4 1 0 1 2 5 3 2 4 2 6 3 0 2 5 7 3 3 5 6 8 4 3 6 4 9 5 4 7 6 ...... ..... .... NODE# X_COORD Y_CORD 1 23 8 2 17 17 3 29 15 4 26 21 5 8 26 6 22 30 7 24 38 BY EXPLICITLY CAPTURING SPATIAL RELATIONSHIPS (i.e. TOPOLOGY GEOMETRIC COMPUTATION PROBLEM IS TURNED INTO SEARCH PROBLEM

RASTER GRID STRUCTURE 1 2 3 4 File Structure: 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 0 1 1 1 1 1 1 0 1 1 1 1 1 0 0 1 1 1 1 1 1 1 0 0 1 1 1 1 0 1 2 3 4 File Structure: Row Column Value 1 1 0 1 2 0 . . . 2 1 1 2 2 1 Row Column Value 3 1 1 3 2 1 . . . 4 1 1 .. .. ..

RASTER GRID : Critique-1 0 0 0 0 0 0 0 1 1 1 1 1 1 0 1 1 1 1 1 1 0 1 1 1 1 1 0 0 1 1 1 1 1 1 1 0 0 1 1 1 1 0 1 2 3 4 LINE AND POINT NOT REPRESENTED: SEPEARATE LAYERS REQUIRED FOR OVERLAPPING FEATURES POLYGONS, POINTS AND LINES

RASTER GRID : Critique-2 0 0 0 0 0 0 0 1 1 1 1 1 1 0 1 1 1 1 1 1 0 1 1 1 1 1 0 0 1 1 1 1 1 1 1 0 0 1 1 1 1 0 1 2 3 4 0’S AND 1’S REPEATED MANY TIMES UNNECESSARILY REDUNDANCY OF DATA STORAGE IMPLICATIONS ON STORAGE VOLUME SOLUTION RUN LENGTH ENCODING ROW COLUMN VAL 1 1-7 0 2 1-6 1 2 7 0 ...... .... ...

RASTER GRID : Critique-2 0 0 0 0 0 0 0 1 1 1 1 1 1 0 1 1 1 1 1 1 0 1 1 1 1 1 0 0 1 1 1 1 1 1 1 0 0 1 1 1 1 0 1 2 3 4 POLYGON 2 NOT REPRESENTED: GRID SIZE HAS TO BE SMALLER IN ORDER TO REPRESENT FEATURES ACCURATELY - IMPLICATIONS ON STORAGE VOLUME OR HAVE VARIABLE SIZE OF GRID OVERLAY : QUAD-TREE

QUAD-TREE STRUCTURE RASTER QUADTREE AREA RECURSIVELY DECOMPOSED INTO REGULAR SHAPED GRIDS OF SMALLER & SMALLER SIZE TILL SMALLEST GRID REPRESENTS HOMOGENEOUS REGION REQUIRES LESS STORAGE THAN RASTER AS NUMBER OF GRIDS WILL BE LESS GRIDS COULD BE TRIANGLES, SQUARES OR HEXAGON SQUARES COMMONLY USED BECAUSE ORIENTATION PROBLEM COMES IN FOR OTHER SHAPES

QUAD-TREE STRUCTURE : CRITIQUE-1 B C D BA BC BAC BAD BCA BCB BCC RESULTS IN TREE STRUCTURE (PARENT CHILD RELATION SHIPS AMONGST THE CELLS) FOR STORAGE AND RETRIEVAL

QUAD-TREE STRUCTURE : CRITIQUE-2 B C D BA BC BAC BAD BCA BCB BCC REQUIRES LESS STORAGE THAN RASTER AS NUMBER OF GRIDS WILL BE LESS GRID B WILL BE REPRESENTED BY ONLY 5 CELLS AGAINST 16 IN RASTER MODE

QUAD-TREE STRUCTURE - CRITIQUE-3 B C D BA BC BAC BAD BCA BCB BCC AMENABLE TO VARIABLE SCALE DATABASE HANDLING FACILITATES DISTRIBUTED DATABASE HANDLING OF LARGE DATABASES VARIOUS OTHER QUADTREE APPROCHES

QUAD-TREE STRUCTURE - CRITIQUE-4 VERY SENSITIVE FOR CO-ORDINATE TRANSFORMATION TRANSLATION ROTATION ENTIRE TREE STRUCTURE HAS TO BE RE-WORKED ON AFFECTING THESE TRANSFORMATIONS

QUAD-TREE STRUCTURE - CRITIQUE-5 MANY OTHER APPROCHES PM QUADTREE SUB-DIVISION BASED ON DECOMPSITION OF BOUNDARY EDGES AND VERTICES ORIGINAL VECTOR STRUCTURE AND TOPOLOGY IS MAINTAINED, THUS GIVES BEST OF BOTH WORLD POINT QUADTREE SUB-DIVISION BASED ON LOCATION OF ORDERED DATA POINTS RATHER THAN REGULAR SPATIAL DECOMPOSITION MX , PR, AND MANY MORE...

SPATIAL DATA MODELS - CRITIQUE MODEL AFFECTS ALL ASPECTS OF GIS EFFICIENCY DIFFERENT APPROACHES STRIVE TO REALISE IDEAL REPRESENTATION OF FEATURES IN GIS VIS-A-VIS THE ASPECTS GIVEN IN TABLE NONE OF THE APPROACHES GIVES IDEAL SOLUTION

NON SPATIAL DATA HANDLING IN GIS BASED ON DATABASE MANAGEMENT SYSTEM (DBMS) CONCEPTS

DATABASE MANAGEMENT SYSTEM (DBMS) STRUCTURED/ SYSTEMATIC, SHARABLE, NON-REDUNDANT STORAGE OF DATA DBMS STANDARD S/W TOOL FACILITATING ALL ASPECTS OF DATABASE MANAGEMENT VIZ INPUT, STORAGE, RETRIEVAL & PRENENTATION

PURPOSE OF DBMS APPROACH REDUCED DATA REDUNDANCY - VOLUME, CONSISTENCY, INTEGRITY, QUALITY DATA DICTIONARY - SELF DESCRIPTIVE, DOCUMENTED STORAGE PROGRAM & DATA INDEPENDENCE - INDEPENDANT CHANGE OF USER PROGRAM AND/OR DATA STORAGE FORMAT ( ITEMS, FILES, DEVICE) TRANSPARENCY - USER FREE FROM BOTHERATIONS OF INTERNAL STORAGE INTRICACIES MULTIPLE USER VIEWS STORED DATABASE (INTERNAL VIEW) CONCEPTUAL VIEW DBMS EXTERNAL VIEW- A VIEW- B USER- A USER- B USER- C USER- D

DBMS TYPES (MODELS) - HEIRARCHIAL RIGID VS HORIZONTAL RELATIONS OCCURANCES CAN NOT BE CHANGED COUNTRY STATE REGION CITY TOWN

DBMS MODELS- NETWORK OCCURANCES CAN NOT BE CHANGED COUNTRY STATE REGION CITY TOWN

DBMS MODELS- RELATIONAL COUNTRY STATE REGION CITY TOWN C1 C2 C3 S1 S2 S3 R1 R2 R3 T1 T2 FLEXIBLE RELATIONSHIPS, OCCURANCES REDUNDANCY COUNTRY STATE C1 S1 C2 S2 C3 S3 .. .. STATE CITY S1 C1 S1 C2 S3 C3 .. .. STATE TOWN S3 T1 S3 T2 .. .. REGION CITY .. .. COUNTRY REGION C3 R1 C3 R2 C2 R3 .. .. REGION TOWN ... ... STATE REGION .. ..

GIS-VS-DBMS TWO WAYS TO USE DBMS CONCEPT IN GIS TOTAL DBMS SOLUTION - ALL DATA OPERATIONS IN DBMS ENVIRONMENT PROBLEMS VARIABLE LENGTH OF RECORDS FOR CO-ORDINATES INFINITE NUMBER OF RELATIONSHIPS AMONGST THE SPATIAL OBJECTS INTERNAL STRUCTURE TOO COMPLEX FOR DBMS'S TO PROVIDE TRANSPARENCY MIXED SOLUTION - GEO RELATIONAL SOME DATA ELEMENTS (ATTRIBUTES, ENTITY RELATIONSHIPS) IN DBMS (INFO,DBASE,ORACLE, INFORMIX) SOME DATA (LOCATIONAL) DIRECTLY FROM FILES BECAUSE DIFFICULT TO HANDLE IN DBMS MODEL SECOND METHOD GEO RELATIONAL USED IN GIS

GEO RELATIONAL MODEL IN GIS P1 P2 P3 P4 N1 N2 N3 N4 N5 GEO DATA IN PROPRIETORY FORMAT - HIDDEN FROM USERS NON-SPATIAL DATA IN RELATIONAL (RDBMS) - ACCESSIBLE ARCS ID CO-ORD A1 ............... A2 ............... A3 ............... POLYGONS ID ARCS P1 A1,A2,A3 P2 A2,A7,A5,A6 P3 A3,A5,A4 NODES ID CO-ORD N1 X,Y N2 X,Y N3 X,Y ARCS ID L-POLY R-POLY FNODE TNODE LEN DESCR .. A1 P1 0 N3 N1 ... ..... A2 P1 P2 N2 N3 ... ..... ... .... .... .... .... .... ..... POLYGONS ID AREA PERI DESCR POP .. P1 ... .... ............. ....... P2 .... .... ............. ........

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