# Questions tagged [de-9im]

The Dimensionally Extended nine-Intersection Model (DE-9IM) is a topological model and a standard used to describe the spatial relations of two spatial objects.

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### Why the * and not an F at position (2,1) in the intersection pattern matrix of the Contains predicate

The Contains intersection pattern matrix should be: T*****FF* according to [1], [2] and [3] (but strangely not [4]... for which the matrix is symmetrical, hence Contains==Within, which is not correct ...
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1 vote
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### PostGIS function to get the corresponding intersection matrix pattern for any of the 8 spatial relationships between two geometries

I have a quick and very simple question for which I have not (yet) been able to find an answer: is there a PostGIS function to get the intersection matrix pattern corresponding to any of the 8 ...
• 10.6k
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### What is the pattern matrix equivalent of ST_Equals()?

Within the OGC Simple Feature Access Part 1, I found this: Whereas, in PostGIS (3.4.0dev 3.3.0rc2-335-gae95dd219): SELECT ST_RelateMatch( ST_Relate( 'LINESTRING(1 1, 2 2)', ...
• 10.6k
478 views

### What exactly are the definitions of the boundary and interior of a line or a point?

Regarding the DE-9IM and the OGC spatial predicates for expressing relationships between two geometries; I'm wondering what exactly are the boundary and interior of respectively a line and a point? Is ...
• 10.6k
1 vote
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### Is the boundary of a polygon comprised in its interior?

I'm wondering, regarding the DE-9IM and the OGC spatial predicates for expressing relationships between two geometries; is the boundary of a polygon comprised in its interior or not? If not, does it ...
• 10.6k
1 vote
560 views

### Role of boundaries when using shapely within function

According to the shapely documentation: object.within(other) Returns True if the object’s boundary and interior intersect only with the interior of the other (not its boundary or exterior) ...
• 143
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### ST_RELATE - Intersect ignore shared boundary

Using postgis I am trying to find polygons that intersect, ignoring polygons that only have a shared boundary (edge). ST_Relate(g1, g2, 'T********') is a standard intersection. ST_Relate(g1, g2, 'TF*...
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### postgis st_relate polygon inside another and sharing a boundary

I am trying to select polygons inside an other one WITH a common boundary. It seems that st_relate is the way but I can't find the right matrix, even if I don't see where the fault is in : st_relate(e....
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### How to determine if a Polygon is inside another Polygon's hole

Given two valid polygons P and Q, what's the cheapest / fastest way to determine: If polygon Q is inside one of polygon P's holes (interior rings), or vice versa. (see illustration below) To the ...
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### Boundary of MultiLinestring in DE-9IM

can somebody help me understand (probably giving visual examples) what does this sentence mean which is quoted from the wiki page of nine intersection model: Those points that are in the boundaries ...
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### Using DE-9IM patterns in python plugin for QGIS?

I'd like to compare geometries using DE-9IM patterns in my QGIS plugin written in Python. I've tried to instantiate QgsGeos but it seems there's no such module in qgis.core, as reported by the ...
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### What is the difference between Spatial predicates "Covers" and "Contains"?

I try to understand the Spatial predicates of the DE-9IM Intersection matrix. I don't get the difference between predicates Covers (respective CoveredBy) and Contains (resp. Within). I try to draw ...
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### How does spatial polygon %over% polygon work to when aggregating values in r?

I'm working on an environmental epidemiology project where I have point exposures (~ 2,000 industrial hog operations - IHOs). These IHOs spray on nearby fields, but the feces water droplets and smell ...
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### Regarding spatial relationships, what is the Dimensionally Extended 9 Intersection Model (DE-9IM)? [duplicate]

In plain English what is the Dimensionally Extended nine-Intersection Model (DE-9IM)? What is the meaning of each row/column in the matrix? How can I use that information to build a relation matrix?...
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1 vote
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### Get DE-9IM matrix in spatialite?

Is there a way to get the DE-9IM matrix between two geometries in a Spatialite function, analogous to the st_relate() function in PostGIS? (I find it very helpful to spatially join using intersect() ...
• 202
1 vote
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### What topologic relation means "interior-disjoint"?

I am using the JTS Topology Suite, and trying to write an expression that means "shape A and shape B are interior disjoint". I read this documentation page but I don't entirely understand the ...
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### SQL Server STRelate equivalent of Oracles SDO_RELATE(...mask=anyinteract)

In Oracle Spatial, we are running checks on a graph. The Check should provide Nodes, which are marked as endnodes (Attribute "EDGEDEGREE" equals 1) but are in fact located somewhere along an edge. We ...
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### How do I describe a special relationship between connected edges?

Consider this simple situation where three edges connect at a node: I’d like to write a succinct and clear description of the relationship between A and B in such a way that differentiates it from ...
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