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12 July 2007

Batch Geocoder to ArcGIS

Batch Geocoder to ArcGIS Tutorial

(for getting Latitude and Longitude for Postcodes and Addresses)

Now this requires a bit of prior knowledge on Geocoding and Basic GIS Skills

Thanks to Google for providing the UK Geocoding in the Google Maps API

Have a set of addresses or postcodes ready.

*but if you intend to do a huge amount of geocoding it's politer to have your own api key rather than using others

example postcodes used in this example (can be 5 can be 50,000)
AL1 1HH
AL1 1HJ
AL1 1HQ
AL1 1HR
AL1 1PW
AL1 1RZ
AL1 1SD
AL1 1SE
AL1 1SF
AL1 1SG
AL1 1SH
AL1 1SN
AL1 1SQ
AL1 1ST
AL1 1SW
AL1 1XU

or use Addresses like
10 Downing Street, Westminster, London, UK
(can be your own list of clients, businesses, store locations etc)

where do they go?

Either
http://www.batchgeocode.com/
or
http://www.gpsvisualizer.com/geocoder/

(for your own version flow instructions at bottom of gpsvisulizer page)
or
http://www.wotton.org/map/batchgeo.html
(recommended for ease of use)

batch geocoders to gis
Copy and Paste in the top light blue box, wait until the alert shows the copy and paste from the bottom green box into a New Spreadsheet.

batch geocoders - pasting

Paste into Open Office Calc or Excel with the correct delimiters.

batch geocoders pasting add decimals

Make the pasted lat and lng's six figures in decimal places
save the spreadsheet


batch geocoding xls arcgis
Add the Spreadsheet to ArcGIS (will need a double click if more than 1 worksheet is in the file)

Use WGS84 Geographical Projection to set the Excel Spreadsheet into the correct projection

Use Add XY Data add the data by Lat/Lng and an event theme will be created, this can be exported out as a shapefile or geodatabase.

Important Note: Geocoder Accuracy
ALWAYS check Accuracy - this shows that the all Geocoders have limitations
This compares Codepoint (accurate to 100m) to the Google Geocoded Postcodes and there is approximately +/- 150 metres error in their location.

batch geocode check accuracy in GIS

Blue is OS Codepoint in Geographic WGS84
Red is the Google Geocoded Postcodes
(used for a comparison only!)


The method is useful for small datasets, depending on your use.
It could be easily changed to load the geocoded data into a MySQL or Postgres databases for spatial retrieval and added back on to web mapping applications.

Yahoo does Geocode UK Addresses (in some cases more accurate) but it's limitation is that it can only be used on it's on Mapping API and the Geocoder is limited to just 5,000 requests per 24 hours.

For Manual Geocoding
Please use the Official Example:
http://gmaps-samples.googlecode.com/svn/trunk/geocoder/singlegeocode.html

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3 Comments:

At Wednesday, August 01, 2007 4:40:00 pm, Blogger Ketan said...

Hi, many thanks for the above tips.

I just needed some more help please, as I'm not a Mapper! I am currently a masters student in vision sciences at the university of mancheseter, and am looking at the referral of glaucoma patients to the Manchester Royal Eye Hospital.

I have a database of 2024 patients, and I wanted to plot where abouts in Manchester the patients were coming from and to see if there are any trends relating to different postcodes or manchester wards in relation to socioecomic status and numbers of referrals.

Using the above tips I managed to geocode their postcodes and plot them using Arcmap. (again very new to the package - have only been using it for 2 days).

The only problem is that I haven't been able to find a suitable raster data set of Manchester to superimpose these points. At Uni we have access to Digi map, but when I use the raster layers on there, it say they contain no spatial data, so I can't plot my points on top of them.

So I was wandering if you could advise where I might be able to download a suitable manchester raster layer. It just needs to be very simple, and ideally if I can break it down into postcode regions or wards.

Many thanks.

 
At Wednesday, August 01, 2007 5:44:00 pm, Blogger Mapperz said...

Ketan, What Scale and what content of raster data are you looking for?

Web Based?
Desktop based?

Your be lucky for free raster based large scale data in the UK.

But if studying you can get a discount from Ordnance Survey.

Mapvu is a cheaper alternative
http://www.mapsinternational.co.uk/mvwallmapsindex.asp

Mapperz

 
At Wednesday, August 01, 2007 6:34:00 pm, Blogger Ketan said...

Many thanks for your speedy reply Mapperz.

Ideally I need a desktop based. I created the following using gpsvisualizer:
http://limbachia1.googlepages.com/AllReferralstoReferralRefinementOpto.htm

I'm not sure about about scale, but so long as it can display all the points like in the googlemap one it should be ok.

Content wise, All i need is an outline of manchester divided by postcode areas or wards. It doesn't need to have any other detail.

I hope that makes sense! And many thanks again for the advice.

 

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