In SQL Server 2014, I have a database with Geometry points - City
Driving from City A to City B gives me a line (we take an airplane).
I need to find points in my database - which are in certain distance (10 miles) "off-track" of this line.
I know how to find the closest points around a single point, how to calculate the distance between them - but - how can I search along this line? Like POI in your Navi...
DECLARE #g geography
SELECT #g = Geo_LatLong_deg
FROM airports
WHERE iata_code = 'MyAirportCode' -- radius 100km
SELECT *
FROM airports
WHERE #g.STDistance(Geo_LatLong_deg) <= 100000
Use the STBuffer method. Assuming that you've got some way to determine your path as a geography instance, it's as simple as:
declare #distance float = 16.09344 --10 miles in km
select *
from airports
where #path.STBuffer(#distance).STIntersects(Geo_LatLong_deg) = 1
By way of explanation, the STBuffer() method creates a region that is the set of points within 10 miles of your path. Then, we select all points from your table that intersect with that region with STIntersects().
Thank you for your help. I mixed up Long/Lat sequence in string... now I get the results as expected.
here the code - if others want to see how to combine two or more points - together with the area around the line(s).
DECLARE #BuildString NVARCHAR(MAX)
SELECT #BuildString = COALESCE(#BuildString + ',', '') + CAST(longitude_deg AS NVARCHAR(50)) + ' ' + CAST(latitude_deg AS NVARCHAR(50))
FROM dbo.airports where iata_code='RLG' or iata_code='FRA'
ORDER BY ID
SET #BuildString = 'LINESTRING(' + #BuildString + ')';
DECLARE #LineFromPoints geography = geography::STLineFromText(#BuildString, 4326);
declare #distance float = 50000
select *
from airports
where #LineFromPoints.STBuffer(#distance).STIntersects(airports.GEO_LatLong_deg) = 1 and type<>'heliport'
Related
I have string coordinates in my table but I want to do some geographical functionalities, So I need first to convert this string value to geography.like this:
geography::STGeomFromText('POINT([location])', 4326).MakeValid().STDistance(#p)
but for sure this code didn't work as it needs here point not string coordinates.
The full code:
geography::STGeomFromText('POINT([location])', 4326).MakeValid().STDistance(#p);
DECLARE #p geography;
SET #p = geography::STGeomFromText('POINT({$Lon} {$Lat})', 4326);
Select TOP 1 id, location from branches where {$location} <= {$this->radius} order by {$location}
It's a little difficult to provide a perfect solution without seeing how the code is interporlating the variables, but SQL could be having issues recognizing your long/lat as strings with the STGeomFromText method.
Could you try something like this:
SELECT geography::STGeomFromText('POINT(' + CAST([$Long] AS VARCHAR(20)) + ' ' + CAST([$Lat] AS VARCHAR(20)) + ')', 4326)
Or more succinctly:
SELECT geography::Point([$Lat], [$Long], 4326)
I'm new to SQL Server. I'm trying to figure out how I can get the below one done:
I have thousands of lat/long positions pointing to the same OR very close by locations. It's all stored flat in a SQL Server table as LAT & LONG columns.
Now to cluster the lat/longs and pick one representation per cluster, what I must be doing?
I read through a method called "STCentroid" :
https://msdn.microsoft.com/en-us/library/bb933847.aspx
But is it worth letting the Server do a polygon with all these million rows and find the center point? Which would implicitly mean a single representation for all the near by duplicates. Might be an in efficient/wrong way?
Only points around few meters must be considered as duplicate entries.
I'm thinking how I can pick the right representation.
In better words:
If there's a group of points G1{} (GPS positions) trying to point to a location L1. (Physical loc). & There's a group of points G2{}, trying to point to a location L2. How do I derive Center Point CP1 from G1{}. & CP2 from G2{}, such that CP1 is very close to L1 & CP2 is very close to L2.
And the fact is, L1 & L2 could be very near to each other say, 10 feet.
Just thinking how do I approach this problem. Any help please?
Clustering points will be problematic. You are going to have issues if you have two potential clusters close together, and if you need precision or optimization, then you will need to do some research on your implementation. Try: Wiki-Cluster Analysis
However, if the points clusers are fairly far apart, then you could try a fairly simple cluster and then find the envelopes.
Something like this may work, although you would be well served to actually make a spatial column and add a spatial index.
ALTER TABLE Recordset ADD (ClusterID INT) -- Add a grouping ID
GO
DECLARE #i INT --Group Counter
DECLARE #g GEOGRAPHY --Point from which the cluster will be made
DECLARE #Limit INT --Distance limitation
SET #Limit = 10
SET #i = 0
WHILE (SELECT COUNT(*) FROM Recordset R WHERE ClusterID IS NULL) > 0 --Loop until all points are clustered
BEGIN
SET #g = (SELECT TOP 1 GEOGRAPHY::STPointFromText('POINT(' + CAST(LAT AS VARCHAR(20)) + ' ' + CAST(LONG AS VARCHAR(20)) + ')', 4326) WHERE ClusterID IS NULL) --Point to cluster on
UPDATE Recordset SET ClusterID = #i WHERE GEOGRAPHY::STPointFromText('POINT(' + CAST(LAT AS VARCHAR(20)) + ' ' + CAST(LONG AS VARCHAR(20)) + ')', 4326).STDistance(#g) < #Limit AND ClusterID IS NULL--update all points within the limit circle
SET #i = #i + 1
END
SELECT --Clustered centers
ClusterID,
GEOGRAPHY::ConvexHullAggregate(GEOGRAPHY::STPointFromText('POINT(' + CAST(LAT AS VARCHAR(20)) + ' ' + CAST(LONG AS VARCHAR(20)) + ')', 4326)).EnvelopeCenter().Lat AS 'LatCenter',
GEOGRAPHY::ConvexHullAggregate(GEOGRAPHY::STPointFromText('POINT(' + CAST(LAT AS VARCHAR(20)) + ' ' + CAST(LONG AS VARCHAR(20)) + ')', 4326)).EnvelopeCenter().Long AS 'LatCenter',
FROM
RecordSet
GROUP BY
ClusterID
I have geography field of irregular shapes. Geography field can vary from hundred to thousands of Lat/Long points that define that shape. In regards to size it could be from several US. Postal Codes to a size of entire US State. In order to have increased performance I have build Spacial index on that field. On frequent basis I have to find vehicles based on Lat/Long point that are within specific zone.
My original approach was this.
WITH LastP
AS ( SELECT vlp.ID
,GEOGRAPHY::STPointFromText('POINT(' + CAST(vlp.Long AS VARCHAR(20)) + ' '
+ CAST(vlp.Lat AS VARCHAR(20)) + ')', 4326) AS LastKnownPoint
FROM LastPosition AS vlp )
SELECT lp.ID
,zn.ZONE
FROM dbo.GeogZone AS zn WITH ( NOLOCK )
JOIN #zones AS z
ON zn.Zone = z.Zone
JOIN LastP AS lp
ON lp.LastKnownPoint.STWithin(zn.ZoneGeog) = 1
I was getting all records from my table LastPosition and than I converted Lat/Long into Geography point and later JOIN using STWithin function. This process works great but can be very slow. I have tried to adjust Spacial indexes but it did not make big changed.
To increase performance I want to introduce the following process.
From Geography type I will extract NorthLat, SouthLat, EastLong, WestLong
Now I can limit the number of results before I do compare in the following matter.
WITH LastP
AS ( SELECT vlp.ID
,GEOGRAPHY::STPointFromText('POINT(' + CAST(vlp.Long AS VARCHAR(20)) + ' '
+ CAST(vlp.Lat AS VARCHAR(20)) + ')', 4326) AS LastKnownPoint
FROM LastPosition AS vlp
WHERE (vlp.Long BETWEEN #WestLong and #EastLong) AND (vlp.Lat BETWEEN #SouthLat AND #NorthLat))
SELECT lp.ID
,zn.ZONE
FROM dbo.GeogZone AS zn
JOIN #zones AS z
ON zn.Zone = z.Zone
JOIN LastP AS lp
ON lp.LastKnownPoint.STWithin(zn.ZoneGeog) = 1
Here is the code for building the box.
DECLARE #geomenvelope GEOMETRY;
DECLARE #BoundingBox AS TABLE
(
SouthLat DECIMAL(10, 8)
,NorthLat DECIMAL(10, 8)
,EastLong DECIMAL(10, 8)
,WestLong DECIMAL(10, 8)
);
SELECT #geomenvelope = GEOMETRY::STGeomFromWKB(zn.ZoneGeog.STAsBinary(), zn.ZoneGeog.STSrid).STEnvelope()
FROM dbo.GeogZone AS zn
WHERE zn.Zone = 'CA-1'
INSERT INTO #BoundingBox (SouthLat,NorthLat,EastLong,WestLong)
SELECT #geomenvelope.STPointN(1).STY
,#geomenvelope.STPointN(3).STY
,#geomenvelope.STPointN(1).STX
,#geomenvelope.STPointN(3).STX
SELECT *
FROM #BoundingBox
My question: Is there an alternative (easier) way to get East, West, North, South Points from my Geography Field?
Sorry for the late reply, but hope I can add something.
Firstly, the conversion into LastKnownPoint, you should be able to declare it as follows:
GEOGRAPHY::Point(vlp.Lat, vlp.Long, 4326) AS LastKnownPoint
It works just the same, but is so must easier to read and doesn't require the casts.
To get better performance, you wouldn't have to do the conversion if you can store the Lat / Long as a Geography column in itself which if you're searching regularly is a lot of overhead. Doing this would also allow you to use the Zone directly as a filter and using a spatial index and I couldn't recommend it highly enough. Not to mention no longer needing to create the bounding box.
If you can't do all of that, at least the reduction in CAST'ing and Concatenation should gain you a fair few milliseconds here and there.
I am fluent in SQL but new to using the SQL Geometry features. I have what is probably a very basic problem to solve, but I haven't found any good resources online that explain how to use geometry objects. (Technet is a lousy way to learn new things...)
I have a collection of 2d points on a Cartesian plane, and I am trying to find all points that are within a collection of radii.
I created and populated a table using syntax like:
Update [Things] set [Location] = geometry::Point(#X, #Y, 0)
(#X,#Y are just the x and y values, 0 is an arbitrary number shared by all objects that allows set filtering if I understand correctly)
Here is where I go off the rails...Do I try to construct some sort of polygon collection and query using that, or is there some simple way of checking for intersection of multiple radii without building a bunch of circular polygons?
Addendum: If nobody has the answer to the multiple radii question, what is the single radius solution?
UPDATE
Here are some examples I have worked up, using an imaginary star database where stars are stored on a x-y grid as points:
Selects all points in a box:
DECLARE #polygon geometry = geometry::STGeomFromText('POLYGON(('
+ CAST(#MinX AS VARCHAR(10)) + ' ' + CAST(#MinY AS VARCHAR(10)) + ','
+ CAST(#MaxX AS VARCHAR(10)) + ' ' + CAST(#MinY AS VARCHAR(10)) + ', '
+ CAST(#MaxX AS VARCHAR(10)) + ' ' + CAST(#MaxY AS VARCHAR(10)) + ','
+ CAST(#MinX AS VARCHAR(10)) + ' ' + CAST(#MaxY AS VARCHAR(10)) + ','
+ CAST(#MinX AS VARCHAR(10)) + ' ' + CAST(#MinY AS VARCHAR(10)) + '))', 0);
SELECT [Star].[Name] AS [StarName],
[Star].[StarTypeId] AS [StarTypeId],
FROM [Star]
WHERE #polygon.STContains([Star].[Location]) = 1
using this as a pattern, you can do all sorts of interesting things, such as
defining multiple polygons:
WHERE #polygon1.STContains([Star].[Location]) = 1
OR #polygon2.STContains([Star].[Location]) = 1
OR #polygon3.STContains([Star].[Location]) = 1
Or checking distance:
WHERE [Star].[Location].STDistance(#polygon1) < #SomeDistance
Sample insert statement
INSERT [Star]
(
[Name],
[StarTypeId],
[Location],
)
VALUES
(
#Name,
#StarTypeId,
GEOMETRY::Point(#LocationX, #LocationY, 0),
)
This is an incredibly late answer, but perhaps I can shed some light on a solution. The "set" number you refer to is a Spatial Reference Indentifier or SRID. For lat/long calculations you should consider setting this to 4326, which will ensure metres are used as a unit of measurement. You should also consider switching to SqlGeography rather than SqlGeometry, but we'll continue with SqlGeometry for now. To bulk set the SRID, you can update your table as follows:
UPDATE [YourTable] SET [SpatialColumn] = GEOMETRY.STPointFromText([SpatialColumn].STAsText(), 4326);
For a single radius, you need to create a radii as a spatial object. For example:
DECLARE #radiusInMeters FLOAT = 1000; -- Set to a number in meters
DECLARE #radius GEOMETRY = GEOMETRY::Point(#x, #y, 4326).STBuffer(#radiusInMeters);
STBuffer() takes the spatial point and creates a circle (now a Polygon type) from it. You can then query your data set as follows:
SELECT * FROM [YourTable] WHERE [SpatialColumn].STIntersects(#radius);
The above will now use any Spatial Index you have created on the [SpatialColumn] in its query plan.
There is also a simpler option which will work (and still use a spatial index). The STDistance method allows you to do the following:
DECLARE #radius GEOMETRY = GEOMETRY::Point(#x, #y, 4326);
DECLARE #distance FLOAT = 1000; -- A distance in metres
SELECT * FROM [YourTable] WHERE [SpatialColumn].STDistance(#radius) <= #distance;
Lastly, working with a collection of radii. You have a few options. The first is to run the above for each radii in turn, but I would consider the following to do it as one:
DECLARE #radiiCollection TABLE
(
[RadiusInMetres] FLOAT,
[Radius] GEOMETRY
)
INSERT INTO #radiiCollection ([RadiusInMetres], [Radius]) VALUES (1000, GEOMETRY::Point(#xValue, #yValue, 4326).STBuffer(1000));
-- Repeat for other radii
SELECT
X.[Id],
MIN(R.[RadiusInMetres]) AS [WithinRadiusDistance]
FROM
[YourTable] X
JOIN
#radiiCollection RC ON RC.[Radius].STIntersects(X.[SpatialColumn])
GROUP BY
X.[IdColumn],
R.[RadiusInMetres]
DROP TABLE #radiiCollection;
The final above has not been tested, but I'm 99% sure it's just about there with a small amount of tweaking being a possibility. The ideal of taking the min radius distance in the select is that if the multiple radii stem from a single location, if a point is within the first radius, it will naturally be within all of the others. You'll therefore duplicate the record, but by grouping and then selecting the min, you get only one (and the closest).
Hope it helps, albeit 4 weeks after you asked the question. Sorry I didn't see it sooner, if only there was only one spatial tag for questions!!!!
Sure, this is possible. The individual where clause should be something like:
DIM #Center AS Location
-- Initialize the location here, you probably know better how to do that than I.
Dim #Radius AS Decimal(10, 2)
SELECT * from pointTable WHERE sqrt(square(#Center.STX-Location.STX)+square(#Center.STX-Location.STX)) > #Radius
You can then pile a bunch of radii and xy points into a table variable that looks like like:
Dim #MyCircleTable AS Table(Geometry Circle)
INSERT INTO #MyCircleTable (.........)
Note: I have not put this through a compiler, but this is the bare bones of a working solution.
Other option looks to be here:
http://technet.microsoft.com/en-us/library/bb933904.aspx
And there's a demo of seemingly working syntax here:
http://social.msdn.microsoft.com/Forums/sqlserver/en-US/6e1d7af4-ecc2-4d82-b069-f2517c3276c2/slow-spatial-predicates-stcontains-stintersects-stwithin-?forum=sqlspatial
The second post implies the syntax:
SELECT Distinct pointTable.* from pointTable pt, circletable crcs
WHERE crcs.geom.STContains(b.Location) = 1
I have created a table containing US zipcodes along with the latitude and longitude of these zip codes. From the latitude and longitude I created a geography column. I created a spatial index on that geography column. I want to return the closest 100 zip codes to a latitude and longitude so I created the following stored procedure
CREATE PROCEDURE [dbo].[Geo_Locate]
#Latitude DECIMAL,
#Longitude DECIMAL
AS
BEGIN
SET NOCOUNT ON;
DECLARE #GeogTemp NVARCHAR(200)
DECLARE #Geog GEOGRAPHY
-- Create a geography type variable from the passed in latitude and longitude. This will be used to find the closest point in the database
SET #GeogTemp = 'POINT(' + convert(NVARCHAR(100), #Longitude) + ' ' + convert(NVARCHAR(100), #Latitude) + ')'
SET #Geog = geography::STGeomFromText(#GeogTemp, 4326)
-- Run the main query
SELECT TOP 100
[Id],
[Country],
[ZipPostalCode],
[City],
[County],
[Latitude],
[Longitude],
[GeographyCol],
GeographyCol.STDistance(#Geog) AS Distance
FROM
[dbo].[ZipCode] WITH(INDEX(ZipCode_SpatialIndex))
WHERE
GeographyCol.STDistance(#Geog) < 100000 -- 100 KM
ORDER BY
GeographyCol.STDistance(#Geog) ASC
END
However when I pass the latitude = 35.48330 and longitude = -97.17340 to this stored procedure I get the following returned at item 55
869531 US 73045 Harrah Oklahoma OK 35.48330 -97.17340 0xE6100000010C12143FC6DCBD4140174850FC184B58C0 55894.2236191955
The last column is the distance. Basically the query is saying that this record is nearly 56KM from the entered point but the latitude and longitude are the same.
I've read MSDN and my query looks correct. Can anyone help me please?
This one was a doozy and I'm not sure I got it. I started with trying to replicate in purest terms what you were seeing: incorrect STDistance() between two geography points.
DECLARE #zipcode geography
DECLARE #searchpoint geography
SET #zipcode = geography::STPointFromText('POINT(-97.17340 35.48330)', 4326);
SET #searchpoint = geography::STPointFromText('POINT(-97.17340 35.48330)', 4326);
SELECT #zipcode.STDistance(#searchpoint)
The results is, correctly, 0 meters (SRID 4326 uses meters as the distance unit), so I kept scratching my head. The only thing I noticed that I can't replicate is this: you flipped between geography and geometry (your code from question):
SET #Geog = geography::STGeomFromText(#GeogTemp, 4326)
When I plopped that into my code I still got 0 for distance. So my only question, and perhaps you could post the T-SQL, is about your spatial index. I think the STDistance() calculation is going to use the index. So without seeing the index and knowing that you hopped between Geography and Geometry at least in this instance, I'd wonder if the odd results are in there since I can't replicate it with my above code.