[gdal-dev] how to pick the correct projection

[Mark Johnson]

It seem that EPSG has reserved the numbers
- 32600-32799 for basic WGS 84 / UTM zones

For these basic WGS 84 / UTM zone *
- Northern Hemisphere: add 32600 to the Zone Number
- Southern Hemisphere: add 32700 to the Zone Number

On a Spatialite Database, the following Query will list the basic UTM-Zones

SELECT
 srid,
 auth_name,
 auth_srid,
 ref_sys_name,
 proj4text,
 srtext
FROM
 spatial_ref_sys
WHERE
( -- Northern Hemisphere
 (proj4text = '+proj=utm +zone='||(srid-32600)||' +datum=WGS84 +units=m
+no_defs') OR
  -- Southern Hemisphere
 (proj4text = '+proj=utm +zone='||(srid-32700)||' +south +datum=WGS84
+units=m +no_defs')
)
ORDER BY proj4text;
-- 120 results

---
There are other Projections that also use UTM (non-basic)
- to list these:

SELECT
 srid,
 auth_name,
 auth_srid,
 ref_sys_name,
 proj4text,
 srtext
FROM
 spatial_ref_sys
WHERE
( -- Other Projections that use UTM
 (srid NOT BETWEEN 32600 AND 32799) AND
 (
  (proj4text LIKE '+proj=utm +zone%')
 )
)
ORDER BY proj4text;
-- 947 results

Mark Johnson

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