[postgis-users] ST_Intersection does not preserve M value

Martin Davis mtnclimb at gmail.com
Mon May 6 14:53:25 PDT 2019


Not exactly the same thing - I believe that ticket is referring to just the
WKB format handling?

I can make a ticket for measure handling by the overlay operations if there
isn't one already.

On Mon, May 6, 2019 at 11:31 AM Darafei "Komяpa" Praliaskouski <
me at komzpa.net> wrote:

> It's in backlog for 6 years already I believe:
> https://trac.osgeo.org/geos/ticket/466
>
> пн, 6 мая 2019, 19:33 карыстальнік Martin Davis <mtnclimb at gmail.com>
> напісаў:
>
>> It should be possible to post-process GEOS results to re-populate the M
>> values if present.  Linear interpolation could be used to estimate values
>> at intra-segment points.  We can put this on the list for future
>> development.
>>
>> On Mon, May 6, 2019 at 4:48 AM Darafei "Komяpa" Praliaskouski <
>> me at komzpa.net> wrote:
>>
>>> Hi,
>>>
>>> GEOS operations do not preserve M, but sometimes preserve Z. You can try
>>> ST_SwapOrdinates(ST_Intersection(ST_SwapOrdinates(geom, 'zm'),...), 'zm').
>>>
>>> On Thu, May 2, 2019 at 5:19 AM Bo Guo <bo.guo at gisticinc.com> wrote:
>>>
>>>> Hi there,
>>>>
>>>> I was trying to cut a portion of the LRS route with an area using
>>>> ST_Intersection.  However the resulting route no longer carries measure
>>>> value.  The behavior is the same for version 9.6 or the latest version
>>>> 11.  Anyone has any suggestions?
>>>>
>>>> Thanks!
>>>>
>>>> Bo
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>>>
>>>
>>>
>>> --
>>> Darafei Praliaskouski
>>> Support me: http://patreon.com/komzpa
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>>
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