Problems with Simple Feature and solution using Postgis Topology

1. Postgis Topology will replace Postgis SimpleFeature
Lars Aksel Opsahl (NIBIO)
The Norwegian
Institute of
Bioeconomy
Research

2. Postgis
Simple Feature
Postgis Topology
Sandro Santilli

3. 9/1/16 3Postgis Topology will replace Postgis SimpleFeature
Why use different projection on server and client ?
SRID 25832
(UTM 32, meter
5-12 degrees )
SRID 25833
(UTM 33, meter
12-21 degrees)
SRID 25835
(UTM 35, meter
21-30)
SRID 4258
(degrees)

4. 9/1/16 4Postgis Topology will replace Postgis SimpleFeature
Client
Srid 25833 (meter)
Simple Feature
Postgis database
Srid 4258 (degrees)
Test case
Simple feature
(polygons, lines,points)
Simple feature
(polygons, lines,points)

5. 9/1/16 5Postgis Topology will replace Postgis SimpleFeature
0% drifted points, 0% overlap
(postgis binary to postgis binary(WKB) and back with no projection)
SRID 25833

6. 9/1/16 6Postgis Topology will replace Postgis SimpleFeature
90% drifted points
(meter to degrees and back using binary)
400 km.

7. 9/1/16 7Postgis Topology will replace Postgis SimpleFeature
90% drifted points
(meter to degrees and back using binary)
400 km.

8. 9/1/16 8Postgis Topology will replace Postgis SimpleFeature
99% of polygons overlaps
(meter to degrees and back using binary)
400 km.

9. 9/1/16 9Postgis Topology will replace Postgis SimpleFeature
99% of polygons overlaps
(meter to degrees and back using binary, with 100 reputations )
400 km.

10. 9/1/16 10Postgis Topology will replace Postgis SimpleFeature
Points drifts with many kilometers
(Projection formula UTM 35 on data in UTM 32
meter to degrees and back using binary, with 100 reputations)
50 km.

11. 9/1/16 11Postgis Topology will replace Postgis SimpleFeature
What about JSON
JSON

12. 9/1/16 12Postgis Topology will replace Postgis SimpleFeature
99% drifted points
(postgis binary to JSON and back)
400 km.

13. 9/1/16 13Postgis Topology will replace Postgis SimpleFeature
100% of polygons overlap
(postgis binary to JSON and back)
400 km.

14. 9/1/16 14Postgis Topology will replace Postgis SimpleFeature
Nano meter and TopologyExceptions
10 m.

15. 9/1/16 15Postgis Topology will replace Postgis SimpleFeature
Nano meter and TopologyExceptions
10 m.

16. 9/1/16 16Postgis Topology will replace Postgis SimpleFeature
TopologyException: side location conflict at 10.056395207707636 …....
10 m.

17. 9/1/16 17Postgis Topology will replace Postgis SimpleFeature
TopologyException: side location conflict at 10.056395207707636 …....
10 m.

18. 9/1/16 18Postgis Topology will replace Postgis SimpleFeature
Move border with Simple Feature

19. 9/1/16 19Postgis Topology will replace Postgis SimpleFeature
Move border with SimpleFeature

20. SIMPLE FEATURE CAUSES
“Drifting points”
“Duplication of common borders”
(Tiny overlaps means more Topo Errors)

21. 9/1/16 21Postgis Topology will replace Postgis SimpleFeature

22. 9/1/16 22Postgis Topology will replace Postgis SimpleFeature
Only send points changed by user back to server.

23. 9/1/16 23Postgis Topology will replace Postgis SimpleFeature
Only send points changed by user back to server.

24. 9/1/16 24Postgis Topology will replace Postgis SimpleFeature
Duplication of common borders

25. 9/1/16 25Postgis Topology will replace Postgis SimpleFeature
Move border with Postgis Topology

26. 9/1/16 26Postgis Topology will replace Postgis SimpleFeature
How to extend a polygon

27. 9/1/16 27Postgis Topology will replace Postgis SimpleFeature
Client
github.com/
NibioOpenSource/pgtopo_update_sql
Postgis Topology
Only new lines/points
Using generic JSON API
I
TopoJSON
JSON

28. 9/1/16 28Postgis Topology will replace Postgis SimpleFeature
Postgis Topology also gives a lot more than this
No drifting points No duplications

29. 9/1/16 29Postgis Topology will replace Postgis SimpleFeature
Draw a line
around
all polygons
in a layer

30. 9/1/16 30Postgis Topology will replace Postgis SimpleFeature
Postgis Topology:5 new points
Simple Feature: 333105 new points
(333100 duplicates)

31. 9/1/16 31Postgis Topology will replace Postgis SimpleFeature
{"type":"Topology","objects":{"collection":
{"type":"GeometryCollection","geometries":
[{"type":"Polygon","properties":{"id":520},"arcs":[[-1]]}]}},"arcs":
[[[9717,419],[-1126,-419],[-5070,958],[-2113,898],[-1126,2036],
[422,2335],[-704,2754],[1972,1018],[2253,0],[1267,-419],[1409,-
1437],[3098,-6467],[-282,-1257]]],"transform":{"scale":
[0.007100710071007101,0.016701670167016704],"translate":
[1088433,7800262]}}
● GeoJSON 7.6 MB
● TopoJSON 1.3 MB
● 80 % reduction
What is TopoJSON ?

32. 9/1/16 32Postgis Topology will replace Postgis SimpleFeature
ST_Simplify and Simple Feature Using Topology
common border will not match. No problem

33. 9/1/16 33Postgis Topology will replace Postgis SimpleFeature
Reduced update bandwidth needs for client
Client
Server
Payload reduced
by ST_Simplify

34. 9/1/16 34Postgis Topology will replace Postgis SimpleFeature
ST_Simplify works perfect with Postgis Topology
7990316 bytes 149400 byte (98 % less)

35. 9/1/16 35Postgis Topology will replace Postgis SimpleFeature
JSON mean API flexibility

36. 9/1/16 36Postgis Topology will replace Postgis SimpleFeature
Reduced update bandwidth needs for client
Client
Server
Only new
new data

37. 9/1/16 37Postgis Topology will replace Postgis SimpleFeature
Standard SQL means more open ness

38. 9/1/16 38Postgis Topology will replace Postgis SimpleFeature
Row level seucirty

39. 9/1/16 39Postgis Topology will replace Postgis SimpleFeature
Row level seucirty

40. 9/1/16 40Postgis Topology will replace Postgis SimpleFeature
Client rendering D3 and TopoJSON

41. “GeoServer and MapServer
supports Simple Feature”
“Postgis Topology supports casting
to Simple Feature”

42. Postgis Topology
- tested with one billion points
http://www.slideshare.net/laopsahl/foss4-g-topologyjuly162015
- seems to be solid and few errors

43. Why is not Postgis Topology
used by everybody yet ?

44. 9/1/16 44Postgis Topology will replace Postgis SimpleFeature
Software comes and goes.
Mind the data.
Arnulf Christl

45. Thanks for your attention.
Lars Aksel Opsahl developer at
The Norwegian Institute of
Bioeconomy Research (NIBIO)