[postgis-users] Non GIS uses of PostGIS: Any tips?

[James Keener]

I believe the 3rd dimension is sometimes used as time (instead of elevation).  Example:

> 5.19. Trajectory Functions Abstract

> These functions support working with trajectories. A trajectory is a linear geometry with a measure (M value) on each coordinate. The measure values must increase along the line. Spatio-temporal data can be modelled by using relative times (such as the epoch) as the measure values.

https://postgis.net/docs/manual-3.1/reference.html

You might be able to use QGIS to help visualize this, though I haven't used it with 3d data, so I can't provide any more concrete guidance on that front.

Jim

On May 23, 2022 2:17:28 AM EDT, Rory Meyer <rory.meyer at VLIZ.be> wrote:
>Afternoon everyone,
>
>I'm assisting a PhD student with their work and I think PostGIS could provide some interesting tools. The problem is that it's using spatial data in a non GIS way.
>
>The student is monitoring the settling behaviour of oyster sprats (larvae) to determine the natural features that lead up to oyster reefs. The experiment is to have a bunch of sprats in a petri dish, simulate a predator or existing oyster reef using chemicals, and to measure the settlement behaviour over several hours using a webcam mounted above the petri-dish. The initial steps would be to use computer vision tools to get an (x,y,t) vector for each oyster sprat, or movement segment, for the duration of the experiment. Using PostGIS functions to build trajectories, calculate average/min/max speed per segment, see if there are any intersections between multiple sprats, possibly map trajectories to behaviours. I'm not sure what else, I'm not a biologist.
>
>My question is how do you do this with a non-spatial SRID? Can I just use pixel locations as X,Y fields, set the SRID to 0 and get pixels/sec out of any ST_funcs? Is there some previous work done on creating a camera specific SRID (probably a bit overkill) to take into account distortions and transform pixel/sec to meter/sec?
>
>Regards,
>Rory

-- 
Sent from my Android device with K-9 Mail. Please excuse my brevity.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/postgis-users/attachments/20220523/4181dd09/attachment.htm>