7. Other 10 deg. squares in the Australian + NZ region of interest Tony Rees: C-squares nested grid notation
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10. C-squares nested subdivisions (e.g. in SE global quadrant): Tony Rees: C-squares nested grid notation Intermediate quadrant notation (based on absolute values irrespective of positive or negative): 1: low lat, low lon 2: low lat, high lon 3: high lat, low lon 4: high lat, high lon
11. C-squares nested subdivisions (e.g. in SE global quadrant): Tony Rees: C-squares nested grid notation Continuing “Canberra” example , lat. 3 5 S, 14 9 E: 5 deg. square will be 3314:4 1 deg. square will be 3314:4 59 (etc.)
14. C-squares in practice – e.g. in CMAR “MarLIN” metadata system Tony Rees: C-squares nested grid notation
15. C-squares in practice – e.g. in CMAR “MarLIN” metadata system Tony Rees: C-squares nested grid notation
16. C-squares in practice – e.g. in CMAR “MarLIN” metadata system Tony Rees: C-squares nested grid notation adds these elements:
17. C-squares in practice – e.g. in CMAR “MarLIN” metadata system Tony Rees: C-squares nested grid notation adds these elements:
18. C-squares in practice – e.g. in CMAR “MarLIN” metadata system Tony Rees: C-squares nested grid notation adds these elements: … can even Google “3414:371:2” to retrieve this dataset description (plus spatially overlapping ones)
19. Tony Rees: C-squares nested grid notation Sample c-squares enabled systems (as at Sep 2011) AquaMaps marine species modelled distribution OBIS point data records CMAR project survey sites CMAR satellite data footprint
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22. Thank you Tony Rees: C-squares nested grid notation image courtesy Tisham Dhar, CMAR VIZ project Contact Us Phone: 1300 363 400 or +61 3 9545 2176 Email: enquiries@csiro.au Web: www.csiro.au
25. Tony Rees: C-squares nested grid notation Equal area satellite data swath requires more grid squares as it approaches the poles – but system can handle this
codes vary systematically in each quadrant: 1000-1817, 3000-3817, 5000-5817, 7000-7817
uses 1 digit for latitude (N or S), 2 for longitude (W or E)
This approximates to region of interest for CMAR, IMOS etc. – including regional seas and S. Ocean down to Australian Antarctic Territory
Online converters available for points, multi-points, lines and polygons (using pl/sql in this instance) cia the c-squares website, www.cmar.csiro.au/csquares/
C-squares mapper is a simple web utility in existence since 2002, can be called from any web page by embedding a small HTML form and sending relevant c-square codes to be plotted (or could convert to KML or other and plot on Google Earth etc.)
Exposing the codes as searchable text also permits third party indexing – will support spatial searches without realising it.
AquaMaps for ~10,000 marine species since 2005 CMAR Satellite data index (60,000 scenes searchable in <1 sec) constructed 2004 OBIS using c-squares for mapping since 2002, spatial indexing since 2004 CMAR project data – indexed in MarLIN metadata system for almost 10 years (+ ongoing)
Shows why 0.5 deg. squares are a good choice for global mapping – “sweet spot” between resolution (~50km) and storage requirements For Australian use, will be a matter to determine same sweet spot for regional data (plus surrounding seas too)
This visualisation shows 0.01 deg / 1 km squares colour coded for annual fishing catch, draped over a hi-res bathy off the coast of Tasmania
If reprojected e.g. on polar projection, true shape over the ground is revealed