Wednesday, February 13, 2013

A mapping run to Lamphun

Lamphun isn't a city people generally think of when you're talking tourism hot spots in Thailand. It's a small city situated on the Wang River about 30 miles south of Chiang Mai as the crow flies. Neither of us had ever been there before except on the way to somewhere else.

For me the main attraction was mapping. I had never driven on any of the roads alongside the Ping River south of Chiang Mai and I was curious about them. A riverside is always an interesting place to see and drive with a motorcycle and besides I wanted to do some mapping of attractions, street names, and other Points of Interest, (POIs). So I asked Nut if she'd be interested in a little moto trip. We've not been doing much of any traveling lately so she was definitely into it. We grabbed some stuff: our cameras, my new Garmin Montana GPS, a backup paper map, and after I'd picked an arbitrary destination, a coffee shop in Lamphun, from the current version of the OSM map, off we went.

Disclaimer: I've noticed several friends' eyes glazing over when I tried to interest them in my mapping activities so if you're one of those, you might as well stop reading right now ;-)  Mapping has me firmly in its clutches!

It was a beautiful day and the ride was lovely. When I'm going mapping I use the GPS to record my track and take a camera along to photograph interesting data. (see Mapmaking 101 in this blog for more about GPS tracks and the Open Street Map project). I used to make notes on paper as I went but it was hard to keep track of where I was when I wrote the note and correlating which photo went with the note. A better method I recently turned to uses geolocated images. It's much more accurate and allows me to postpone any writing or data recording until later when I'm back at my desk.

Basically, this method uses a computer program to synchronize the GPS track from the trip with the time stamp in a given photograph to accurately position the photo on a map. All modern digital cameras record a host of data and stash it in every photograph: such things as exposure time, metering mode, focal length, ISO setting, camera name and model, and much, much more, are stored in the EXIF area inside the JPG image file. (Wikipedia: EXIF) This EXIF area can also include the latitude and longitude of the photo if your camera happens to be equipped with an internal GPS, which many are. Seeing as my stand-alone GPS is much more accurate than the present crop of GPS/camera combos and neither of my cameras have an internal GPS, I use this method.

It involves a nifty piece of free software called GeoSetter. GeoSetter reads your GPS track, loads the photos that were taken while recording that track, and then displays the photos geo-graphically located with high precision on a background map of your choice. Here's a screen shot of a map run I made a while ago in my neighborhood. You'll have to double-click to open the full size image in order to follow the discussion.
GeoSetter screenshot with selected photo in viewer and on Google Map
Here you see my GPS track in blue and a bunch of pushpins that represent the photos I took along the route. This particular photo is of a street sign displaying the street name in Thai and English that I will later place on the OSM map. I'm sitting at the corner of Srilanna Road and this small adjoining lane, Srilanna 4. The other blue markers show that I stopped at several more intersections where I took photos and recorded street names.

If you look carefully at the map in the photo you can see that the street name on the Google Map is incorrect. The road joining Srilanna Road from the left is indeed Chotana 12 but on an earlier mapping run I discovered that its name changes to Srilanna Road at the intersection indicated by the arrowhead. That's why I claimed OSM maps are often more accurate than Google Maps. The OSM mappers typically live in the area and as a result know much more about it than Google's teams of drive-by photographers and mappers can garner in a quick visit. What Google's accomplished is amazing nonetheless. They actually have Streetview imagery for much of Chiang Mai (population 1.5 million) and the huge urban jungle that is Bangkok (20 million)! I wonder what Google had to spend to get this data?

You even can see our apartment house in this map link. Drag the little yellow "pegman" onto Siriton Road and find the "Friendly House" sign at the far western end. Amazing, no?

By the way, OSM mappers are not allowed to use actual data from Google Earth or Google Maps. It's strictly protected by copyright. In the photo I'm using Google Maps as a background reference to make a point but all street names, POIs and any other data we include in OSM must be obtained legally, i.e., manually. That's one reason, aside from the fun of it, that I do these on-the-ground mapping runs.

Once I reach the geolocating stage it's merely a matter of transferring the information from the photos to the OSM. Oh, and getting the Thai name into it (in Thai script) as well. That's tricky for me but with Nut's help, doable. Somehow, the OSM project obtained permission from Microsoft to use their Bing maps as a background for their map editing interface and using that imagery we can draw ways and buildings, etc. The same copyright restriction is in place regarding names of things but roads and lanes can be more or less traced onto the map using the Bing imagery. The names, route numbers, traffic controls, etc., can then be researched and added at a later time.

Anyway, let's get back to our drive along the west side of the Mae Nam Ping. I took photos of street signs, we visited a colorful wat, or temple, of which there must be thousands in Thailand, and finally we got to Lamphun. I discovered that the highway we'd been driving and which had no special status in OSM parlance except "residential road" when I first checked it was in fact a nice two-lane designated highway, Chiang Mai Route 4032. I photographed mile-marker posts along the entire length of the highway and have updated the OSM map accordingly.

Detail: Wat Wang Sing Kham (N18.70289 E98.98351)
Shelters, like these at Wat Wang Sing Kham, are mapped as POIs
We drove directly through the city to what turned out to be a very pleasant little coffee shop right on the riverside. Different river but with similar scenery. The shop served food as well and because it was a convenient time for lunch, we ordered several items and sat in the shade nursing iced lattes while our order was prepared. The food was terrific!! The Add Up Coffee Bar is a real find (N18.57537 E99.00924). Great food, fine coffee, a perfect setting. And because it's far from the popular tourist centers, cheap even by Thailand standards.

There was a big wat nearby that had a gleaming gold chedi. Nut likes to visit the various temples we see from time to time and they're always interesting to me too if only for oogling the magnificent decorations covering every surface, so we made a stop there after lunch. This chedi had apparently just been recovered with gold leaf (gold paint?) and it shone brightly in the sunlight.

Wat Phra That Hariphunchai

Nut spotted a woman weaving saffron-colored cloth for use in the temple. She donated 20 baht to get a short session on the loom.

Because I was interested in putting interesting places as well as roads on the map, we stopped at a botanical garden on the return trip. The privately owned and extravagant Baan Phor Lian Meun Thai Medicinal Plants Garden is a work in progress. Nut spoke with a gal we saw there and she said construction has been on going for 8 years. There are many fountains, large ponds, and beautiful red stone buildings scattered about. It will be quite an attraction when finished. (View in Google Earth at N18.60566 E98.97757)

This ended our little mapping run. I hope someone using the OSM in the future enjoys these gardens as much as we enjoyed the Add Up Coffee Bar. The days are getting warmer now as spring closes in so we turned north for home before the heat of mid afternoon got too intense.