[closed] How to generate tiles in NAD83 projection?

The OSM PostGIS 0.6 schema ("pg_snapshot") is built on the WGS-84 projection, as can be seen by one of the (many) lines of its creation script:

-- Add a postgis point column holding the location of the node.
SELECT AddGeometryColumn('nodes', 'geom', 4326, 'POINT', 2);

To convert them to a new projection (in this case "NAD83", SRID 4269 as listed here), you cannot simply set the SRID of the column:

UPDATE table SET the_column_4326 = ST_SetSRID(the_column_4326, 4326);

Because the ST_SetSRID() function does not perform a projection transformation, as described on the documentation.

Therefore, you have to use the ST_Transform() function, saving the result on another column that has the SRID of the NAD-83 projection. For example:

SELECT AddGeometryColumn('nodes','geom_4269', 4269, 'POINT', 2);
UPDATE nodes SET geom_4269 = ST_Transform(geom, 4269);

And then using the new column as the source of the data, or issuing a few more commands to replace the old column with the new one. Please note that things may get somewhat complicated should the columns be part of indexes, for example.

Make sure that you have the NAD-83 projection installed on your PostGIS spatial_ref_sys table. If not, you can always add it (from the spatialreference.org site (careful with the line breaks):

INSERT into spatial_ref_sys (srid, auth_name, auth_srid, proj4text, srtext) values ( 94269, 'epsg', 4269, '+proj=longlat +ellps=GRS80 +datum=NAD83 +no_defs ', 'GEOGCS["NAD83",DATUM["North_American_Datum_1983",SPHEROID["GRS 1980",6378137,298.257222101,AUTHORITY["EPSG","7019"]],AUTHORITY["EPSG","6269"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.01745329251994328,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4269"]]');

You may also try to perform the transformation "on the fly" changing the source code of your interface, or maybe creating views from the tables, but probably it would be very CPU expensive (and probably very slow as well).

Additional material obtained from this StackOverflow question

EDIT: Fixed some typos, added link to st_transform reference.