Friday, 30 January 2009

Little River Rail Trail II

This Saturday just passed, I took my second outing on the Little River Rail Trail. Since my first visit in June 2006, the original route west of Motukarara has been extended another 3 km into the terminal township, and another section from Prebbleton to Lincoln, consisting of a sealed pathway paralleling the actual rail route, has also opened in full. My focus today is on Motukarara – Little River, and starts with my arrival at M by car and getting ready to set off on the 24 km ride to LR. Motukarara now boasts the original station building, albeit on a site 900 metres south of its original location, and a length of track with a couple of wagons on it. Today in the hot summer sun, the trail surface is dry and poses little resistance; the first time, winter rains made it sticky and slippery. Still, I’m not able to get up as much speed as on a sealed road.

Setting out from Motukarara, every few minutes I stop to photograph some point of interest, such as a curve, or a bridge, or some other geographic feature of the line. This makes for slow riding; in the first hour I only cover 9 km.  With the GPS along, I don’t bother recording anything else; later at home, the computer will match the GPS timestamps to photos automatically and so create a pictorial trail of the journey (which you can view here). It is a very hot day and I am well covered in clothing and sunscreen. Another nice little touch alongside the line is the milepegs, full miles, halves and quarters, here and there. This line was never metricated, after all. Just after the first bend out of Mot, we encounter the first of numerous bridges. Most of these are on the original alignment, using the original abutments or in some cases new concrete ones. We have now turned almost due south and are continuing for the moment as a slightly raised embankment in rolling open country with the main road some distance away but gradually converging, and at the 11 mile peg we are briefly alongside. Nearby at Seabridge Road, we have the first public access to the trail since leaving Motukarara. Soon we turn south-east, meeting the highway again on a bend, and cross a stream with old piles in the waterway.

We are now on the shores of Lake Ellesmere, where the stone-faced embankment has been a distinctive feature of the landscape for more than 100 years. Up till now, all the bridges have been narrow one-way affairs, but a few km further on, we encounter the only such structure that is the full width of the embankment. Perhaps this is the case because it is largely a deck on top of the original superstructure/substructure, which appears to have been left mostly intact when the line closed. Soon the dry lakebed resembles mudflats; the tide is out, so to speak. Further on, at another meeting place with the highway, we reach Kaituna, our first station since Motukarara and almost 8 km from it. The trail deviates around the station site which is on road reserve and still includes remains of a loading bank. Just past the 13 mile peg we come to the unusual Kaituna inlet bridge, which is a humped structure to raise the trail above the waterway, probably to allow navigation. Very soon the view is dominated by a raised mound of rock on the horizon. We have reached the Kaituna quarry, where the stone pitching that protects the embankment in these parts was broken down from big rocks with explosive blasting. Clearly there was a siding here as the curved embankment and remains of sleepers show. The quarry also yields the remains of a number of old rail wagons, which evidently were pushed into the siding in some long distant past era and burned when their useful life had come to an end. Two small brick huts were formerly used to store explosives; the more accessible of the pair turns out to have a large cloud of wasps surrounding it, so I beat a hasty retreat back to the trail.
The lake continues as a dominant feature of the local landscape until we pass another meeting place of the highway, then the longest bridge on this entire trail, and eventually turn north-east at the Birdlings Flat township turnoff. Here also is the eponymous station with its old loading bank still present. We are now heading in the direction of Lake Forsyth, but still have to pass over several concrete culverts, the first such structures we have encountered so far. Passing the 17 mile peg we are soon alongside the lake, which will be our companion all the way to Catons Bay, a public roadside rest area and the original 2006 terminus of the rail trail. The embankment winds its way in and out alongside the lake, more or less following the shoreline, and in parts closely sandwiched by water on one side and asphalted highway on the other. The first trees of sufficient size to provide meaningful shade are a welcome feature of this part of the trail. After stopping to photograph a few flocks of black swans, I am soon at Catons Bay. Here we have travelled some two-thirds of the length of the lake and soon pass its head another kilometre on. In this last part of the trail there are a few rises and dips, and several deviations when we are getting too close to the road. The main challenge faced in completing this section has been the old level crossing near the Little River Hotel; in a 100 km/h section of highway, it makes things quite dangerous for pedestrians and cyclists. Eventually after a lot of discussion, a “temporary” deviation has been constructed to continue the trail on the south side of the highway, rejoining the original route after 750 metres.

Today I choose to cross the highway, very carefully, and then follow the original embankment until it gets too far from the road, then go back across and onto the trail, which follows a stream bank around to Wairewa Pa Road and an easier/safer crossing of the highway in a 70 km/h zone. From here I ride along the highway a short distance and then turn off down Barclays Road to ride alongside the original formation past the recycling depot and down to the Little River Station. The original buildings were retained by Banks Peninsula Council after the line closed, and are still standing today. The locals and the Rail Trail Trust have laid some bits of track and mounted restored items of rolling stock on them. Here my ride comes to an end, after 24 km and nearly three hours. I think that the “temporary” extension is most useful and should become permanent. After I meet up with my ride, we are soon on our way back to Christchurch. Some way past Motukarara, the embankment trails off into the distance while the road route pulls rapidly away. This section promises to be another interesting ride and I trust that the project to reopen it to the public is making good headway.

Friday, 2 January 2009

Mapping photos with GPS and Google Earth

Since I bought my first digital cameras four years ago, there has been widespread development in the availability of virtual globe software which lets us do many useful geographically orientated things, such as mapping points of interest and the locations of specific photographs of scenery. There are two specific services which are integrated with Google Earth for photolocation. These are Picasaweb and Panoramio. At this stage I have stuck with Picasaweb due to my dislike of having to duplicate effort in Panoramio, and its lack of sophisticated upload tools like the Picasa client software that Google produces. However, Panoramio pictures can be displayed as an integral layer in Google Earth. I hope that Google will introduce a similar level of integration of Picasaweb for those of us who prefer its capabilities so that we can submit photos directly from Picasaweb in our existing and new albums.
The main subject of this post is how to map photos using Google Earth and Picasa. In the beginning of 2008 I created my first mapped albums in Picasaweb, as the client software features the ability to geotag individual pictures. It does this by using Google Earth as a user interface to find the coordinates of a specific place which the user nominates as a photo location, and then using the EXIF standard it adds coordinate information to an existing JPEG photo. As my albums can incorporate up to several hundred pictures each, it takes a lot of time and effort to locate each individual picture. As well as that, you have to be able to work out where each picture was taken. On the train trips that I did last January, and some other trips that I have created other albums for, because my knowledge of the routes was very good, I could work this out without too much trouble. But on a recent trip I did on the Waipara river, I couldn’t work out where everything went because I didn’t know the area.
The easiest way to get around this problem is to batch synchronise data from a GPS unit with photos. A $200 handheld GPS from Garmin will automatically create a track of locations over a period of time while it is turned on. This track can be downloaded to a PC and then using appropriate software the timestamps of the GPS trackpoints can be synchronised to specific pictures using the timestamps that your digital camera embeds into each picture that it takes. The software can then save this information in a file that can be imported into Google Earth to display the photomap.
A recent trip to Quail Island was the first trial of this system for me. The only real issues encountered were technical limitations in Google Maps and Google Earth, and the GPS’s batteries going flat. My equipment was:
  • Garmin eTrex H handheld GPS. This is a high sensitivity, basic unit at the lower end of the price and spec range. It is a rugged water-resistant design, and the high sensitivity means it is better to use indoors (such as inside a moving vehicle) when environmental conditions make it more difficult to receive the faint signals from the GPS satellites.
  • Garmin serial PC data cable. This connects the GPS to the serial port of a PC. Your computer will need to have a 9 pin serial port (the old RS232 style). A lot of modern computers do not have these ports and you might also need to purchase a USB to serial adapter at extra cost if your PC is in this category. Garmin still provides only the RS232 interface on its most recent lower end units. This is a lot slower than USB, but it works satisfactorily and the cable can be connected and disconnected on the fly.
  • GPS download and geotagging software. You do not need to buy this from your GPS manufacturer, as typically like the data cables, such products are unnecessarily expensive. A lot of GPSs are supported by third party products. I used the free EasyGPS software to download the tracks and geotag, which it does by comparing timestamps.
  • A geotagging compatible web album or software system that can display your tracks and photos automatically in their correct locations on a virtual globe. I use Picasaweb, Google Earth and Google Maps as needed.
First thing is to get your GPS set up. The eTrex automatically records the track by default as long as it is switched on. Make sure the batteries have enough juice in them to last for the whole of your trip. Secondly, ensure that the clock(s) on your camera(s) are very accurately set. Get a time signal from the radio (or somewhere) and sync the clocks to that. The more accurate these are, the more accurate will be the locations of photos that can be determined by the geotagging software. Then, on the day of your trip, just turn on the GPS before your trip starts, and take your photos. Simple :)
Once you’ve returned, download photos to your PC and the track data from the GPS. Then, select the photos you want and carry out any additional processing needed. I use IrfanView to batch resize my photos and add a copyright caption which also shows the date and time the picture was taken. For public web display I resize to 960x720. The next step is to geotag. In EasyGPS you simply tell it to add photos to the correct track. This causes it to write the coordinates of each photo directly into its EXIF headers, by matching GPS and photo timestamps. I had no problems with this as I synched my cameras’ clocks within 10 seconds of GMT. The GPS gets its time automatically, of course. You just need to make sure it knows what your timezone is so it can adjust the timestamp automatically to your local time.
Once finished geotagging in EasyGPS, save the track as a GPX file for use with other software. GPX is the open GPS XML format for exchanging GPS data. My next step is to open the GPX file in Google Earth, which the current free edition has the ability to do. This lets me edit the tracks to remove parts that are irrelevant to my map. I discarded the picture information from the GPX as it is static to the hard drive locations of my PC and therefore not much use on the internet. Using Picasa client (version 2.7 is recommended), I then captioned each of the photos on my PC and then bulk uploaded them to a new Picasa Web Album of my choice. This causes Picasaweb to automatically create a map of the locations of all the photos of the album. I can then download this to my PC (using the “View in Google Earth” link) and open it in GE. I then combined the photo map from Picasaweb with the GPS tracks that I imported from my GPS to create the final map of my trip. That trip was then imported to Google Maps to allow it to be embedded for display in a blog posting. All of the thumbnails on this map will automatically link to Picasaweb to display the photo from my web album.