[postgis-users] Simple Line Density

[Rémi Cura]

Maybe you should tweak your postgres conf file ,
default conf is very savy
http://www.postgresql.org/docs/9.3/static/runtime-config.html

Cheers,
Rémi-C




2013/11/27 Karl Zinglersen <karl.zinglersen at gmail.com>

> Hi,
> I am dealing with the same types of data and issues as Jeff.
> My procedure for data clean up is:
> 1) CSV files into PostGIS as points
> 1.1) ST_TRANSFORM to projected spatial reference (here EPSG:32621 / UTM
> zone 21 N WGS84)
> 2) ST_MAKELINE to "sub"-lines via PARTITION BY
> 3) Create a gridded polygon layer in same srid
> 4) Run equivalent to select cell_id, line_id from cells, lines where
> intersects(lines.geom, cells.geom
> - but my postgis runs out of memory after a while. And I am sorry to say
> Spatial Analyst doesn't.
> Is there more memory cheap way to do it in PostGIS (e.g. via the raster
> functions - although I haven't found i yet).
>
> Karl
>
> Den onsdag den 26. december 2012 09.58.43 UTC-3 skrev Jeff Adams - NOAA
> Affiliate:
>>
>> Hi Brent,
>>
>> Thanks for the response. I don't think your original response made it
>> into my inbox via the list, but now I see it on the website thread. That
>> seems like it might be a viable alternative, I just worry about those
>> vessel tracks that would be clearly outside of a particular grid cell, but
>> whose buffer would bleed over. How did you handle this type of situation?
>>
>> Jeff
>>
>> On Mon, Dec 24, 2012 at 7:22 PM, <pcr... at pcreso.com> wrote:
>>
>>> Jeff,
>>>
>>> Did you see my reply using vessel tracklines as vectors & a grid in
>>> Postgis to do exactly what you describe?
>>>
>>> Given we were looking at benthic impact, we buffered the tracklines to
>>> create polygons representing the swept area of the deployed fishing gear.
>>> These were clipped by the cells, & we could generate statistics suca as the
>>> cumulative swept area of all tracks with each cell, number of times each
>>> cell was crossed, & given the tracklines have a timestamp associated with
>>> them, we could also look at the temporal pattern of tracks crossing cells,
>>> for things like seasonal impacts & variation between seasons.
>>>
>>> Cheers,
>>>
>>>   Brent Wood
>>>
>>
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