The science that studies the lands, the features, the inhabitants, and the phenomena of the Earth

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11 views

Needing to find parent zip code of a bunch of missing zip codes in the US

We're using MapPoint to export zip code / territory combinations. Unfortunately, the export doesn't include PO Box zip codes which mean that we're missing a lot of zip codes The PO Box zip codes are ...
3
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1answer
49 views

GIS through Games: Ideas or Links [closed]

I'm managing a project - http://nepanode.anl.gov aimed at improving data awareness and sharing around Environmental impact analysis. I'm struggling to come up with ways to engage users and show them ...
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2answers
50 views

Equations to convert from global cartesian coordinates to geographic coordinates

First, I needed to convert geographic coordinates (like those received from GPS) to global cartesian coordinates. I found an earlier question (How do I calculate a xyz-position of a gps-position ...
2
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2answers
63 views

Maximizing Code Performance for Shapely

I've written this code in order to calculate the percent cover of grassland within a national park, within 20km^2 of points of recorded occurrences for a species. It is designed to only consider the ...
1
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1answer
47 views

PostGIS get geometries within a radius of n meters using WGS84 [duplicate]

select * from zones z where st_intersects(z.geom, st_Buffer(ST_SetSRID(ST_Point(2.336031, 48.863172), 3857),1)); It looks like the 1 in the st_buffer is being interpreted as degrees, I need to find ...
9
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2answers
945 views

why do people use geometry to represent geography?

Historically I've mainly worked with simple latitude and longitude coordinates in a SQL Server. I stored them as a geography datatype in SQL Server, and rendered them on a variety of displays ...
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0answers
113 views

Geometry datatype to latitude /Longitude MS SQL Server

I need to convert Sql Server geometry datatype to latitude /Longitude I have just imported a shapefile to my table (geometry) This query does not work:- select geom.Lat as [Latitude], ...
2
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0answers
24 views

Characterizing territory according to its relief using ArcGIS Desktop?

I want to characterize the territory according to its relief with ArcGis 10. I'm trying to define a wide territory by its relief, but I would like to do it in an automatic or semiautomatic form with ...
2
votes
2answers
51 views

Buffering points bounded within polygons

I've checked around and didn't see this one yet, hoping somebody can help me out (preferably without code, but I'm all ears). I'm using arcGIS 10.1 on an i5 win7 machine with 16g RAM. Not a xeon but ...
0
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1answer
62 views

The ratio Pixel distance to geographical distance?

I have had this problem for several days and I have no idea to solve it. The problem is that I am trying to find out the length and width of ships from a Bing map. I got the location point (lon, ...
1
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1answer
34 views

What is the radius of earth [duplicate]

What is the real radius of earth? Google says 6378.1 km Wiki says 6371 km And there are references for 6378.7 km I'm using maximum radius 6378.7 km in distance calculation in spherical law of ...
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1answer
43 views

Equal Area Projection for Central Ethiopia (37N)

Can anybody please tell me what is the best equal area projection for central highlands of Ethiopia. I am assuming Albers Equal Area Projection. Any suggestions?
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0answers
35 views

Calculate end point Height above the MSL of the target point given a starting point, distance, azimuth and elevation [duplicate]

We need to find the end point height (from the earth surface) given the start point lat, lon, azimuth (270 deg), distance (500 km) and elevation above the horizon of start point (10 deg). The ...
0
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1answer
37 views

Postgis add Geography to function()?

i was wondering im getting different results when using geography() on different positions within a query. So, whats the most accurate way of forcing geography() over a functions with geometry ...
2
votes
1answer
220 views

POSTGIS: function st_collect(geography) does not exist

I am trying to use some Geography functions, but I am getting an error that (all) functions are not existing. I have checked other Stackexchange posts (e.g. this one), but the solutions did not work ...
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0answers
79 views

Learning classical geography - recommended literature et.c

I've been working in the field of GIS for a few years now, and there are some disciplines of knowledge where I lack a good degree of education. My educational background is that I've studied computer ...
1
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1answer
130 views

PostGIS convert GeoJSON to geography

While there are functions to convert geography to GeoJSON: text ST_AsGeoJSON(geography geog, integer maxdecimaldigits=15, integer options=0); I do not see any way to go the opposite direction ...
9
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6answers
331 views

What is the easternmost point in the US?

In his blog for The Atlantic magazine, James Fallows claimed that Eastport, ME was the easternmost point in the US. A writer commented that no, the easternmost point in the US was somewhere in Alaska, ...
6
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2answers
93 views

Min. weighted average distance from multiple points

I am a complete beginner in mapping-related topics. Still, I´ve been wondering if anyone know this problem. It might be well known, I just don´t know its name. Initial situation: nx : x geographical ...
1
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1answer
44 views

Countries with a small number of sides

Please accept my appologies if this question is off-topic here; this is the closest match to the topic of my question. I am looking for countries and states whose map is a polygon with a small number ...
5
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1answer
233 views

Is it possible that a good spatial index just cannot be made?

I have about 6 million rows with geography spatial features - they are all 1000 meter radius hexagons all over the US. There are a couple hundred thousand that would have been NULL, which I updated ...
2
votes
1answer
166 views

GeoDjango: read geometry column in geography field

I have a Django application that needs to work with an existent PostGIS database, apart from its own database. I've configured multidatabase support, created a database router, created models for the ...
2
votes
2answers
680 views

What's the fastest way to do a bounding box query in PostGIS

I have a Postgres table, with almost 2 million rows, with a long-lat coordinates field in the form POINT(-73.4938 33.2405). Supposing there's a geospatial index on that field, what's the most ...
0
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1answer
81 views

Convert an area to meters² in PostGIS

I have this query : SELECT ST_AREA(geom::geography) FROM region The (geom) contains polygons from a shapefile imported into PostGIS with shp2pgsql. I've appended ::geography, else the result of ...
9
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3answers
246 views

Where can I publish my paper for free?

Is there any magazine (or some other such place) where university students can publish a GIS/Geo related article freely (in English or French)?
0
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1answer
298 views

Maximum size on the bounding box with ST_MakeEnvelope and && and geography column in PostGIS?

I've done quite a few google searches, but haven't managed to find anything that has helped me directly. I've got a few features in a PostGIS table with a geography column. The features are focused ...
2
votes
2answers
365 views

Shapefiles for US city and Zip level

I already have the information for US states and Counties. I have the information in the Json files. I want the information for ALL US city and Zip Code information. Any leads appreciated. I cant ...
3
votes
1answer
104 views

Postgis 2.0 geographic polygon has max longitudinal range

My problem is that I have a load of geographic point data (srid 4326) in a table. A user may do a bounding box search - essentially create a polygon as follows: l_poly geography(Polygon,4326):= ...
3
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0answers
279 views

Finding poi using st_dwithin in postgis

I am not familiar with gis or writing sql, so my understanding in this field is lacking. I have a hundreds of lat/lng geographic coordinates stored in a single table called Places like this: ID | ...
1
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1answer
398 views

SQL 2012 - How can I convert MultiLineString to Geography?

I have a Geometry LineString that I wish to convert to Geography. Since the Geometry isn't valid , When I use MakeValid on it, SQL convert it to MultiLineString and than the Geography creation is ...
0
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1answer
1k views

Trying to convert geometry to geography keep failing in MSSQL 2012

In MSSQL I have LineString in Geometry type. When I try to convert it to geography using : ...
3
votes
1answer
333 views

For which operations a PostGIS Geography index is useful?

I need to do KNN- and within-region queries for POI data. I store the POI locations in a geography column. Since I understand that ST_DISTANCE doesn't use the geography index, I added a geometry index ...
1
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2answers
507 views

ST_DWithin uses Geometry or Geography type

assuming I use the following query to match the locations to a poi within 10km distance: SELECT poi.poi_id, h.loc_id, (ST_Distance(poi.geom,h.geom)*111.111) as distanceinkm FROM iut_poi_transl AS ...
1
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1answer
1k views

Distance between DB field and Point using PostGIS

I'm using Postgresql 9.0 with PostGIS 2.0 extension. I've got the table and geographic field location: =# SELECT * FROM geography_columns; f_table_catalog | f_table_schema | f_table_name | ...
3
votes
2answers
642 views

At the northpole, which way is east? [duplicate]

If a person stands on the north, or south pole. How do they determine which way is east/west?
2
votes
1answer
146 views

I would like to know about Careers in GIS [duplicate]

I am currently doing my MS software engineering. I am very much interested in GIS. I would like to know about the various opportunities available in this field and also the skills that i will have to ...
21
votes
3answers
477 views

Are ellipsoids a mathematical necessity?

The literature usually just tells us that the Geoid is complex to describe mathematically and that we therefore fit different Ellipsoids to approximate it. Are these Ellipsoids mathematically ...
2
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0answers
71 views

Critera for geometry or geography

What criteria do you need to take account to before you choose geometry or geography map? Is there a book or page about it?
3
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2answers
243 views

Several questions about using spatial data?

If you have spatial data for SQL server, can you use the spatial data (both geometry and geography) in another application for instance ESRI ArcGIS? Is spatial data a standard that every GIS ...
6
votes
3answers
563 views

postgis : is the operator <-> works for Geography also?

With recent postgres//postgis version, you can now use the operator <-> to find nearest rows to a point : Indexed Nearest Neighbour Search in PostGIS Correct me if I'm wrong, but according ...
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0answers
1k views

How to project geographic coordinates (lat/long) to a cartesian system (albers equal-area)?

I am using this matlab package http://www2.ocgy.ubc.ca/~rich/map.html#examples to project the latitudes,longitudes of my data to a specific projection. For this particular case I am using albers ...
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0answers
126 views

Graph of a specific area of USA

I am trying to get the network graph of a specific reason of USA. I have got a couple of options. One of them is using osm2po tool to extract the nodes and edge table from the osm map of a specific ...
3
votes
3answers
4k views

Insert Geography data into SQL Server 2008

Can someone guide me to or give me an example on how would one go about insert/query Geography data in Sql Server 2008 ( Polygon with 4 points and Point in specific) using C# EF or Linq2Sql. I've ...
3
votes
1answer
2k views

Open Source Tools for Mobile GIS app development?

I want to create a complete Map application with the facilities of edit geometry and attributes of layers. The server and client for the application should be some open source tools. The application ...
2
votes
2answers
598 views

Geoserver uses geometry, not geography

When using a SQL database as the store, Geoserver requires that the spatial data are stored in a geometry, not geography column. Naturally, as we are dealing with geospatial features and not just ...
3
votes
2answers
382 views

merging block group data that uses 2000 geography with 2010 geography

I would like to combine data sets from 2010 which use 2000 geography with 2011 data that use 2010 census geography. The data is from the contiguous US and is either at block or block group level. I am ...
1
vote
1answer
2k views

Issue merging multiple polygons using ST_UNION

Totally brand new at using PostGIS, my first post here on GIS. Apologies if the answer to my question is obvious! I've got regional data loaded into a PostGIS table and want to merge regions that ...
9
votes
2answers
941 views

Storing GML surface in PostGIS

I'm using PostGIS 2.0.0 and would like to store a GML Surface in a way that allows calculating intersections between that surface and various points and lines. In my case, the Surface will have one ...
3
votes
2answers
308 views

How to recalculate the the length of a geography linestring from nearby geography point in POSTGIS?

I have a geography type linestring *route_geography geography(LineString,4326)*, its a route from point A to point B. Now I have a point C near that line. I want to find the nearest point on that ...
6
votes
5answers
666 views

Where can I get (USA) county neighbour relationship data?

I need a graph where each node is a US county and each edge represents a border shared between counties. I do not particularly care about the absolute position or shape of each county (though that ...