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spellinh
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Vince
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I have a column named position with geo data. Query:

SELECT ST_SRID(position) FROM checkpoint LIMIT 1;

returns 4326

If I try to simplify/compress points with

SELECT st_dumppoints(st_simplify(st_makeline(points.position)), 0.005))).geom
FROM 
    (SELECT position
    FROM checkpoint) AS points

it works, but my question is, is st_simplify SRID aware function? Or should I transform the points to another coordinate system with ST_Transform? (The function probably reduces the number of nodes based on line section angles and the simplification may not give the correct results if it does not acknowledge lat lon coordinates - lat : lon ratio is not 1, which is the case with x and y from cartesianCartesian coordinate system).

I have a column named position with geo data. Query:

SELECT ST_SRID(position) FROM checkpoint LIMIT 1;

returns 4326

If I try to simplify/compress points with

SELECT st_dumppoints(st_simplify(st_makeline(points.position)), 0.005))).geom
FROM 
    (SELECT position
    FROM checkpoint) AS points

it works, but my question is, is st_simplify SRID aware function? Or should I transform the points to another coordinate system with ST_Transform? (The function probably reduces the number of nodes based on line section angles and the simplification may not give the correct results if it does not acknowledge lat lon coordinates - lat : lon ratio is not 1, which is the case with x and y from cartesian coordinate system).

I have a column named position with geo data. Query:

SELECT ST_SRID(position) FROM checkpoint LIMIT 1;

returns 4326

If I try to simplify/compress points with

SELECT st_dumppoints(st_simplify(st_makeline(points.position)), 0.005))).geom
FROM 
    (SELECT position
    FROM checkpoint) AS points

it works, but my question is, is st_simplify SRID aware function? Or should I transform the points to another coordinate system with ST_Transform? (The function probably reduces the number of nodes based on line section angles and the simplification may not give the correct results if it does not acknowledge lat lon coordinates - lat : lon ratio is not 1, which is the case with x and y from Cartesian coordinate system).

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miloslu
  • 155
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I have a column named position with geo data. Query:

SELECT ST_SRID(position) FROM checkpoint LIMIT 1;

returns 4326

If I try to simplify/compress points with

SELECT st_dumppoints(st_simplify(st_makeline(points.position)), 0.005))).geom
FROM 
    (SELECT position
    FROM checkpoint) AS points

it works, but my question is, is st_simplify SRID aware function? Or should I transform the points to another coordinate system with ST_Transform? (The function probably reduces the number of nodes based on line section angles and the simplification may not give the correct results if it does not acknowledge lat lon coordinates - lat : lon ratio is not 1, which is the case with x and y from cartesian coordinate system).

I have a column named position with geo data. Query:

SELECT ST_SRID(position) FROM checkpoint LIMIT 1;

returns 4326

If I try to simplify/compress points with

SELECT st_dumppoints(st_simplify(st_makeline(points.position)), 0.005))).geom
FROM 
    (SELECT position
    FROM checkpoint) AS points

it works, but my question is, is st_simplify SRID aware function? Or should I transform the points to another coordinate system with ST_Transform? (The function probably reduces the number of nodes based on line section angles and the simplification may not give the correct results if it does not acknowledge lat lon coordinates - lat : lon ratio is not 1, which is the case with x and y from cartesian coordinate system.

I have a column named position with geo data. Query:

SELECT ST_SRID(position) FROM checkpoint LIMIT 1;

returns 4326

If I try to simplify/compress points with

SELECT st_dumppoints(st_simplify(st_makeline(points.position)), 0.005))).geom
FROM 
    (SELECT position
    FROM checkpoint) AS points

it works, but my question is, is st_simplify SRID aware function? Or should I transform the points to another coordinate system with ST_Transform? (The function probably reduces the number of nodes based on line section angles and the simplification may not give the correct results if it does not acknowledge lat lon coordinates - lat : lon ratio is not 1, which is the case with x and y from cartesian coordinate system).

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miloslu
  • 155
  • 4

SRID awareness in Postgis functions

I have a column named position with geo data. Query:

SELECT ST_SRID(position) FROM checkpoint LIMIT 1;

returns 4326

If I try to simplify/compress points with

SELECT st_dumppoints(st_simplify(st_makeline(points.position)), 0.005))).geom
FROM 
    (SELECT position
    FROM checkpoint) AS points

it works, but my question is, is st_simplify SRID aware function? Or should I transform the points to another coordinate system with ST_Transform? (The function probably reduces the number of nodes based on line section angles and the simplification may not give the correct results if it does not acknowledge lat lon coordinates - lat : lon ratio is not 1, which is the case with x and y from cartesian coordinate system.