In recent years, the falling price and increasing performance of hand-held GPS units has made them a common item in many backpacks and gloveboxes. These high-tech toys can tell you your location anywhere on the surface of the earth with at least 100M accuracy.

Typically, the average user will use the GPS to mark waypoints such as a favourite fishing hole, hunting stand, or campsite. In the course of the traveller's journey, he'll turn-on the GPS every now and then to determine his present position and the direction he must follow to reach one of those waypoints. For this type of usage, the hand-held GPS is great. It's when he wants to transfer GPS data to and from a map that things become annoying.

To get the waypoint of a location that you've never visited before, you have to find the location on a map, look-up the coordinates and then enter them into your GPS. The majority of hand-held GPS units do not have an alphanumeric keypad so entering waypoint coordinates is tedious, especially if you have several waypoints.

Even more tedious is the task of transferring the information you've captured with your GPS onto a map! Imagine all those points you need to read from your GPS' display and then look-up and plot onto a map. Not much fun.

Fortunately, Spectrum Digital Imaging has an easy solution consisting of two parts:

1. Ozi Explorer
2. Spectrum Digital Imaging's Map CDs

Ozi Explorer

To make your own map, you first need to scan it into your computer in a standard graphics format such as .bmp. Next, it must be calibrated. This entails clicking on points on the image and defining their latitude and longitude (or easting and northing if using UTM). The more calibration points you provide, the more accurate the calibration will be. Even if your map doesn't have the lat/lon coordinates on it, if you know the coordinates of some recognizable points on that map, you can still calibrate it.

Here's an example: when I went down to Walker Valley earlier this year, I recorded my track on my Garmin GPS III+. Several months later, Paul Gagnon sent me a map image from a free pamphlet that he had picked up while down there. It wasn't a topographic map but it was drawn to scale. I loaded the scanned map into Ozi Explorer. From the track points on my GPS, I could figure out the coordinates of three points on the map. With the map thus calibrated, I uploaded my GPS data into Ozi Explorer which then overlayed the data onto the map image. Here's the result:

Not bad for a map that was scanned from a pamphlet, eh? The track matches the paths on the map quite well. The benefit of this exercise is that now I know exactly which trails I took, along with the unmarked shortcut we took to get back to the pavement. As you can see, I've labelled it, along with the location of a locked gate on the B-1000 trail. I can now print out a copy of this map for the next time I go down there and if I want to, I can include the shortcut as part of my map. And that's the beauty of using a program like Ozi Explorer. It lets you create CUSTOM MAPS.
 

BC Maps on CD-ROM

92G1 MISSION 92G2 NEW WESTMINISTER 92G3 LULU ISLAND 92G6 NORTH VANCOUVER 92G7 PORT COQUITLAM 92G8 STAVE LAKE 92G9 STAVE RIVER 92G10 PITT RIVER 92G11 SQUAMISH 92G14 CHEAKAMUS RIVER 92G15 MAMQUAM MOUNTAIN 92G16 GLACIER LAKE 92H3 SKAGIT RIVER 92H4 CHILLIWACK 92H5 HARRISON LAKE 92H6 HOPE 92H11 SPUZZUM 92H12 MOUNT URQUHART 92H13 SCUZZY MOUNTAIN 92H14 BOSTON BAR

92I3 PROSPECT CREEK 92I4 LYTTON 92I5 STEIN RIVER 92I6 SPENCES BRIDGE 92I11 ASHCROFT 92I12 LILLOOET 92I13 PAVILION 92I14 CACHE CREEK 92J1 STEIN LAKE 92J2 WHISTLER 92J3 BRANDYWINE FALLS 92J6 RYAN RIVER 92J7 PEMBERTON 92J8 DUFFY LAKE 92J9 SHALATH 92J10 BIRKENHEAD LAKE 92J11 NORTH CREEK 92J14 DICKSON RANGE 92J15 BRALORNE 922J16 BRIDGE RIVER

If you bought these maps in printed format, they would set you back around CAD$400. SDI's distributors sell that CD for around CAD$129. Quite a savings if you don't need all those maps in hardcopy format.

Armed with a program that can overlay map data with GPS data and a wealth of digital maps, we can now do neat tricks with our GPS. The latest GPS units feature built-in maps but unfortunately, none have useful back country map data for Canada. With SDI's maps and Ozi Explorer, we can make our own built-in maps even for those GPS units which don't have a buit-in map feature. All we have to do is load a map and use the Track feature to trace the trails we're in which interested. Once the tracks are completed, they can be uploaded to the GPS.

If you have a notebook computer, you can use Ozi Explorer in real-time mode. The GPS can be configured to continually output its location to the computer running Ozi Explorer. Ozi will display a moving cursor showing exactly where you are on the map. If you reach the end of the current map, Ozi will automatically search your map inventory and load the next map in your path.

On our recent trip to Clear Creek, my plan was to hike the trail past the hot spring to check its condition and see if it was possible to connect to the Spuzzum Creek trail which started at the Fraser Canyon. Prior to leaving, I started up Ozi Explorer and loaded one of SDI's maps of the Clear Creek area. I marked useful waypoints such as the end of the Clear Creek trail, nearby lakes and the end of the Spuzzum trail. I also traced the last part of the Clear Creek trail as a track. Then I downloaded the data to my GPS.

At Clear Creek, I was able to use the GPS to figure out how far we were from the end of the trail and how much further we had to hike to reach the Spuzzum Creek trail. I also used the GPS to mark the exact location of the hot springs cabin as well as a sidehill. Here's a screen capture of the map containing the waypoints and the track I created:

SIDE	Sidehill which marks the beginning of the Clear Creek trail.
HOTSPR	The original location of the cabin at the hot spring.
SM LK	A nearby lake.
CC END	End of the Clear Creek trail, according to the map.
Purple line	I created this path on the computer. When downloaded to the GPS, it serves as a kind of built-in map showing me the trail's route.

As you can see, the combination of a GPS, Ozi Explorer and SDI's topographic maps is a valuable tool for back country exploration. Another use for which it is ideally suited is as a trail database system. A group of friends or club members could record trail information on a GPS and upload the data to the club's "trail librarian." This accurate, graphical trail information would then be available to all other members of the group. This would also be a valuable source of information when dealing with land use issues. Imagine a club showing up at a land use meeting and presenting a detailed inventory of their local trail system.

I'm sufficiently impressed with this combination of tools that I will be using it for future trail exploration. SDI has also given BC4x4.COM permission to use its maps for trip report illustrations so you can look forward to online maps tracing our adventures.

...lars