Best Gis data map providers of country polygon borders

There are many companies offering solution for these data, and part of these will be reviewed later in this post. Basic data formats that are offered from these companies are Ersi Shape (.shp) shape files, MapInfo (.tab), Oracle Dump/Import (11g) etc. Please understand that for my research I wanted maps that firstly provide best precision results using geo point location and has good complex polygons for country borders. That was most important for me. Maybe there are better maps online for specific purpose (town, streets, sea) but these requirements where not important for me. I just wanted to see which GEO data would behave at best near borderline conditions. And yes you can surely use google maps API etc. I needed independent source, that will not rely on any calls to a third party but all data to be originating from my own services.

Solution:

logo-ogpThe International Association of Oil & Gas Producers (EPSG)

 

WebPage: http://www.epsg.org/

This is an absolute winner for me. I stumbled across it when I started searching for map data on internet with absolutely NO clue where to go and who to ask. It has very nice polygons, ISO alphanumeric codes. And most important of all it has very nice solution for coast borderlines – it includes country’s water borders, making sure that whichever coast the geo point is on even with near miss of couple of meters, will define it inside the specific country.

Research:


GIS Data testing

Gis Data testing is being done with Google Maps as a valid and concise reference. The Geo Points taken from Google Maps are then being tested in the imported MS SQL environment from the Gis data map providers. These points are mainly borderline points in order to determine the level of precision of the Gis map data. SQL Code for the test as example:

DECLARE @TestingPoint geography;
SET @TestingPoint = geography::Parse('POINT(12.448959 41.905033)');
SELECT * from [Maps].[dbo].[adciWorld_Admin_1]
where geom.STContains(@TestingPoint) = 1

 

Gis data map providers

 

1. American Digital Cartography (ADCI)

Web Page: http://www.adci.com/

Offers licensed Geo Maps. Fairly good polygons in their shape files, and these where my first choice to go. Except for one thing – the polygons along coast line are very precise and the POINTS located there would return false negative. See table for random point testing.

 

gis-adci

Sample polygon sketch

2.The International Association of Oil & Gas Producers (EPSG)

Web Page: http://www.epsg.org/

The EPSG Geodetic Parameter Dataset is maintained by the Geodesy Subcommittee of the IOGP Geomatics Committee. Somehow they hold the geo earth standard used in database calculations for spherical surfaces. Data set is given upon registration freely, but there are terms and conditions. Very nice solution for the coastline borders. Numerous data and sub data sets included, even more that you need.

gis-epsg

Sample polygon sketch

3. Natural Earth Data (NED)

Web Page: http://www.naturalearthdata.com/

Natural Earth was built through a collaboration of many volunteers and is supported by NACIS (North American Cartographic Information Society), and is free for use in any type of project. But it has very poor polygon set. I used them only as a reference and comparison.

gis-nad

Sample polygon sketch

4. Harris MapMart (HMM)

Web Page: http://www.mapmart.com/

They provide world’s premier satellite, aerial, elevation, vector and LiDAR data. But I guess they are more satellite imagery oriented. I could get just a sample of their data set and I wasn’t happy with it.

gis-hmm

Sample polygon sketch

Sample point comparison on map data

Google maps is used as accurate reference for this point comparison. This is a simulation where input is GIS data (longitude, latitude) should respond with most precise approximation of country the specific point is in. As you can see from the table, disputable points are being used. That is, points that are between states, points that are near coast line and on the docks. Inland points are not so much included because if the maps can correctly calculate on their borderlines, that means that there should be no problem what so ever to do inland calculation.

comparisontable-gis

Leave a Reply

Your email address will not be published. Required fields are marked *