PostGIS - Route matching solution - postgresql
We are building an application where I am a driver and i travel from point A to point B.On my way i can find passengers who travel in the same route.
We are using PostgreSQL with PostGIS extension.
After googling a lot i have found out that we can use linestring to achieve this.I am not fully sure whether this approach will work out.
Suppose I have co-ordinates of my source and destination.
var RouteCoordinates = [
{lat: 37.772, lng: -122.214},
{lat: 21.291, lng: -157.821},
{lat: -18.142, lng: 178.431},
{lat: -27.467, lng: 153.027}
];
I need to store this as linestring in my DB.
After stroring if a passenger is also going in this route but as we know his source and destination wont be exactly in my line string but they will be near.
For example around 1km radius
As you can see my source and destination is that line. And as I am travelling I want to pick all those whose (source and destination) are near to my routes (within particular radius)
If I want to find particular location in my DB within particular radius I will be querying like this
SELECT id, name, address, geom
FROM Seattle_Starbucks
WHERE ST_DWithin(geom, ST_MakePoint(-122.325959,47.625138)::geography, 1000);
Now I can achieve my solution as I am new to postGIS its little bit confusing
How to store all all my source and destination point in DB
ANS: I need to convert in to linestring using this function ST_MakeLine and then store, right?
How to query that based on my requirement as I have mentioned above
Can you please give me the insight on how to achieve this. Your help is greatly appreciated. Thanks
A few thougths on your question:
I need to convert in to linestring using this function ST_MakeLine and
then store, right?
Yes, to merge multiple points into a LINESTRING you can use ST_MakeLine:
SELECT ST_AsText(
ST_MakeLine(ARRAY[ST_MakePoint(-122.21,37.77),
ST_MakePoint(-157.82,21.29),
ST_MakePoint(178.43,-18.14),
ST_MakePoint(153.02,-27.46)]));
st_astext
---------------------------------------------------------------------
LINESTRING(-122.21 37.77,-157.82 21.29,178.43 -18.14,153.02 -27.46)
(1 Zeile)
How to query that based on my requirement as I have mentioned above
Create a buffer on each point of your LINESTRING and check wether other geometries are inside of it.
First, you have to split your rout LINESTRING into POINTs using ST_DumpPoints ...
db=# SELECT ST_AsText((ST_DumpPoints('LINESTRING(-122.21 37.77,-157.82 21.29,178.43 -18.14,153.02 -27.46)'::GEOMETRY)).geom);
st_astext
----------------------
POINT(-122.21 37.77)
POINT(-157.82 21.29)
POINT(178.43 -18.14)
POINT(153.02 -27.46)
(4 Zeilen)
.. and then use ST_Buffer to create a buffer around each point. ST_Buffer returns a geometry with the area surrounding your point (or any other geometry type). For instance, taking the first point of your route (if I didn't switch x and y, it's somewhere in San Francisco) POINT(-122.21 37.76):
db=# SELECT ST_AsText(
ST_Buffer('POINT(-122.21 37.76)'::GEOMETRY,0.0001, 'quad_segs=16'));
Returns this geometry:
POLYGON((-122.2099 37.76,-122.209900481527 37.759990198286,-122.209901921472 37.7599804909678,-122.209904305966 37.7599709715323,-122.209907612047 37.7599617316568,-122.209911807874 37.7599528603263,-122.209916853039 37.7599444429767,-122.209922698955 37.7599365606716,-122.209929289322 37.7599292893219,-122.209936560672 37.7599226989547,-122.209944442977 37.7599168530388,-122.209952860326 37.7599118078736,-122.209961731657 37.7599076120467,-122.209970971532 37.7599043059664,-122.209980490968 37.759901921472,-122.209990198286 37.7599004815273,-122.21 37.7599,-122.210009801714 37.7599004815273,-122.210019509032 37.759901921472,-122.210029028468 37.7599043059664,-122.210038268343 37.7599076120467,-122.210047139674 37.7599118078736,-122.210055557023 37.7599168530388,-122.210063439328 37.7599226989547,-122.210070710678 37.7599292893219,-122.210077301045 37.7599365606716,-122.210083146961 37.7599444429767,-122.210088192126 37.7599528603263,-122.210092387953 37.7599617316568,-122.210095694034 37.7599709715323,-122.210098078528 37.7599804909678,-122.210099518473 37.759990198286,-122.2101 37.76,-122.210099518473 37.760009801714,-122.210098078528 37.7600195090322,-122.210095694034 37.7600290284677,-122.210092387953 37.7600382683432,-122.210088192126 37.7600471396737,-122.210083146961 37.7600555570233,-122.210077301045 37.7600634393284,-122.210070710678 37.7600707106781,-122.210063439328 37.7600773010453,-122.210055557023 37.7600831469612,-122.210047139674 37.7600881921264,-122.210038268343 37.7600923879533,-122.210029028468 37.7600956940336,-122.210019509032 37.760098078528,-122.210009801714 37.7600995184727,-122.21 37.7601,-122.209990198286 37.7600995184727,-122.209980490968 37.760098078528,-122.209970971532 37.7600956940336,-122.209961731657 37.7600923879533,-122.209952860326 37.7600881921264,-122.209944442977 37.7600831469612,-122.209936560672 37.7600773010453,-122.209929289322 37.7600707106781,-122.209922698955 37.7600634393284,-122.209916853039 37.7600555570233,-122.209911807874 37.7600471396737,-122.209907612047 37.7600382683432,-122.209904305966 37.7600290284677,-122.209901921472 37.7600195090322,-122.209900481527 37.760009801714,-122.2099 37.76))
If you're wondering about the shape of this buffer, please read this answer.
And using this query you can check if another geometry is inside of this buffer (ST_Within):
db=# SELECT
ST_Within('POINT(-122.21 37.76)'::GEOMETRY,
ST_Buffer('POINT(-122.21 37.76)'::GEOMETRY,0.0001, 'quad_segs=16'));
st_within
-----------
t
(1 Zeile)
To put it all together, you can use a CTE (aka WITH clause) and write something like this:
WITH j AS (
SELECT
(ST_DumpPoints('LINESTRING(-122.21 37.77,-157.82 21.29,178.43 -18.14,153.02 -27.46)'::GEOMETRY)).geom AS g)
SELECT id, name, address, geom
FROM Seattle_Starbucks
WHERE ST_Within(geom,ST_Buffer(j.g,0.0001, 'quad_segs=16'))
Related
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[out:csv ("name")][timeout:2500];
{{geocodeArea:Roma}}->.searchArea;
(
way["highway"]["name"](area.searchArea);
);
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out;
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(poly:"latitude_1 longitude_1 latitude_2 longitude_2 latitude_3 longitude_3 …");
I'm just not sure where it would go in the query. I tried a few times but I was receiving errors or just blank results. Hopefully if I see an example I should be able to carry out my task effectively.
After doing some research I found the answer. This would give me a list of road names:
[out:csv ("name")][timeout:2500];
way["highway"]["name"]
(poly:"51.5566 0.0763 51.5734 0.0724 51.5203 0.0293");
out tags;
And this would give me a map view:
way["highway"]["name"]
(poly:"51.5566 0.0763 51.5734 0.0724 51.5203 0.0293");
out geom;
How can I get a list of bridges with their location (latitude and longitude) from an OSM file?
maybe this query may be a bit trivial or perhaps laborious, but for a project I need to obtain the bridges that exist in an osm file along with its location (latitude and longitude). Reading the openstreetmap wiki, I see that there is a procedure using osmosis but I do not know if I will actually get the information as follows: Name of the bridge | latitude | longitude bin / osmosis.bat --rx brandenburg.osm.bz2 --bp file = "city.poly" --tf accept-ways highway=motorway_link,motorway --way-key-value keyValueList="bridge.yes" --used-node --write-xml brdg_autob.osm Thanks in advance Pablo
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geom format in postGIS use to print in google maps android
a greeting, a friend happened to me a route of transportation and I step in the following format:
0102000020E610000049020000F2D077B7B23A53C0F03504C7651428C07E703E75AC3A53C07E37DDB2431428C07E8AE3C...
He told me it was a MultiLineString. I used the PostGIS function:
SELECT St_asewkt ('0102000020E6100000810200 .....');
with this i supposedly should be able to get the wkt format that I can
get the coordinates and use it on google maps api to paint a path in android, but when using it throws me empty. Help me please
I need to get something like MULTILINESTRING((0 0,1 1,1 2),(2 3,3 2,5 4)) ... to get lat lng coordinates to paint it in google maps api with android.
To summarize what I have is this value
0102000020E6100000810200 ..... and would like to paint it in android with google maps api, that's why I try to get the coordinates that function.
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How to add a method in DataMapper so I can find "all points within x distance of this latitude and longitude"?
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Whenever you're dealing with latitudes and longitudes, I would very strongly recommend that you use a spatial database rather than just two Float columns. Otherwise your queries will become crazily slow as soon as you have more than a trivial quantity of data.
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Installing
You'll need the dm-postgis plugin. The main code appears to be abandonware, but someone has updated it to work with current DataMapper. Clone dm-postgis from github, apply this pull request, and then gem install from the local directory.
You'll also find life easier if you install dm-ar-finders, which lets you use SQL queries and get DataMapper objects back.
Data model
You can then define your co-ordinate property as a PostGIS geometry type like this:
property :location, PostGISGeometry
and set it this way:
location=GeoRuby::SimpleFeatures::Point.from_x_y(longitude,latitude)
You'll probably want to create an index on your location column. Rather than Postgres's default B-tree, you want a GIST index for geographic data. dm-postgis unfortunately isn't smart enough to create this, so do it from the psql command line:
CREATE INDEX index_poi_location ON poi USING GIST (location);
The proximity query
Ok. So now you have a location field. How do you run your proximity query?
The key is PostGIS's ST_DWithin function. As the docs say, this "returns true if the geometries are within the specified distance of one another". So in your case, you'd do something like this:
POI.find_by_sql "SELECT id,name FROM pois WHERE ST_DWithin(location, ST_GeomFromText('POINT(45 90)') , 0.05 )"
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The really great thing about all this is that PostGIS puts much more complex geographical queries within your grasp. For example, in a project I'm currently working on, I'm using it like this:
shops=Shop.find_by_sql [<<-EOS,route.id]
SELECT listings.id, listings.name, listings.provides
FROM listings
JOIN routes ON ST_DWithin(listings.location, routes.linestring, 0.05)
WHERE routes.id=? AND type='Shop'
ORDER BY ST_Line_Locate_Point(routes.linestring, listings.location)
EOS
That finds all the shops along a particular route (a polyline) and orders them start-to-finish... and does it remarkably quickly.
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postgis shape file import problems
Hi I'm trying to import a shape file from http://www.nyc.gov/html/dcp/html/bytes/bytesarchive.shtml into a postgis database. the above files creates MULTIPOLYGONS when i import using shp2pgsql. then i'm trying to simply determine if lat/long points are contained in my multipolygons however my select's are not working, and when i print out the poitns of my the_geom column it seems to be very broken. select st_astext(geom) from (select (st_dumppoints(the_geom)).* from nybb where borocode =1) foo; gives the result... st_astext ------------------------------------------ POINT(1007193.83859999 257820.786899999) POINT(1007209.40620001 257829.435100004) POINT(1007244.8654 257833.326199993) POINT(1007283.3496 257839.812399998) POINT(1007299.3502 257851.488900006) POINT(1007320.1081 257869.218500003) POINT(1007356.64669999 257891.055800006) POINT(1007385.6197 257901.432999998) POINT(1007421.94509999 257894.084000006) POINT(1007516.85959999 257890.406100005) POINT(1007582.59110001 257884.7861) POINT(1007639.02150001 257877.217199996) POINT(1007701.29170001 257872.893099993) ... for points in nyc, this is very off.. what am i doing wrong?
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I think this is not issue with PostGIS. I checked input esri Shape file nybb.shp with AvisMap Free Viewer and as you see points are weird itself: However there is something interesting in nybb.shp.xml metadata file: <spdom> <bounding> <westbc Sync="TRUE">-74.257465</westbc> <eastbc Sync="TRUE">-73.699450</eastbc> <northbc Sync="TRUE">40.915808</northbc> <southbc Sync="TRUE">40.495805</southbc> </bounding> <lboundng> <leftbc Sync="TRUE">913090.770096</leftbc> <rightbc Sync="TRUE">1067317.219904</rightbc> <bottombc Sync="TRUE">120053.526313</bottombc> <topbc Sync="TRUE">272932.050103</topbc> </lboundng> </spdom> I am not familiar with those toolkit (ESRI ArcCatalog), but most probably you need to rescale your points after import using that metadata.