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POFinding path length along points in postgis
 

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  1. POFinding path length along points in postgis
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    <p>I have a postgis database (postgres 8.4.11, postgis 1.5.2) with gps-observations where I would like to calculate some travel distances. </p> <p>I calculate the travelled distance from one point to another one hour later with select observedid,ST_Distance(p1.shape_utm,p2.shape_utm) from gpspoint p1, gpspoint p2 where p2.datetime=p1.datetime+interval '1 hour'</p> <p>(and of course a bit more, but this is the distance part in it) I have defined this as a view so that I can easily do a select * from movement_view where observedid=42</p> <p>Question 1: Is it possible to make the view so that I can define the time interval as well? </p> <p>e.g. select * form movement_view where observedid=42 and interval='15 minutes' ?</p> <p>Question 2: Is it possible in SQL/postgis to calculate the total distance travelled for a period of time? I have a gpspoint each 5th second and would like to calculate travelled distance for e.g. 1 hour following each gps-point. I can calculate the travelled distance for each point using the same method as above, and then I may be able to use the sum() function, but how?</p> <p>Table definition: id integer,<br> gpsstatus character(2),<br> datetime timestamp without time zone,<br> lat numeric(9,6),<br> lon numeric(9,6),<br> alt numeric(9,4),<br> time integer,<br> datafileid integer,<br> shape geometry,<br> speed double precision,<br> dist double precision,<br> shape_utm geometry,<br> lokalitet character(128),<br> cowid integer </p> <p>Id: Primary key There are indexes on datetime,lokalitet,cowid,gpsstatus, gist-index on shape and shape_utm. </p>
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    1. USMortenSickel
    1. USMortenSickel
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    1. COSorry, slightly wron title, a better one would have been "finding length of path along points in postgis"
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      1. USMortenSickel
    2. CObah, tried to remove the comment after I discovered that I could edit the title, but too late...
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    3. COanswer is yes to both, it's relatively easy to create a subquery that has key, distance between two points for each set of points and then sum those results. I added a postgresql tag as your answer is more sql then it is geo...more views this way. If you give table schema info, you'll probably get a working answer.
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      1. USTwelfth
 

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