[postgis-users] A table of DE-9IE patterns and types of topological relations

[Jim Klassen]

As an aside, I am noticing these graphics probably aren't very 
accessible to people with vision impairments.  There is a lack of 
meaningful alt-text, a general fuzziness/soft edges, and use of several 
colors of similar lightness.  In particular, the red is hard to separate 
out in grayscale and the red is the part that is most important as it is 
describing the part of the image that applies to that grid cell.

I'm not sure if it will come through on the list, but I've converted the 
3x3 grid image from [1] to grayscale below as an example.  I know I'd 
have a very hard time picking out which section was what if I didn't 
already know the answer ahead of time.



[1] https://postgis.net/workshops/postgis-intro/_images/de9im3.jpg

On 4/15/22 15:08, Shaozhong SHI wrote:
> This is very interesting.
>
> However, this needs to be further detailed with a table to explain a 
> variety of cases and uses.
>
> Regards,
>
> David
>
> On Fri, 15 Apr 2022 at 02:48, Paul Ramsey <pramsey at cleverelephant.ca> 
> wrote:
>
>     https://postgis.net/workshops/postgis-intro/de9im.html
>
>     > On Apr 14, 2022, at 4:35 PM, Shaozhong SHI
>     <shishaozhong at gmail.com> wrote:
>     >
>     > The use of ST_Relate appears very attractive.  However, there
>     appears not yet a table detailing DE_9IE patterns and types of
>     topological relations.
>     >
>     > There also appears that not much literature on the use of it for
>     data quality assurance or things like deriving quality data from
>     raw data.
>     >
>     > Can anyone enlighten me?
>     >
>     > Regards,
>     >
>     > David
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