Hi gentlemen, I hope you don't mind me reviving the old thread (it was quite informative, thank you!)
The problem I'm trying to solve here is: how to move X and Y meters (by long and lat, respectively) from a given point? So far I found only the methods related to distance measuring between two geometries, but what about the reverse task?
So far I've been able to come with the following:
1. Buffer the given point with X meters.
2. Intersect it with a horisontal line beginning in the given point and ending somewhere far enough (+-180).
3. Get the endpoint of the resulting intersection line.
4. Repeat steps 1-3 for that endpoint using Y meters buffer and vertical line.
This kinda works, but it obviously does hell of an unneeded extra work.
An alternative might be:
0. Use a local projection that has (0,0) meters point bound to, say, (151, -31) geodegrees.
1. Transform the given point from degrees to meters of that local projection.
2. Calculate the new (+X, +Y) point in meters.
3. Transform the new point back to degrees.
In the second option I could actually do a lot more in the "local" projection and then transform the end result into degrees. Yet the spatial reference mentions the existence of ST_Transform method, but doesn't give any details at all.
Can anyone comment on these points? Did I miss any other solution?
P.S. Here's a third option which I may implement for the lack of anything better:
1. For the given point (x0, y0), find the distance between it and (x0+1, y0) -> gets the linear value of 1 longitude degree in the given locality
2. Do the same for the latitude degree.
3. Use those values as multipliers in local calculations.