Hello, welcome to this lesson dedicated to cartography. Cartography could be the topic of an entire course, but in this course of geomatics elements we will give an introduction, talk about the different characteristics of maps, then we will discuss the topic of semiology. The first topic to cover concerns the characteristics of maps, with the different types, the map quality and the map components. Before we discuss this topic, we will look at a little example here of a ground shot that was made from this place, of this little village here, we have this panoramic vue and here on the map we can observe different compartments, the first that catches the eye is this whole side here this entire forest area, which is well visible on the photo and on the map. Likewise we have this part here, constructed, a village, that appears here on this part of the image and finally this whole countryside area that's in the foreground. On this map we can see a synthetic representation with adequate graphics, that facilitate the interpretation done by the user. To illustrate this, I will let you look at an aerial vue and a map for a few moments, which correspond to this sector. On this map we can see different communication channels, different types of paths and roads that we can also locate on this image. Likewise we can see the constructed part, as different isolated buildings, and the part here, central, of the town. Likewise we also have vegetation, which is represented with its different types, with orchards, here, and with a separate forest here in this region Here we see the semiology approach with graphics that allow a direct reading of the map elements. After having introduced a first map type which is the topographic map, we will see some examples of thematic maps like the choreographic map, which represents qualitative information, the chorologic map, which allows a quantitative representation, contour maps and maps with diagrammes and symbols, finally we will present a schematic example. The first example is a map, let's say choreographic, here with a geological map of Switzerland. We see the different compartments, here, of the territory, with a color code that enables to interpret the different geological layers. Effectively the legend is necessary to understand this map well. The second here is a chorologic map with quantitative values on the forest cover with an expression in percentage of the different values that are given in this color scale, and, the darker the green is the more important the forest cover is. Here in the Jura region we effectively see we have the most important values in terms of percentage of forest cover. The third example is a contour map which represent geoid undulations on Switzerland's surface. Here we have the different contour levels that represent the gap between the ellipsoid and the geoid. The last example is a diagramme map which presents the repartition of the activities in the primary, secondary, and tertiary sectors for each Swiss canton. Finally here we present an example of a schematic map with a very well known thing, namely a public transportation network which includes the different transportation lines, the bus and the metro with the names of stops and the different nodes which permit to transfer from one light to another. The quality of a map is given by a certain number of criteria which we will describe here. The first that comes to mind is the geometric precision which is the difference between the elevated position on the terrain, and the representation on the map. First and foremost this precision depends on the surveying method and on the map's scale. We can give a small example here with the geometric precision of a centerline. The second criteria is accuracy, which is the compliance with the survey specifications, and as an example here we can take the road classes. Looking at the map we see that we have a representation here for the main road, we also have the country roads so the accuracy corresponds to a good classification of the communication paths. The third criteria is completeness namely are all the objects completely represented? Are no objects absent for my map's content? The following criteria is reliability, we can summarize it as the confidence one can have in using the map. And the main criteria is the updating degree of this map. The older a map is the less reliable it is. We can see it here on this small example with the operation of a gravel pit, it's expanded on this image and on the map it isn't yet represented. The next criteria is legibility, the content's perception and here we will apply semiology rules that we will specify in the next part of the lesson. The next criteria is selectivity, which is the capacity to distinguish different object categories. <i>distinction of object categories</i> We see it on this example here, with a dense forest here, orchard areas or isolated trees. Finally the last criteria is aesthetics, which is a little more subjective but which is also part of map quality. We'll recall the notion of scale here which we have seen in the introduction of the geomatics course. We'll recall here that a scale of 1:25 000 for example means that 1 m on the map corresponds to 25 000 m in the field. Or that 1 mm corresponds to 25 m. We'll also recall the generalization effect of maps, as can be seen with the examples of a map of 1:200 000 with this small perimeter, which we find again here on the 1:50 000 and finally here on the 25 000. I'll take an example of a road here. In the field it has a width of approximately 6 m, on the map I can mesure a road with of for example 0.5 mm if I convert these 0.5 mm in 25 000 I'll obtain 12.50 m and in 200 000 one hundred meters. This values have got nothing to do with the real size of the road so here we have the generalization effect, the road size was exaggerated because they wanted to show the communication paths as important map elements. What are the components of a map? For this we choose a good example here produced by the cartography institute of the ETH in Zurich. We see a title on this map, we find a scale on the map, we find a legend with different symboles and colors, we have an orientation tool with the direction of north. We find diverse information, data sources, updating dates, production dates, here in this part of the map. In other map types there can also be a coordination grid or a synoptic overview of the area in comparison to a more general map. To end here we'll evoke the conception and production of maps. On this diagram we've got the representation of different stages with the data part, the topometric methods, and next here the classical production part, analog, which next allows to draw and reproduce the map. The updating is directly done in this loop, between the production and the complementary elements. On this example here we see the classical production, the graphical product is the central element. The process here is a, let's say analog, process even if there have been several evolutions that have allowed to digitalize maps and then to do the publishing work on the computer. As we can see here on this graphic, where we have digitalized the old map formats. With the informatics evolution the central element of cartographic production is a specialized data base with a system of geographical information. So we have here our data base and the graphical information system which is the central element that will rely on the data model here. This will allow to directly connect the survey part that will feed this data base and so also the updating process of the data base. From this data we can produce the maps with different numerical products and also find the traditional way of reprography and of paper map production. To summarize, this cartography introduction has allowed to describe different examples with different map types. We have also looked at the different criteria for map quality, which are its components and, finally, we have looked at some elements of the map production scheme. The following part will concentrate more specifically on the representation aspects that are called semiology.
