Saturday, 1 May 2010

Digital maps

Do you like to hang on at the end of the day, with a map spread in front of you, tracing on it the route you've just cycled and contemplating the part that lies before you? It's one of the best feelings isn't it? Well, that's just about all there is good about a map! From a point of view of a light-weight unsentimental cycling warrior - a map is a waste of space. The first urge after this realisation is to cut the map, leaving only the part where you wish to travel. But, there is a much more thorough approach: digitizing a map.

The idea behind it is rather simple. You can view a map as a colection of points of interest and connections between them. This info can be stored in "digital" form, using alphanumeric characters, in much smaller space then the map itself. The point of it is to store all the information on a small plastified card which is accessible "on the fly", say from a cycling jersey's pocket, without any unfolding, searching, folding and storing. Larger itineraries can be stored on several cards with only one used at any time. Such digital info may not be visualy as clear as a map, but all the info will be there. In fact your card will have much more info then a map, since there will usually be enough space on the card to store info on water points, food, accomodation, camping spots, altitute, passes, check points, usefull phrases, important telephone numbers, repair tips, ...

There are many ways to make a digitization. I will explain how I do it currently by an example of digitizing Himalaya itineraries in Pakistan, India, China and Nepal.

  1. Let me start with some definitions. A crossroad is a point where more then two roads meet. A point of interest is either a crossroad or any other feature (e.g. a town, a camping spot) that is on the road and is not a crossroad. A connection is a part of the road between two points of interests, A and B, with the condition that it has no other crossroads on it. Any network of roads can be described as a collection of connections.
  2. The first step is to draw a diagram of the selected routes, showing all possible connections and major points of interests. In the diagram the points of interests are presented as numbers, 0,1,2,...
  3. We represent a point of interest as a name and its number immediately following it. The points of interests are, for example: Islamabad0, Kashi1, Ali2, turn off to north4, Saga3, etc. The points of interests are fully defined by their numbers, the name is not necessary and may be used for clarity.
  4. We represent a connection by its ending points of interest, separated by a dash: Islamabad0-Kashi1, Ali2-Saga3, Ali2-turn off to north4. The connection is fully defined by ending points' numbers, the name may be used for clarity: 0-1, 2-Saga3, Ali2-4, Saga3-t.o.north4.
  5. We first list all the possible connections, using their numbers and names when they are introduced for the first time. As an additional information we add distances of the connections in parenhteses. All the distances will be in kilometers. Example: Islamabad0-Kashi1(1182); 1-Ali2(1323); 2-Saga3(752); 3-t.o.north4(62); 2-4(978). 3-HWY318t.o.5(167); 5-Kathmandu7(231); 5-Tingri.t.o.6(73); 6-EBC8(67). 6-Shegar.t.o.9(48); 8-9(96); 9-Lhatze10(133). 4-10(257);
In the second part we add detailed information about the individual connections. We can do that for all of the connections or just the selected ones. The detailed info for one connection looks like this:
1-2: #315: 200/TL:Yarkand. 65/Yecheng,TR. #219: 25,1500/armyB. 31,1840/V. 15/F. 41,3150. 14/F. 5/armyB. 30,3000/Kudi(426). 18,3280/armyB,F. 27,4300/RRS. 11,s217,4825. 24,3675/Mazar,TL. 13/F. 35,3860/RRS. 3/F. 17,s309,4795. 15/rrs. 16/RRS. 24,3560/Xaidulla(629). 41,3700/t.o.KKH. 20,s425,4180/Kosbel. 12,3800/Kangxiwar,RRS. 50,4000/Dahongliutan. 25,4500/RRS. 22,s534,5080,Aksai Chin. 9,4900/tent,f. 34,4735/Tianshuihai. 93,s670,5125. 2,5005/Tielong. 16,s688,5185. 12,5000,Lungmo tso. 15,s715,5090/NP. 5,5140. 10,5090/Sumxi. 10,s740,5400/!. 88,4275/Domar(1093). 17,s845,4520. 8,4300/LP. 40,4170/house,f. 2,4150/Nyak tso. 23/H,boats,fish. 15,4150/Rutok Xian,TR. 27,4240/tent. 2,4250/houses. 3,4250/t.o.Rabang. 2,4250/petrogl. 53,s1020,4715/Lame. 32,4350/cp. 6,4200/Ali2.

The meaning of it is as follows:

1-2:                   info on connection 1-2 (Kashi-Ali) follows.
#315:                  road number 315.
200/TL:Yarkand.        after 200 km turn left for Yarkand.
65/Yecheng,TR.         65 km to Yecheng, after that turn right.
#219:                  road number 219.
25,1500/armyB.         25 km to army base, it's at the altitude 1500 m.
31,1840/V.             31 km to a village, its altitude is 1840 m.
15/F.                  15 km to guaranteed food.
41,3150.               after 41 km there is a pass, at 3150 m a.s.l. Passes are represented in bold.
14/f.                  after 14 km there is probable food
5/armyB.               5 km to army base.
30,3000/Kudi(426),CP.  30 km to Kudi. Kudi is at 3000 m altitude and 426 km from the starting point of this connection (e.g. from Kashi).
                       There is also a Checkpoint.
18,3280/armyB,F.       18 km to army base at altitude 3280 m and guaranteed food.
27,4300/RRS.           27 km to Road Repair Station, at 4300 m.
11,s217,4825.          11 km to a pass at 4825 a.s.l. There is a stone kilometer marker "217" at the top.
24,3675/Mazar,TL.      24 km to Mazar, at 3675 m. Mazar is underlined, which means you can get everything there (water, food, accomodation).
                       After Mazar turn left.
...
The extent of the detail for individual connections can be different. For difficult routes like the above one, you need detail on food points and altitude. For an easy connection only a connection length may be needed, all other info may not be necessary or might be found while cycling the road itself. The info on all of the usual connections in Hymalaya region can be stored on a card with dimensions 13x8 cm - for a person with good eyesight, that is. The front page of this card would look like this:


The opposite side would have info on connections in India and Nepal (between Lahore, Amritsar, Srinagar, Leh, Delhi and Kathmandu). There would be enough space left on that side for personal info and few grace-saving chinese phrases.

"Digital maps" are an evolving subject: here is the latest one, covering the tour in Vietnam and China
Iik's latest Navigation App. 
Note some minor, ingenious upgrades to his cue-sheet (i.e. digital map) concept, 
like color-coded items and top-left notch for quick card orientation
(which could possibly be used as bottle opener). 

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