Question

I’m using SQL Server 2012, geography.STContains (documentation) and I don’t get why the code below fails.

If I switch to geometry it works.

Can someone explain?

//Daniel

declare @geo geography
set @geo = geography::STPolyFromText('POLYGON ((17.519133203852 59.8297423369731, 17.5190071588812 59.8296936773323, 17.5189979955459 59.8298203729009, 17.5191345140461 59.8298223425544, 17.519133203852 59.8297423369731))', 4326)

-- Is not within
declare @p1 geography
set @p1 = geography::STPointFromText('POINT(17.5184709839477 59.829925754067)', 4326)

-- Is within
declare @p2 geography
set @p2 = geography::STPointFromText('POINT(17.519060 59.829774)', 4326) 

select
    @geo.STContains(@p1), -- should be 0 is 1
    @geo.STContains(@p2) -- should be 1 is 0

UPDATED:
If I invert them it works just fine, but then I don’t get this:

declare @geo geography
set @geo = geography::STPolyFromText('POLYGON ((17.519133203852 59.8297423369731, 17.5190071588812 59.8296936773323, 17.5189979955459 59.8298203729009, 17.5191345140461 59.8298223425544, 17.519133203852 59.8297423369731))', 4326)

select
    @geo.STAsText() Polygon,
    @geo.STPointN(1).STAsText() Point1,
    @geo.STPointN(1).Lat Point1Latitud,
    @geo.STPointN(1).Long Point1Longitude

Which results in this:

Polygon 
POLYGON ((17.519133203852 59.8297423369731, 17.5190071588812 59.8296936773323, 17.5189979955459 59.8298203729009, 17.5191345140461 59.8298223425544, 17.519133203852 59.8297423369731))

Point1  
POINT (17.519133203852 59.8297423369731)

Point1Latitud   
59,8297423369731

Point1Longitude
17,519133203852

Answer 1

Now I found the issue. The user drew the polygon starting lower-right and went clockwise. If I reorder the points from biggest latitude and then go counterwise by sorting on long, lat it works. Found a helper for it, but that only works if you “know it’s wrong”:

if(sqlGeography.EnvelopeAngle() > 90)
    sqlGeography ? sqlGeography.ReorientObject();

Just put together a small solution that will fix my values: https://github.com/danielwertheim/GeographyFactory

and a blogpost about it: http://danielwertheim.se/sqlgeography-in-sql-server-2012-polygon-must-start-on-correct-position/

and a follow up about the real “issue”, the left-hand rule:

http://danielwertheim.se/sqlgeography-in-sql-server-2012-polygon-must-start-on-correct-position-no/