[postgis-devel] 2.5D TIN Operations

[Paul Ramsey]

Well Olivier cadged the idea of a TIN type from a SQL/MM discussion paper I think, which never went anywhere. I don’t know if it had any ST_Functions elabourated in it for analysis (almost certainly: not) but it might provide some language around the edges.

P

> On Mar 27, 2019, at 10:55 AM, Darafei Komяpa Praliaskouski <me at komzpa.net> wrote:
> 
> As a datapoint, a TIN on top of all the roads in Belarus is around 600MB, which fits into Postgres tuple. A city-wide one is below a hundred megabytes, which I believe fits into memory.
> 
> ST_Something was my thought too, but question I have in mind is more about naming: are there names for these operations already, is there a wider list of them somewhere?
> 
> 
> 
> ср, 27 мар. 2019 г. в 20:47, Paul Ramsey <pramsey at cleverelephant.ca <mailto:pramsey at cleverelephant.ca>>:
> Question that comes to mind: how big are these TINs of which you speak?
> 
> I mean, we have a TIN object now, but as with POLYGON and LINESTRING, the expectation is that the TIN fits in-memory. Which means the API is pretty simple, no? Just ST_Something(TIN) returns POLYGON. ST_Union(TIN, TIN) returns TIN? I mean, write out your list of functions, and what they do, I cannot imagine they’ll be too terrible. It only gets terrible when we need to model something larger than memory (ala topology)
> 
> P
> 
> 
>> On Mar 27, 2019, at 10:02 AM, Darafei Komяpa Praliaskouski <me at komzpa.net <mailto:me at komzpa.net>> wrote:
>> 
> 
>> Let's imagine I have a bunch 2.5D TINs representing some measurement - say, a travel time to a central point. I want to perform operations on top of these:
>> 
>>  - for each TIN in the group I would like to get a 2D polygon of bounds where it is the lowest in the group - "here is delivery area for this office" if you wish;
>> 
>>  - combine two TINs into a new one defining a lowest part of surface - "here is our delivery time map".
>> 
>> I understand the maths of this, but how an API for that can look like? Any examples to look at?
>> 
>> 
>> -- 
>> Darafei Praliaskouski
>> Support me: http://patreon.com/komzpa <http://patreon.com/komzpa>
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