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Nested Grids: the c-squares global grid. Tony Rees CSIRO Marine and Atmospheric Research, Hobart [email protected] for: PEMS Workshop on Nested Grids, 21 October 2007 version: final - with update, September 2009. The Big Challenge:.

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Nested grids the c squares global grid

Nested Grids: the c-squares global grid

Tony Rees

CSIRO Marine and Atmospheric Research, Hobart

[email protected]

for: PEMS Workshop on Nested Grids, 21 October 2007

version: final

- with update, September 2009

Tony Rees – C-squares Oct 2007 1


The big challenge

The Big Challenge:

Integrating distributed and heterogeneous spatial data resources to advance science and societal goals

Opening the “Data Closet”

(With thanks to K. Stocks et al. / SDSC for the image and concept!)

Tony Rees – C-squares Oct 2007 2


One solution rasterised data on a common grid

One solution: rasterised data on a common grid

  • Grids come in different flavours…

    • Geodesic, global “equal area” (e.g. triangular, hexagonal, other)

    • Lat / lon, “equal angle” e.g. 1º x 1º grids, etc. (in unprojected, = “geographic” projection)

    • Local projected “equal area” grids e.g. 100 km grids, etc.

      • Typically regional / national scale, do not integrate globally;do not cope well with longitudinal shifts

      • Areas of interest are sometimes outside the grid (e.g. offshore islands, high seas, etc.)

  • This project (PEMS) has identified a requirement for a large scale “Grid System 1” lat / lon based grid, meshing with local, projected “System 2” grids for finer scale data

  • C-squares is an example global scale, lat / lon based grid that may be of interest for this project’s needs for Grid System 1.

Tony Rees – C-squares Oct 2007 3


The c squares global grid

The c-squares global grid

  • C-squares: acronym for “Concise Spatial Query and Representation System” (or: CSIRO squares ??)

  • Developed at CMAR in 2001-2, published in scientific literature in 2003*

  • Cover entire world surface, not just the sea (despite choice of journal for initial publication)

  • Based on pre-existing, established “WMO square” notation, for global 10º x 10º squares

  • C-squares notation subdivides WMO squares into a nested grid using alternate base 2, base 5 division, giving the sequence10º x 10º > 5º x 5º > 1º x 1º > 0.5º x 0.5º > 0.1º x 0.1º, etc.

    * Rees, Tony. 2003. "C-squares", a newspatial indexing system and its applicabilityto the description of oceanographic datasets.Oceanography 16 (1), pp. 11-19.

Tony Rees – C-squares Oct 2007 4


Wmo 10 degree squares starting point for c squares recursive subdivision

180° W

150° W

120° W

90° W

60° W

30° W

30° E

60° E

90° E

120° E

150° E

180° E

90° N

5117

5017

7517

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7817

5217

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3104

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1104

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3304

3004

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3205

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3405

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1005

1605

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3305

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3206

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1017

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60° N

30° N

30° S

60° S

90° S

WMO 10-degree squares(starting point for c-squares recursive subdivision)

NW

(7xxx)

NE

(1xxx)

SW

(5xxx)

SE

(3xxx)

Tony Rees – C-squares Oct 2007 5


Wmo 10 degree squares starting point for c squares recursive subdivision1

180° W

150° W

120° W

90° W

60° W

30° W

30° E

60° E

90° E

120° E

150° E

180° E

90° N

5817

7817

7317

7717

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5017

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7017

7117

5217

5117

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7709

7609

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7608

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5608

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5108

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7708

7008

5308

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7308

7408

5808

7108

5708

5508

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5007

5707

5207

7307

5107

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7807

5407

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5507

7507

5307

5807

7707

7007

5607

7107

7607

7306

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5406

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5806

7506

5106

5506

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5706

7706

5306

7006

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5206

5606

7406

7205

7305

5205

7805

5805

7605

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5405

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7804

5304

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5404

7604

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5804

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7304

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5104

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7803

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5203

5703

5603

5303

5103

7803

5003

7803

5403

7803

7803

7803

5803

5503

7402

5802

5002

5202

5702

7102

7702

5602

7002

7302

7502

7202

5102

5402

5302

7802

7602

5502

7701

7601

5801

7101

7001

7201

5601

5701

5101

5401

5001

5201

5301

7501

7301

7801

5501

7401

7300

5100

7000

5500

5400

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5700

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7600

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1100

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1200

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3001

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1001

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1201

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1101

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1802

1702

3402

1402

1302

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3002

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1002

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1602

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3302

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1103

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3003

3103

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1803

1203

1303

3203

3803

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3104

3004

1304

1004

1204

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1404

1104

3204

3804

3304

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3404

3704

1704

3604

1804

1105

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1305

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3605

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3105

3805

3305

3405

3205

3005

3705

1005

1705

1205

1306

3806

3406

1606

3206

3606

1006

1406

1806

3306

3706

3006

1206

3106

1106

3506

1506

1706

1007

3007

1507

1607

3207

3307

3807

3107

1307

1707

3707

1207

3607

1107

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1407

3407

1807

1708

3008

1808

1008

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3208

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3108

1408

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3408

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1308

1208

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3308

3808

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3109

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3209

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3309

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1111

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3111

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1511

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1412

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1013

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1113

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3013

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1813

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1213

3213

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3813

3113

1413

3613

1814

1314

1614

3114

1214

3614

1114

1514

1414

3314

3814

3414

1714

3214

1014

3714

3514

3014

3315

3615

1615

1115

3715

3515

3115

1515

1415

1015

3415

1215

3015

1715

1315

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3215

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3716

3116

1616

3616

3816

1316

1816

3016

1016

1116

3416

1516

3516

1216

1416

1716

3316

1017

1617

3617

1117

3417

1217

3517

1517

1317

3117

3717

3317

1717

3817

3017

1817

1417

3217

60° N

30° N

30° S

60° S

90° S

WMO 10-degree squares(starting point for c-squares recursive subdivision)

NW

(7xxx)

NE

(1xxx)

SW

(5xxx)

SE

(3xxx)

* you arehere!

Tony Rees – C-squares Oct 2007 6


The c squares global grid cont d

The c-squares global grid – cont’d

  • Each grid cell identifier (= c-squares code) “knows” the identity of its parent, grandparent, etc.

  • Aggregated search can be done by interrogating only the required leading chars. of the code, e.g.:

    • 10º c-square code (~1000 km):3414 (= WMO square code)

    • 5º c-square code (~500 km):3414:2

    • 1º c-square code (~100 km:3414:227

    • 0.5º c-square code (~50 km):3414:227:3

    • 0.1º c-square code (~10 km):3414:227:383 (etc.)

      (this is the nested set of squares that includes the point at lat -42.82, lon 147.38, in decimal degrees)

    • Search for character string “3414” (ten degree square), with wildcard appended, will return any of these nested data items

    • Same available at other levels of the hierarchy as applicable (i.e., search on any parent code can easily be configured to return all of its children as well, if desired)

Tony Rees – C-squares Oct 2007 7


10 5 degree c squares in the australian region

10-, 5- degree c-squares in the Australian region

3314

Tony Rees – C-squares Oct 2007 8


10 5 degree c squares in the australian region1

10-, 5- degree c-squares in the Australian region

1

2

3314

3

4

Tony Rees – C-squares Oct 2007 9


Nested grids the c squares global grid

100

101

102

103

104

205

206

207

208

209

110

114

215

219

1

2

120

124

225

229

130

134

235

239

140

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142

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144

245

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249

350

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455

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4

3

370

374

475

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390

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498

499

Recursive subdivision principle (in the SE global quadrant)- for 10 -> 1, 1 -> 0.1, 0.1 -> 0.01 degree squares, etc.

Tony Rees – C-squares Oct 2007 10


Nested grids the c squares global grid

3314:1003314:133143314:499

Tony Rees – C-squares Oct 2007 11


Points of interest

Points of interest

  • C-squares notation for 10º squares is identical to that for WMO 10º squares (i.e., no transformation required)

  • 1º and 0.5º squares are popular data aggregation sizes at regional scales

  • 0.5º squares are equivalent to 1:100,000 Australian mapsheets (with global, cf. locally applicable, numbering system)

  • 0.1º squares and finer are useful for data holdings at sub-regional / local scales

  • No direct support for 2.5º, 2º, or 0.25º squares in this system, or degrees / mins / secs notation (except 30 min, = 0.5 degrees)

Tony Rees – C-squares Oct 2007 12


Who uses what google search hits october 2007

Who uses what? (Google search hits – October 2007…)

  • “10 degree squares” OR “ten degree squares”:193

  • “5 degree squares” OR “five degree squares”:563

  • “2.5 degree squares” OR “two point five degree squares”:4

  • “2 degree squares” OR “two degree squares”:135

  • “1 degree squares” OR “one degree squares”:1,660

  • “0.5 degree squares” OR “half degree squares” (30 min):1,060

  • “0.25 degree squares” OR “quarter degree squares” (15 min):17,300 *

  • “10 minute squares” OR “ten minute squares”:249

  • “0.1 degree squares” OR “tenth degree squares” (6 min):575

  • “5 minute squares” OR “five minute squares”:47

  • “3 minute squares” OR “three minute squares”:1

  • “1 minute squares” OR “one minute squares”:51

  • “0.01 degree squares” OR “hundredth degree squares” (0.6 min):1

    * NB: (1) “quarter degree squares” are a common standard in use in Africa for wildlife surveys, which accounts for many / most of these hits

    (2) Of the above, c-squares directly supports the resolutions shown in bold + underline, indirectly could support others (by aggregation / approximate matching??)

Tony Rees – C-squares Oct 2007 13


D m s vs decimal degrees

D/M/S vs. decimal degrees…

  • What fine scale grids (e.g. sub 1-degree) are in use locally / internationally – e.g.:

    • 30 minute = 0.5 degree (~50 km)

    • 5 minute = 0.0833 degree (~10 km)

    • 1 minute = 0.0167 degree (~2 km)

    • 30 second = 0.00833 degree (~1 km)

    • 9 second = 0.0025 degree (~250m)

    • 2 second = 0.00055 degree (~50m)

    • 1 second = 0.000278 degree (~25m)

  • Is there a requirement / preference to maintain similar (deg / min / sec) resolutions in the selected system? (cf. c-squares is based on decimal degrees and half steps)

  • Does this preclude (or encourage) the use of c-squares for resolutions e.g. 0.5 degrees and above?

Tony Rees – C-squares Oct 2007 14


Use cases for c squares of possible interest to this project

Use cases for c-squares, of possible interest to this project

  • Hierarchical spatial search

    • Example shown: OBIS (Ocean Biogeographic information System), USA

  • C-squares as spatial metadata, and associated spatial search (also: mapping)

    • Example shown: MarLIN (Marine Laboratories Information Network), CSIRO, Australia

  • C-squares as grid cell identifiers, for data storage, rapid access, and mapping of outputs

    • Example shown: AquaMaps project (Germany + Philippines)

  • Variable resolution encoding within the same dataset (or data item)

    • Example shown: CSIRO (CMAR) satellite data index

  • Using c-squares for Antarctic / Southern Ocean / Polar data

    • Examples shown: CMAR satellite data index; online polygon fill algorithm (on c-squares website)

Tony Rees – C-squares Oct 2007 15


Nested grids the c squares global grid

Hierarchical spatial search: OBIS example

http://www.iobis.org/

Tony Rees – C-squares Oct 2007 16


Nested grids the c squares global grid

OBIS, USA: Hierarchical spatial search (for species with records in selected area)

Tony Rees – C-squares Oct 2007 17


Nested grids the c squares global grid

OBIS, USA: Hierarchical spatial search (for species with records in selected area)

Tony Rees – C-squares Oct 2007 18


Nested grids the c squares global grid

C-squares as spatial metadata: MarLIN example

http://www.cmar.csiro.au/marlin/

Tony Rees – C-squares Oct 2007 19


Nested grids the c squares global grid

C-squares as spatial metadata (list of square IDs = “dataset footprint”)

Tony Rees – C-squares Oct 2007 20


Nested grids the c squares global grid

C-squares as spatial metadata (list of square IDs = “dataset footprint”)

Tony Rees – C-squares Oct 2007 21


Nested grids the c squares global grid

C-squares as spatial metadata (list of square IDs = “dataset footprint”)

Tony Rees – C-squares Oct 2007 22


Nested grids the c squares global grid

C-squares as spatial metadata (list of square IDs = “dataset footprint”)

Tony Rees – C-squares Oct 2007 23


Nested grids the c squares global grid

C-squares as spatial metadata (list of square IDs = “dataset footprint”)

(A)

(B)

…search for matching square (=tile) ID (A) is much more precise than search by bounding box using “overlapping rectangles” test (B)[far fewer false positives] – presuming tile size is well matched to the data and / or intended query scale (may be an optimization issue here)

Tony Rees – C-squares Oct 2007 24


Nested grids the c squares global grid

C-squares as grid cell identifiers: AquaMaps example

http://www.aquamaps.org/

Tony Rees – C-squares Oct 2007 25


Nested grids the c squares global grid

C-squares as grid cell identifiers: example from the AquaMaps project

“Half degree cell authority file” (HCAF) – covers the world in 259,200 database rows

Tony Rees – C-squares Oct 2007 26


Nested grids the c squares global grid

(Looks familiar?)

(from PEMS presentation, SSC2007)

Tony Rees – C-squares Oct 2007 27


Nested grids the c squares global grid

C-squares as grid cell identifiers: example from the AquaMaps project

“Half degree cell authority file” (HCAF) – covers the world in 259,200 database rows

Tony Rees – C-squares Oct 2007 28


Nested grids the c squares global grid

Modelled fish-habitat relationships (SI’s)

Digital environmental maps recoded with the SI’s

1.0

Temperature

Habitat suitability index map

0.5

Depth

Unsuitable

Medium

0

Low suitability

High suitability

7

8

9

10

11

Salinity

Substrate type

1.0

0.5

0

10

20

30

40

50

1.0

0.5

0

28

29

30

31

32

1.0

0.5

0

A

B

1/4

Temperature SI map

´

Depth SI map

HSI =

´

Salinity SI map

´

Substrate SI map

C-squares as grid cell identifiers: example from the AquaMaps project

Tony Rees – C-squares Oct 2007 29


Nested grids the c squares global grid

C-squares as grid cell identifiers: example from the AquaMaps project

Sample map output (produced by the c-squares mapper)

NB with multiple maps, can then query individual cells for species richness, etc. etc.

Tony Rees – C-squares Oct 2007 30


Nested grids the c squares global grid

Variable resolution encoding using c-squares: Satellite Data Index example

http://www.marine.csiro.au/remotesensing/csq-chooser.htm

Tony Rees – C-squares Oct 2007 31


Variable resolution encoding example from the cmar satellite data index

Variable resolution encoding: example from the CMAR satellite data index

Special notation available, e.g.3414= ten degree square only (data may be anywhere within it);3414:***:*= all of the 0.5 degree squares within ten degree square 3414.

Tony Rees – C-squares Oct 2007 32


Antarctic data special case or not

Antarctic data – special case or not?

  • AAD, satellite imagery, oceanographic data – much data from region between Australia and Antarctica, as well as on landmass itself and adjacent waters

  • Definite integration benefits if on a common grid / spatial query interface, e.g. OBIS example, others… (no fixed boundary in the ocean / natural world)

  • C-squares covers polar regions as well as rest of world (just have to decide which square to allocate actual pole to!) – uses more squares, but otherwise no intrinsic problem

  • Example from CMAR satellite data index (uses 0.5 degree squares):

Tony Rees – C-squares Oct 2007 33


Nested grids the c squares global grid

Tony Rees – C-squares Oct 2007 34


Nested grids the c squares global grid

Tony Rees – C-squares Oct 2007 35


Nested grids the c squares global grid

Tony Rees – C-squares Oct 2007 36


What just happened here

(what just happened here?)

  • We clicked on square with bounds(lat) -65 – -70, (lon) 130 – 135 … = c-square 3613:3 (user never sees this, but system generates it for the search)

  • System searches for unique scenes with prefix “3613:3” in the spatial index, does a join on other table[s] to satisfy any other criteria

  • Generates list of 473 matching targets in (in this case) <2 seconds

  • Spatial partitioning used in this system, to optimise search and index rebuild speeds (single table split into 100 smaller ones); “duplicate” single large one retained to quickly retrieve all squares associated with a particular scene (for mapping)

fragment of the spatial index…

Tony Rees – C-squares Oct 2007 37


Nested grids the c squares global grid

Tony Rees – C-squares Oct 2007 38


Nested grids the c squares global grid

Tony Rees – C-squares Oct 2007 39


Nested grids the c squares global grid

Tony Rees – C-squares Oct 2007 40


Nested grids the c squares global grid

Tony Rees – C-squares Oct 2007 41


Nested grids the c squares global grid

  • Polygons encoded to c-squares can include a pole without problem: e.g. on-line polygon-fill algorithm on c-squares web site:

    http://www.cmar.csiro.au/csquares/converter.htm

Tony Rees – C-squares Oct 2007 42


Nested grids the c squares global grid

Tony Rees – C-squares Oct 2007 43


Nested grids the c squares global grid

Successful filled polygon conversion

c-square code:

3606:104|3606:114|3606:124|3606:134|3606:143|3606:144|3606:2**|3606:353|3606:354|3606:363|3606:364|3606:372|3606:373|3606:374|3606:382|3606:383|3606:384|3606:391|3606:392|3606:393|3606:394|3606:4**|3607:1**|3607:205|3607:215|3607:225|3607:235|3607:245|3607:246|3607:3**|3607:455|3607:456|3607:465|3607:466|3607:475|3607:476|3607:477|3607:485|3607:486|3607:487|3607:495|3607:496|3607:497|3607:498|3705:239|3705:248|3705:249|3705:384|3705:392|3705:393|3705:394|3705:457|3705:458|3705:459|3705:466|3705:467|3705:468|3705:469|3705:475|3705:476|3705:477|3705:478|3705:479|3705:485|3705:486|3705:487|3705:488|3705:489|3705:495|3705:496|3705:497|3705:498|3705:499|3706:101|3706:102|3706:103|3706:104|3706:110|3706:111|3706:112|3706:113|3706:114|3706:120|3706:121|3706:122|3706:123|3706:124|3706:130|3706:131|3706:132|3706:133|3706:134|3706:140|3706:141|3706:142|3706:143|3706:144|3706:2**|3706:3**|3706:4**|3707:1**|3707:205|3707:206|3707:207|3707:208|3707:215|3707:216|3707:217|3707:218|3707:219|3707:225|3707:226|3707:227|3707:228|3707:229|3707:235|3707:236|3707:237|3707:238|3707:239|3707:245|3707:246|3707:247|3707:248|3707:249|3707:3**|3707:4**| (etc.)

Tony Rees – C-squares Oct 2007 44


Nested grids the c squares global grid

Successful filled polygon conversion

c-square code:

3606:104|3606:114|3606:124|3606:134|3606:143|3606:144|3606:2**|3606:353|3606:354|3606:363|3606:364|3606:372|3606:373|3606:374|3606:382|3606:383|3606:384|3606:391|3606:392|3606:393|3606:394|3606:4**|3607:1**|3607:205|3607:215|3607:225|3607:235|3607:245|3607:246|3607:3**|3607:455|3607:456|3607:465|3607:466|3607:475|3607:476|3607:477|3607:485|3607:486|3607:487|3607:495|3607:496|3607:497|3607:498|3705:239|3705:248|3705:249|3705:384|3705:392|3705:393|3705:394|3705:457|3705:458|3705:459|3705:466|3705:467|3705:468|3705:469|3705:475|3705:476|3705:477|3705:478|3705:479|3705:485|3705:486|3705:487|3705:488|3705:489|3705:495|3705:496|3705:497|3705:498|3705:499|3706:101|3706:102|3706:103|3706:104|3706:110|3706:111|3706:112|3706:113|3706:114|3706:120|3706:121|3706:122|3706:123|3706:124|3706:130|3706:131|3706:132|3706:133|3706:134|3706:140|3706:141|3706:142|3706:143|3706:144|3706:2**|3706:3**|3706:4**|3707:1**|3707:205|3707:206|3707:207|3707:208|3707:215|3707:216|3707:217|3707:218|3707:219|3707:225|3707:226|3707:227|3707:228|3707:229|3707:235|3707:236|3707:237|3707:238|3707:239|3707:245|3707:246|3707:247|3707:248|3707:249|3707:3**|3707:4**| (etc.)

Tony Rees – C-squares Oct 2007 45


Nested grids the c squares global grid

Successful filled polygon conversion

c-square code:

3606:104|3606:114|3606:124|3606:134|3606:143|3606:144|3606:2**|3606:353|3606:354|3606:363|3606:364|3606:372|3606:373|3606:374|3606:382|3606:383|3606:384|3606:391|3606:392|3606:393|3606:394|3606:4**|3607:1**|3607:205|3607:215|3607:225|3607:235|3607:245|3607:246|3607:3**|3607:455|3607:456|3607:465|3607:466|3607:475|3607:476|3607:477|3607:485|3607:486|3607:487|3607:495|3607:496|3607:497|3607:498|3705:239|3705:248|3705:249|3705:384|3705:392|3705:393|3705:394|3705:457|3705:458|3705:459|3705:466|3705:467|3705:468|3705:469|3705:475|3705:476|3705:477|3705:478|3705:479|3705:485|3705:486|3705:487|3705:488|3705:489|3705:495|3705:496|3705:497|3705:498|3705:499|3706:101|3706:102|3706:103|3706:104|3706:110|3706:111|3706:112|3706:113|3706:114|3706:120|3706:121|3706:122|3706:123|3706:124|3706:130|3706:131|3706:132|3706:133|3706:134|3706:140|3706:141|3706:142|3706:143|3706:144|3706:2**|3706:3**|3706:4**|3707:1**|3707:205|3707:206|3707:207|3707:208|3707:215|3707:216|3707:217|3707:218|3707:219|3707:225|3707:226|3707:227|3707:228|3707:229|3707:235|3707:236|3707:237|3707:238|3707:239|3707:245|3707:246|3707:247|3707:248|3707:249|3707:3**|3707:4**| (etc.)

Tony Rees – C-squares Oct 2007 46


Nested grids the c squares global grid

  • Note, (1) C-squares (and the polygon fill algorithm) copes with the polar case with no intrinsic problem

  • (2) automatic, multi-resolution data compression incorporated into the encoding algorithms on the c-squares web site (can be disabled if desired)

  • (3) relevant decompression stage incorporated into the c-squares mapper, also can be disabled as required (e.g. for demo purposes i.e. these slides)

    …Of course, can do much of this (in principle) with any type of grid structure / nomenclature for grid cells, however, c-squares compatible datasets are in general use at sub-national, national, and international scale, e.g.:

Tony Rees – C-squares Oct 2007 47


Nested grids the c squares global grid

Museum Victoria Bioinformatics search interface (0.5 degree squares, regional)

Tony Rees – C-squares Oct 2007 48


Nested grids the c squares global grid

AquaMaps, also similar CMAR data (0.5 degree squares, national + global)

Tony Rees – C-squares Oct 2007 49


Nested grids the c squares global grid

Vertebrate census data, e.g. birds (1 degree squares, national)

Tony Rees – C-squares Oct 2007 50


Nested grids the c squares global grid

BRS fisheries / associated data (0.5 degree squares, national)

Tony Rees – C-squares Oct 2007 51


Nested grids the c squares global grid

AFMA data (0.1 degree / 6 minute squares, sub-national)

Tony Rees – C-squares Oct 2007 52


Selected bibliography reference materials

Selected bibliography / reference materials

Rees, T. 2002. C-squares – a new method for representing, querying, displaying and exchanging dataset spatial extents. Abstract and presentation at EOGEO Technical Workshop, May 2002, accessible via http://www.cmar.csiro.au/csquares/eogeo2002-rees.ppt

Rees, T. 2003. "C-squares", a new spatial indexing system and its applicability to the description of oceanographic datasets. Oceanography 16 (1), 11-19.

Rees, T. 2004. Use of c-squares spatial indexing and mapping in the 2004 release of OBIS, the Ocean Biogeographic Information System. Abstract and presentation at EOGEO Technical Workshop, July 2004, accessible via http://www.cmar.csiro.au/csquares/eogeo04-rees.ppt

Rees, T. and Smith, G. 2004. Application of c-squares spatial indexing to an archive of remotely sensed data. Abstract and presentation at EOGEO Technical Workshop, July 2004, accessible via http://www.cmar.csiro.au/csquares/eogeo04-reessmith.ppt

Kaschner, K., J. S. Ready, E. Agbayani, J. Rius, K. Kesner-Reyes, P. D. Eastwood, A. B. South, S. O. Kullander, T. Rees, C. H. Close, R. Watson, D. Pauly, and R. Froese. 2007. AquaMaps. Abstract and presentation at Ocean Biodiversity Informatics 2007, accessible via http://www.cmar.csiro.au/datacentre/presentations/OBI-2007-Kaschner.ppt

C-squares resources on the web:

  • C-squares home page: http://www.cmar.csiro.au/csquares/

  • C-squares on SourceForge: http://csquares.sourceforge.net/ .

Tony Rees – C-squares Oct 2007 53


Http www cmar csiro au csquares

http://www.cmar.csiro.au/csquares/

Tony Rees – C-squares Oct 2007 54


Http www cmar csiro au csquares1

http://www.cmar.csiro.au/csquares/

Tony Rees – C-squares Oct 2007 55


Update september 2009

Update September 2009

  • (1) C-squares functionality is currently being added to the IMOS (and AODCJF/BlueNet) Metadata Search and Entry Tool – MEST

    • IMOS MEST is part of the GeoNetwork Open Source Development Community (origin with FAO in Italy) – currently installed base in >20 countries worldwide; Australian developments will be fed back into the GeoNetwork trunk for anyone to use

  • (2) IHO (International Hydrographic Office) is considering a recommendation from their technical committee to use c-squares for spatial indexing of hydrographic charts from all nations; proposal made at Montreal, May 2009, to be progressed at Sydney, October 2009

  • (3) C-squares is still providing backbone of all the spatial searches and mapping for OBIS (USA); 3 attempts to introduce more sophisticated GIS front ends have so far failed to deliver desired outcomes, c-squares is still mission critical for them…

  • (4) AquaMaps – another bulk c-squares user – is engaged with Google Oceans to provide prototype “what lives here” functionality on mouseover/click, for waters anywhere in the world.

Tony Rees – C-squares Oct 2007 56


Conclusions

Conclusions

  • C-squares may be a good fit with PEMS data store needs for “Grid System 1” (but may need to think further about finer scale, D/M/S grid requirements)

  • System has global coverage / interoperability, has been real-world tested for 5+ years, Antarctic / polar data not a problem (or features crossing the date line)

  • Some supporting infrastructure already in place, e.g.:

    • Tools i.e. encoders (lat/lon to c-squares), decoders, validators

    • C-squares mappers (x 4 worldwide at present time)

      … possibly useful starting point for further development to suit project needs

  • Supports efficient, variable-resolution (quadtree-like) encoding for large regions if required, no impact on search performance (actually, it gets faster!)

  • Database, platform, & vendor independent system; transparent & simple / rapid operation (no “black boxes”); open source repository for code, suits multi-developer model

  • Potential for ongoing interaction with local development “team” at CMAR as needed.

Tony Rees – C-squares Oct 2007 57


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