1. Tony Rees – C-squares Oct 2007 1 Nested Grids: the c-squares global grid Tony Rees CSIRO Marine and Atmospheric Research, Hobart Tony.Rees@csiro.au for: PEMS Workshop on Nested Grids, 21 October 2007 version: final - with update, September 2009

2. Tony Rees – C-squares Oct 2007 2 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!)

3. Tony Rees – C-squares Oct 2007 3 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.

4. Tony Rees – C-squares Oct 2007 4 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 sequence 10º 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 new spatial indexing system and its applicability to the description of oceanographic datasets. Oceanography 16 (1), pp. 11-19.

5. Tony Rees – C-squares Oct 2007 5 WMO 10-degree squares (starting point for c-squares recursive subdivision) 78177816781578147813781278117810780978087807780678057804780378027801780018001801180218031804 1805180618071808180918101811181218131814181518161817 77177716771577147713771277117710770977087707770677057704780377027701770017001701170217031704 1705170617071708170917101711171217131714171517161717 76177616761576147613761276117610760976087607760676057604780376027601760016001601160216031604 1605160616071608160916101611161216131614161516161617 75177516751575147513751275117510750975087507750675057504780375027501750015001501150215031504 1505150615071508150915101511151215131514151515161517 74177416741574147413741274117410740974087407740674057404780374027401740014001401140214031404 1405140614071408140914101411141214131414141514161417 73177316731573147313731273117310730973087307730673057304780373027301730013001301130213031304 1305130613071308130913101311131213131314131513161317 72177216721572147213721272117210720972087207720672057204780372027201720012001201120212031204 1205120612071208120912101211121212131214121512161217 71177116711571147113711271117110710971087107710671057104780371027101710011001101110211031104 1105110611071108110911101111111211131114111511161117 70177016701570147013701270117010700970087007700670057004780370027001700010001001100210031004 1005100610071008100910101011101210131014101510161017 50175016501550145013501250115010500950085007500650055004500350025001500030003001300230033004 3005300630073008300930103011301230133014301530163017 51175116511551145113511251115110510951085107510651055104510351025101510031003101310231033104 3105310631073108310931103111311231133114311531163117 52175216521552145213521252115210520952085207520652055204520352025201520032003201320232033204 3205320632073208320932103211321232133214321532163217 53175316531553145313531253115310530953085307530653055304530353025301530033003301330233033304 3305330633073308330933103311331233133314331533163317 54175416541554145413541254115410540954085407540654055404540354025401540034003401340234033404 3405340634073408340934103411341234133414341534163417 55175516551555145513551255115510550955085507550655055504550355025501550035003501350235033504 3505350635073508350935103511351235133514351535163517 56175616561556145613561256115610560956085607560656055604560356025601560036003601360236033604 3605360636073608360936103611361236133614361536163617 57175716571557145713571257115710570957085707570657055704570357025701570037003701370237033704 3705370637073708370937103711371237133714371537163717 58175816581558145813581258115810580958085807580658055804580358025801580038003801380238033804 3805380638073808380938103811381238133814381538163817 30 ° N 60 ° N 90 ° N 0 ° 30 ° S 60 ° S 90 ° S 180 ° W 150 ° W 120 ° W 90 ° W 60 ° W 30 ° W 0 ° 30 ° E 60 ° E 90 ° E 120 ° E 150 ° E 180 ° E NW (7xxx) NE (1xxx) SE (3xxx) SW (5xxx)

6. Tony Rees – C-squares Oct 2007 6 78177816781578147813781278117810780978087807780678057804780378027801780018001801180218031804 1805180618071808180918101811181218131814181518161817 77177716771577147713771277117710770977087707770677057704780377027701770017001701170217031704 1705170617071708170917101711171217131714171517161717 76177616761576147613761276117610760976087607760676057604780376027601760016001601160216031604 1605160616071608160916101611161216131614161516161617 75177516751575147513751275117510750975087507750675057504780375027501750015001501150215031504 1505150615071508150915101511151215131514151515161517 74177416741574147413741274117410740974087407740674057404780374027401740014001401140214031404 1405140614071408140914101411141214131414141514161417 73177316731573147313731273117310730973087307730673057304780373027301730013001301130213031304 1305130613071308130913101311131213131314131513161317 72177216721572147213721272117210720972087207720672057204780372027201720012001201120212031204 1205120612071208120912101211121212131214121512161217 71177116711571147113711271117110710971087107710671057104780371027101710011001101110211031104 1105110611071108110911101111111211131114111511161117 70177016701570147013701270117010700970087007700670057004780370027001700010001001100210031004 1005100610071008100910101011101210131014101510161017 50175016501550145013501250115010500950085007500650055004500350025001500030003001300230033004 3005300630073008300930103011301230133014301530163017 51175116511551145113511251115110510951085107510651055104510351025101510031003101310231033104 3105310631073108310931103111311231133114311531163117 52175216521552145213521252115210520952085207520652055204520352025201520032003201320232033204 3205320632073208320932103211321232133214321532163217 53175316531553145313531253115310530953085307530653055304530353025301530033003301330233033304 3305330633073308330933103311331233133314331533163317 54175416541554145413541254115410540954085407540654055404540354025401540034003401340234033404 3405340634073408340934103411341234133414341534163417 55175516551555145513551255115510550955085507550655055504550355025501550035003501350235033504 3505350635073508350935103511351235133514351535163517 56175616561556145613561256115610560956085607560656055604560356025601560036003601360236033604 3605360636073608360936103611361236133614361536163617 57175716571557145713571257115710570957085707570657055704570357025701570037003701370237033704 3705370637073708370937103711371237133714371537163717 58175816581558145813581258115810580958085807580658055804580358025801580038003801380238033804 3805380638073808380938103811381238133814381538163817 30 ° N 60 ° N 90 ° N 0 ° 30 ° S 60 ° S 90 ° S 180 ° W 150 ° W 120 ° W 90 ° W 60 ° W 30 ° W 0 ° 30 ° E 60 ° E 90 ° E 120 ° E 150 ° E 180 ° E NW (7xxx) NE (1xxx) SE (3xxx) SW (5xxx) * you are here! WMO 10-degree squares (starting point for c-squares recursive subdivision)

7. Tony Rees – C-squares Oct 2007 7 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)

8. Tony Rees – C-squares Oct 2007 8 10-, 5- degree c-squares in the Australian region 3314

9. Tony Rees – C-squares Oct 2007 9 10-, 5- degree c-squares in the Australian region 3314 12 34

10. Tony Rees – C-squares Oct 2007 10 Recursive subdivision principle (in the SE global quadrant) - for 10 -> 1, 1 -> 0.1, 0.1 -> 0.01 degree squares, etc. 100 110 120 130 140 350 360 370 380 390 101 141 351 391 102 142 352 392 103 143 353 393 104 114 124 134 144 354 364 374 384 394 205 215 225 235 245 455 465 475 485 495 206 246 456 496 207 247 457 497 208 248 458 498 209 219 229 239 249 459 469 479 489 499 1 2 3 4

11. Tony Rees – C-squares Oct 2007 11 3314:100 3314:1 3314 3314:499

12. Tony Rees – C-squares Oct 2007 12 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)

13. Tony Rees – C-squares Oct 2007 13 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??)

14. Tony Rees – C-squares Oct 2007 14 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?

15. Tony Rees – C-squares Oct 2007 15 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)

16. Tony Rees – C-squares Oct 2007 16 Hierarchical spatial search: OBIS example http://www.iobis.org/

17. Tony Rees – C-squares Oct 2007 17 OBIS, USA: Hierarchical spatial search (for species with records in selected area)

18. Tony Rees – C-squares Oct 2007 18 OBIS, USA: Hierarchical spatial search (for species with records in selected area)

19. Tony Rees – C-squares Oct 2007 19 C-squares as spatial metadata: MarLIN example http://www.cmar.csiro.au/marlin/

20. Tony Rees – C-squares Oct 2007 20 C-squares as spatial metadata (list of square IDs = “dataset footprint”)

21. Tony Rees – C-squares Oct 2007 21 C-squares as spatial metadata (list of square IDs = “dataset footprint”)

22. Tony Rees – C-squares Oct 2007 22 C-squares as spatial metadata (list of square IDs = “dataset footprint”)

23. Tony Rees – C-squares Oct 2007 23 C-squares as spatial metadata (list of square IDs = “dataset footprint”)

24. Tony Rees – C-squares Oct 2007 24 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)

25. Tony Rees – C-squares Oct 2007 25 C-squares as grid cell identifiers: AquaMaps example http://www.aquamaps.org/

26. Tony Rees – C-squares Oct 2007 26 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

27. Tony Rees – C-squares Oct 2007 27 (Looks familiar?) (from PEMS presentation, SSC2007)

28. Tony Rees – C-squares Oct 2007 28 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

29. Tony Rees – C-squares Oct 2007 29 C-squares as grid cell identifiers: example from the AquaMaps project 1.0 0.5 0 2829303132 1.0 0.5 0 7891011 1.0 0.5 0 1020304050 1.0 0.5 0 AB Temperature Substrate type Salinity Depth Modelled fish-habitat relationships (SI’s) Temperature SI map Depth SI map Salinity SI map Substrate SI map    HSI = 1/4 Low suitability High suitability UnsuitableMedium Habitat suitability index map Digital environmental maps recoded with the SI’s

30. Tony Rees – C-squares Oct 2007 30 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.

31. Tony Rees – C-squares Oct 2007 31 Variable resolution encoding using c- squares: Satellite Data Index example http://www.marine.csiro.au/remotesensing/csq-chooser.htm

32. Tony Rees – C-squares Oct 2007 32 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.

33. Tony Rees – C-squares Oct 2007 33 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):

34. Tony Rees – C-squares Oct 2007 34

35. Tony Rees – C-squares Oct 2007 35

36. Tony Rees – C-squares Oct 2007 36

37. Tony Rees – C-squares Oct 2007 37 (what just happened here?) fragment of the spatial index… –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)

38. Tony Rees – C-squares Oct 2007 38

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42. Tony Rees – C-squares Oct 2007 42 –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

43. Tony Rees – C-squares Oct 2007 43

44. Tony Rees – C-squares Oct 2007 44 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.)

45. Tony Rees – C-squares Oct 2007 45 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.)

46. Tony Rees – C-squares Oct 2007 46 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.)

47. Tony Rees – C-squares Oct 2007 47 –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.:

48. Tony Rees – C-squares Oct 2007 48 Museum Victoria Bioinformatics search interface (0.5 degree squares, regional)

49. Tony Rees – C-squares Oct 2007 49 AquaMaps, also similar CMAR data (0.5 degree squares, national + global)

50. Tony Rees – C-squares Oct 2007 50 Vertebrate census data, e.g. birds (1 degree squares, national)

51. Tony Rees – C-squares Oct 2007 51 BRS fisheries / associated data (0.5 degree squares, national)

52. Tony Rees – C-squares Oct 2007 52 AFMA data (0.1 degree / 6 minute squares, sub-national)

53. Tony Rees – C-squares Oct 2007 53 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.ppthttp://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 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.ppthttp://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.ppthttp://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/http://www.cmar.csiro.au/csquares/ C-squares on SourceForge: http://csquares.sourceforge.net/.http://csquares.sourceforge.net/

54. Tony Rees – C-squares Oct 2007 54 http://www.cmar.csiro.au/csquares/

55. Tony Rees – C-squares Oct 2007 55 http://www.cmar.csiro.au/csquares/

56. Tony Rees – C-squares Oct 2007 56 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.

57. Tony Rees – C-squares Oct 2007 57 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.