Geocoding

I've done work before on geocoding and geocoders but somehow never wrote a separate page for it. Recapturing what I've done now...

Geocoding Services

In alphabetic order. After a little testing I am going to try LocationIQ first.

Esri

Two options:

1. Build your own and host it in ArcGIS Enterprise.
2. Use their service [1]

Google

I am just not a Google fan. I cannot update their database, so if a search fails, I cannot fix it in a timely or controllable fashion. It's hard to see what limits are and what rates are. I know I could find it but I don't care right now. I've tried it out in the past, in fact I have a page with a demo in Wiki Maps. Go forth and research it yourself: https://developers.google.com/maps/documentation/geocoding/intro

LocationIQ

I signed up here using my day job email.

Home page: https://locationiq.com/ API: https://locationiq.org/docs#forward-geocoding

Based on Nominatim. They also offer map services, but I am not concerned about that right now.

Free tier allows 5,000 requests/day, rate limit of 2/second)

Nominatim

Nominatim is the OpenStreetMap geocoder. If I put the right data into OSM, it works great for me. For example, when I lived in the Anderson Ungerman duplex, I added it to OSM. I moved to the Skopal Wilson residence and added it so I can still find my way home! Updates are near instantaneous, if you add an address you can immediately start searching for it in Nominatim. I have been adding historic houses around Astoria, as a hobby.

Usage: https://operations.osmfoundation.org/policies/nominatim/ No fees but limit your requests to one per second. Most likely not a problem.

API: https://nominatim.org/release-docs/develop/api/Overview/

If you need to do a lot of geocoding it's very easy VERY very easy to set up a Docker with a geographic region in it. It took me about 30 minutes. Then after setting it up I did updates in OSM so my data is out of date already. And I found out how poorly reverse geocoding works in Clatsop County, LOL! See below on reverse.

OpenCage

I set up an account using Github (personal account)

OpenCage is a fusion of many services.

You can use up to 2500 geocodes per day for free, rate limited to 1 per second; not a problem for my current use cases.

Because it's a fusion, you can search for many things, not just OpenStreetMap addresses.

My extensive test results

A mix of addresses and descriptions, biased for Clatsop County, Oregon.

data	situs	OpenCage	Esri	Google	Nominatim	LocationIQ	notes
32534 River Point Dr, OR	yes	yes	Wrong	Wrong	yes	yes	wrong house #
36534 Riverpoint Dr, OR	no	yes	Wrong	Wrong	yes	yes	wrong spelling
Anderson Ungerman	*	yes	Wrong	0	yes	yes
97103	*	yes	yes	yes	yes	yes
Sutton Mountain	*	yes	Wrong	yes	yes	yes
Soapstone Lake	*	yes	Wrong	yes	yes	yes
Knappa	*	yes	yes	yes	yes	yes
Hammond, OR	*	yes	yes	yes	yes	yes
Battery Russell	*	yes	yes	yes	yes	yes

\* situs address search is not designed to handle anything like this

"yes" means the result showed up correctly either on a map or as a list item if there were multiple results.

"Wrong" means it gave me only one result that was clearly incorrect (for example, Sutton Mountain but in the wrong state)

Thoughts on these results:

• I know I could make some of the results better by tuning queries, but that means more work for me!
• I know that I can improve any service based on OSM by improving the data myself.
• Conversely I have no way of improving the purely commercial/closed Esri and Google services.
• I could set up my own Esri geocoding engine but that's more work for me and still costs money.
• The base Nominatim services and the "fused" OpenCage service gave the same 100% result so at this time I don't see a benefit there.
• I think I can easily set up a React component that will source any of the Nominatim-based services and then select which one I want at run time. They should all return the same results.

This echoes what I have found throughout my explorations of closed/proprietary services versus open data / open source; they might be free or inexpensive but the open services give me more control over quality and final results. I also find the amount of work is commensurate. Phone support is available from expensive services but I generally don't find that it helps me to struggle along with mediocre commercial services then finally fall back on phone support when I can just work everything out for myself with free/open source solutions.

Reverse Geocoding

Nominatim and OpenStreetMap data

Using Nominatim for reverse geocoding gives sketchy results. Ideally it will return perfect results. You click on a house, it gives you house number. In reality it gives you a nearby street name and no house number and frequently gets the street wrong. This is because it's using ancient Tiger data and the nearest OSM object. If someone has entered the polygon for the house and then tagged it correctly, great! So if you live in a place where the mappers have entered every structure and tagged it, it will work well. In my place (Clatsop County currently), it does not.

I have to upload good structure data first. :-) Once I do that, it will be perfect.

Esri ArcGIS

Accuracy in my admittedly difficult tests are poor. I am thinking I might need to set up my own geocoding service using county roads data, sigh.