[postgis-users] Get point certain degree of another point

[tommy408]

Thank you Marc and Mike



Mike Toews wrote:
> 
> On 2010-01-22 19:05, tommy408 wrote:
>> How can I get a point at a certain distance and degree from another
>> point.
>> For example 10 meter distance to another point at 45 degrees.
>>    
> 
> You could also use some simple trigonometry with ST_Translate().
> 
> For example, consider 'geom' at (100 100), and a point 12 units away 30 
> degrees from the x-axis (math style with CCW direction .. or a 
> geographic bearing of 60 degrees CW from North).
> 
> SELECT AsEWKT(ST_Translate(geom, cos(rad)*dist, sin(rad)*dist))
> FROM (select ST_MakePoint(100, 100) as geom, 12 as dist, 30*2*pi()/360 
> as rad) AS foo;
> 
> POINT(110.392304845413 106)
> 
> Or your example from (0 0) using a math-style angle:
> 
> SELECT AsEWKT(ST_Translate(geom, cos(rad)*dist, sin(rad)*dist))
> FROM (select ST_MakePoint(0, 0) as geom, 10 as dist, 45*2*pi()/360 as 
> rad) AS foo;
> 
> POINT(7.07106781186548 7.07106781186547)
> 
> This could easily be turned into a PL/pgSQL function if you require it 
> frequently. Also, be aware of the geographic versus mathematics 
> definition of angles, since they have opposite rotations and start 90 
> degrees from each other.
> 
> -Mike
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> 
> 

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