Navigation Part III - GPS Unit

Introduction

For the navigation subject, the preparation before going to the field was already covered, and in the last week, the first field activity was done using the traditional method: map and compass. Now it’s time to deal with the use of a GPS unit for navigation. However, the map produced before won’t be available at this point. In the next exercise, though, not only the GPS unit will be used, but also an improved map for navigation. Finally, a comparison of all the methods along these weeks will be done.

This week’s activity, the navigation with the GPS unit, occurred on March 11^th, 2013 and the main goal was to analyze how well this technique works, comparing to the traditional way with a compass and map.

Methods

Considering the depth of the snow in the last activity and the permanence of the weather conditions, if not worse than before, it was necessary to improve the clothing preparation. Then, water-proof and a higher number of layers were used.

The only equipment used in this exercise is a Garmin Etrex GPS Unit (Figure 1), supported by a table containing the UTM coordinates for each point. After a quick overview about the basic use of the unit, each group was directed to the corresponding course.

Figure 1 – Garmin Extrex GPS Unit

This report refers to the procedures taken by the Group 1, who navigate by the course number 2, from the first point to the sixth point. The track log mode was turned on without any change in the settings. For the first points in the course, a method was applied to find them; and then another for the further points. The first consists in fixing one of the coordinates and, after that, fixing the other coordinate. This way takes a longer time, but would guarantee to arrive in the correct place. Then, the X coordinate was taken in consideration, and after being in the correct place in the X axis, the same was done to the Y coordinate. By looking at the changes in the coordinates on the unit screen, it was possible to guarantee that the direction was correct. The internal compass of the unit was also used to be certain of the direction.

However, after two points, it was noticed that a more convenient and effective way could be used to navigate from one point to another. The GPS contains a tool called “Where to?”; the coordinates for the target point are input there, and the unit will automatically show the direction on the compass and the distance to there. With this way, a lot of time was saved, and it wasn’t necessary to keep the eye on the GPS all the times, allowing to be aware of the environment around more carefully. Also, the direction and distance were automatically update as the group moved, so there were no worries about the lack of precision in case the track was missed because of some obstacle – such as elevations, dense vegetation or restricted areas. The precision was never perfect since the area consists in woods, but the margin of error, based on the PDOP, could be constantly monitored and kept in an acceptable level.

After passing through all the points, the tracklog was turned off and later downloaded in the computer. For that, it was necessary to examine the DNR Garmin software, connecting it to the GPS unit by an USB cable and acquiring the data stored in it. The data can be exported as a shapefile based on points or lines. The first choice was line, but later on it was known that the ideal type would be points. Then, Arc Tool Box was used, and the command “Feature Vertices to points” enabled the conversion from lines to points.

All the students were supposed to follow the same process and all the data would be available for the class. The files were located on a protected folder, reason why it was preferable to create a new geodatabase in the personal folder – where editing is allowed – and import the data (Figure 2). Besides the geodatabase, dataset were created to maintain organization and guarantee the coordinate system uniformity. In this case, the Eau Claire County System was used: since the tracklogs would be used only for presentation purposes, it was no longer necessary to use the UTM coordinates. In this case, the coordinate system covering the smallest area will have the minimum distortion and that’s why the county coordinate system was chosen.

Figure 2 – Geodatabase

However, as it happened before, some track logs were available as lines, so it was again necessary to run the “Feature vertices to points” command in Arc Tool Box. After having all the data prepared, three maps were elaborated: an individual map containing my own path in the activity; a group map referring to the tracks from each of the group components; and, for last, a map containing the paths taken for the whole class components.

The course points were also available, so they were added to all the maps and symbolized accordingly to the course they belong to. Also, it would be interesting to have an idea of the shortest path that could be taken between the points. For that, it’s necessary to create lines between the points. The command “Points to Line” in the Database Management in the Arc Tool Box was used to have this result. However, if it was simply run only inputting the source and output, there would be a connection line between all the points. That wouldn’t represent the idea of three different courses, as it’s needed. Then, the “Line Field” was use to indicate which field in the attribute table would differentiate the lines created.

Figure 3 – Use of Point to Line tool

Then, it was possible to symbolize both lines and course points accordingly with their course. Labels were also used to assess the readability of the maps. Different levels of emphasis were used depending on the map being made and the amount of data associated. Transparency and lighter colors were used when these features were not the main point of the map.

For the map with the track logs of all the students, they were separated in the corresponding groups and each group would have the same color to help the interpretation. However, when dealing with the group map, the three track logs were symbolized in different colors to analyze the differences and similarities between them. In this case, since the other courses were not part of the analysis, a higher scale focusing only in the second course was use. The same scale was used for the individual map, as well as a higher tone for the points and lines of the course, so a comparison would be easily done.

The maps were essential to support the analysis of accuracy and precision of different collections, as well as to notice different behavior taken in the path, depending on the obstacles found. The use of the satellite image was important to recognize different types of vegetation and its effects on the paths taken.

Discussion

In terms of accuracy, it’s interesting to examine the individual map (Figure 4). In the fourth course point, the GPS acquire some points close or even on the highway, where the group clearly didn’t go to. The same problem doesn’t occur in most of the other places and although the area was vegetated, it wasn’t much different for the others.

Figure 4 – Individual Track logs map

Thus, the most reasonable explanation for this lack of accuracy at this point is the fact that in the fourth course point, the group stopped for a moment to rest and set the GPS to the next point (Figure 5). The longer time at this point can be noticed by the high amount of points taken there. When dealing with a path, collection done by a GPS have the accuracy compromised when the GPS unit stays for a longer time in the same position. It’s different when collecting a point feature class, where the unit collects a number of points, ignore the outliers and calculate the average of the others.

Figure 5 – Quick stop to rest and set the GPS to the next point.

It’s also possible to notice that after the sixth point, the collection soon was stopped. That was not intentional, but the battery was low and after the sixth point, there was no much need of looking at the GPS so frequently, then it turned off automatically and this was only noticed later.

As well as in the last exercise – with the map and compass – the snow depth in this activity was really high (Figure 6), compromising how fast the group could move between points. Then, a tactic used was to avoid hills and dense vegetation areas – that would compromise even more. So, the natural trails were used as much as it was possible. This involves a higher distance, but would be more effective.

Figure 6 – Snow depth reaching Andrew’s knees.

This behavior taken in the paths can be notice both in the individual map, but also in the group map (Figure 7): all the track logs follow the contour lines, showing that there was not a high change of elevation by avoiding hills. Between the fourth and fifth point, the track taken was also longer than it could be, because an area closed by fences was being avoided. Another feature avoided was the dense vegetation at east, the group only got inside tit when it was really necessary to get to the point. To walk through it was complicated, so the trail was preferred.

Figure 7 – Group Track logs Map

As said before, the settings for the track log in the GPS units were not changed before going to the field. This is very clear when comparing the three tracks in the group map. There’s much more points in Kent’s track log, making it even look like a line, while the other two track logs have a smaller amount of points collected. This is part of the settings for the track log, you can set the time interval for the data collection: the lower the time interval, the more points you will get. It’s necessary to find the balance between having a good amount of data, but without compromising the file storage in the GPS.

For last, a map covering the tracks taken by all the students in this class (Figure 8) can give a general idea of the activity. There were six groups divided in three courses, odd number groups would go to the points in ascending order, while even number groups would do it in descending order. Groups 1-2 were supposed to be in the course two, groups 3-4 in the course three and groups 5-6 in the course one. More or less, all the groups were able to navigate over the corresponding courses and the paths taken were similar. Thus, it’s possible to affirm that the groups had kind of the same idea and completed the task successfully.

Figure 8 – Class track logs map.

Conclusion

The activity for this week proceeded much smoother than in the week before. The points were easier to be found, the navigation itself took less than two hours and all the points were covered. However, that doesn’t necessarily mean that the GPS navigation is better than with the map and compass. Specifically for this group, because mistakes were made, the navigation with map and compass was complicated. However, if the appropriate steps were taken, trusting in the compass, a different scenario would be in comparison.

Still, the step count and the need to stop every once in a while to maintain the compass direction delay the process; while with the GPS, the path is automatically corrected in case it goes out of the direction. Then, in this matter, there’s no doubt that the GPS navigation is more effective than with the map and compass.

In the other hand, the precision can be an issue when dealing with the GPS. As mentioned, when the unit is standing in the same place, the accuracy is compromised. It was essential to have three units per group: sometimes a single unit had a high error, putting in doubt if the flag found belonged to the appropriate course. In these occasions, to check other GPS units was useful to guarantee the right placement. The problem with the GPS lack of accuracy is that it’s not possible to know which element has a problem: direction or distance. By using the compass and pace count, the analysis of which one might be dubious.

However, these errors didn’t compromise the navigation, which happened very well, even being in a dense vegetated area – where the PDOP tend to increase. Therefore, it’s not a surprise that the traditional mode was taken over by the technology of the GPS. Especially when dealing with areas not affected so much by multipath effects and other types of errors, there’s no doubt that the GPS navigation is more effective and appropriate for the fast paced routine most of companies and governments have. It doesn’t mean, though, that the traditional technique should be neglected. Although it’s not the preferable way to acquire data or navigate, it should always be known by the geography professionals, so they know how to deal with their tasks if the technologies fail on them.

Navigation Part II - Map and Compass

Introduction

The last report covered the map making and preparation for the following week activity. Then, this report refers to the navigation activity itself occurred at the Priory on last Monday, March 4^th. As said before, this is one piece of a bigger exercise that consists in analyzing different ways to navigate. For this week, the method of navigation was the use of a compass and a reference map. In the following weeks, the navigation with a GPS unit will be covered. The map used for this activity is the one produced in the last exercise by the group, along with the compass; the space count will also be used.

Methodology

The activity consisted in navigating over different levels of elevation, inside the woods, during the formation of a snowstorm. Thus, appropriate preparation was necessary. The first step was to dress properly to go to the field.

One important feature that was not included in the maps yet was the course points where each group would need to go to. The feature class for these points was not available on purpose, so the class could practice the technique of plotting points in a map. Then, a table with different UTM coordinates for each point was given to the students, who started to plot the points in the map (Figure 1). For that, the closest coordinate needs to be found in the grid. Then, considering the distance between grid labels, the point should be apart from the label at the necessary amount, which is an approximation.

Figure 1 - Use of table of coordinates to plot point in the map.

After having the points correctly plotted, it’s created a line between them to represent the path the group should follow. To keep track of this path, it’s necessary to have a known direction. For that, the compass was used to calculate the azimuth from/to each point. The first step to acquire the azimuth value is to correct the compass with the magnetic declination. Because Eau Claire has a declination close to zero, this procedure wasn't necessary in this case. Then, the travel-arrow in the compass is placed in parallel with the path. Holding the compass firmely, to avoid any movement, its housing is turned to be in parallel with the map north. (Figure 2) This is not extremely exact since you can only guarantee the precision by eye. One tactic is to use the lines inside the compass to compare to the grid lines.

Figure 2 - Calculating azimuth with the compass.

Having the values, a table with initial point, end point, azimuth and distance was created to keep organization of each path. However, only the first three fields were completed before the exercise. Instead of using the estimated distance each path would take – which could be done by having a ruler and calculating each path accordingly with the map scale – the amount of steps would be written there after the group walked each path.

In the field, to find the correct direction, it's necessary to turn the compass housing until the wanted value, and then turn yourself until the compass needle overlay with the compass housing "north". Then, the division of tasks within the group would help to increase the efficiency. I was responsible for holding the compass and guaranteeing the right direction by targeting a second person – Kent - who would go as far as he could and then adjust his position accordingly with my compass view. This model was chosen since the trees were almost indistinguishable one from another, so it would be hard to use it as a reference. After having the right direction using these two people, the third group mate – Joel – would walk counting steps to keep track of the distance already walked. When both arrive at the reference – Kent – the procedure starts all over again. Until by approximate calculations, it’s known that the course point was close. Following these procedures, it would be possible to find the necessary points.

Discussion

Some issues related with the precision of the measurements need some attention: in the plotting procedure as well as in the azimuth taking. In the first issue, as it was said, it's extremely rare that points would fall exactly in the intersection of the grid lines. Then, it's necessary to rely on approximations. At this moment, the interval of grid lines shows its importance. Of course that a low interval can clutter the map, but a big interval also compromise the precision in this task: the closer the grid lines are, the more precision you will have. Considering that, the choice of the group of dealing with 20 meters intervals can be considered consistent.

It's possible, even with large intervals, to have a high precision plotting. After calculating the relation between the coordinate labels and the coordinate you need to find, using a ruler, you would plot in the exact place it should be. However, this procedure is time demanding and such precision was not totally necessary with a 20 meter interval.

The precision is subject to the matter also when calculating the azimuth. Since there's a ruler in the compass, it's possible to place it exactly in the parallel with the path. However, the positioning of north can only be measured by the eye. As said before, the existence of north-south lines inside the compass were useful to be compared with the grid lines, which increased the precision of the measurement. Although it's still not completely accurate, the error shouldn't be larger than 5 degrees, what doesn't compromise the navigation in small distances as the ones this exercise deals with. It can be a huge problem, though, when dealing with enormous distances, as in some centuries ago with the marine development.

There's also another problem that didn't compromise the navigation only because the distances were small. The professor advised that, although he asked for an UTM grid, the correct way to navigate with a compass is using the Geographic Coordinate System (GCS). The reason for that is that UTM doesn't have a true north, since all the lines are equally apart from each other. In the real-world scenario, the closer to the poles, the closer the lines would be from each other. That's the way GCS grid lines would be (Figure 3).

Figure 3 - In the top a UTM grid for the United States; in the bottom, a GCS grid. The second has a curvature representing the true north of the map, while UTM doesn't.

It's necessary to have that because the compass relies on a true north, that is the one being showed by the needle. If your north is distorted by the map, that can compromise the accuracy of the measurements. Thankfully, since the area of interest is small, the curvature of the grid lines wouldn't be too high, so this specific navigation was not compromised.

Another matter that could have been improved is the organization of the table made after the point plotting and azimuth taking. As said before, three fields were completed, but the fourth that would have the distance was used as a reference to keep notes of how many steps the group gave.

It would be interesting if instead of having the distance after walking through it, the group had the calculated distance from the line. Using the scale, it would be possible to have it in meters, and then, using the pace count of Joel,  this could be converted to steps. Then, it would be easier to know how far the group were to the target point. Unfortunately, a ruler was not available at the time and the time was short to do this.

Another concern with the distance is that the pace count was obtained in a flat surface without snow. A totally different surface was faced in the field: steeps with about 30 cm of snow. The pace differs in this case, being usually smaller than in a regular surface. That means that the groups should walk more steps than the amount calculated.

Also in the subject of the adverse conditions, it was possible to notice that more preparation need to be made to go back to the field. It was challenging to walk over the deep snow in the steeps, and since the exercise was inside the woods, the dense presence of branches was constant and frequently impacted the pathway of the group. (Figure 4) Rarely it was possible to follow a straight line, so a lot of times, it was necessary to contour any obstacle and go back to the right direction.

Figure 4 - Impact of natural issues on the navigation.

Following all the procedures mentioned until now, it was possible to get from the initial point to the second point, even though the group location was a little east misplaced. This fact brought the idea that some error might have been done in the direction.

In the field, the group discussed about the reasons for that, and it was thought that it was necessary to target the azimuth in longer distances. The reason for that is that if a small error is done in a first measurement when targeting  it's carried on in all the next ones. Then, the less stops the group would made, the less error it would have.

With that in mind, the same procedure was made to find the second point. After walking the necessary distance, the group faced a deep ravine. Then, the map started to be analyzed to support the identification of the area. Unfortunately, a misinterpretation was made: by examining the contour lines, it looked like the point would be in the top of the ravine. (Figure 5) Then, one kept at the correct point, given by the compass, and the others would go look around to see if they would find the point. A long time passed doing that until Martin Goettl - one of the instructors - came and showed that the point was not on the top of the ravine, but on its bottom. 

Figure 5 - Location of point 3 on the contour lines.

After analyzing better the contour lines, it was possible to notice that this was correct and could have been avoided. Two lessons were learned with that: do not doubt your compass - errors might be made, but they would not put you that far of track, as long as you keep careful with it. And also to analyze more carefully the information in the map, it doesn't help to have a very detailed map if the reader doesn't take the necessary time to interpret it.

At this point, it was already more than 5:00 PM, so Martin decided to take the group to the next point while still wasn't dark, and then go back to avoid the darkness.

Conclusion

The main learning obtained in this exercise was about the compass reliability. It was disappointing not to accomplish the goal of the project, however, it was important to make this mistake and recognize it. That way, it's guaranteed that the idea behind the error is understood and it won't be committed again. The idea of misplacement by user lack of precision is right, however, it wouldn't cause big consequences, so it's always essential to trust the compass and don't doubt that much the location you'll be placed.

The contour lines were part of the map to support the area identification, and they would be really useful if the correct analysis was made. Another lesson comes with that: only put information in a map if the reader is able to understand and interpret it correctly, otherwise it can be more confusing than helpful. In the case of this project, the users were knowledgeable about the interpretation of contour lines, and the problem was that it was necessary to be more careful in the reading. However, it's important to understand this relativity of information provided in a map, depending on the target audience. If something is supposed to be released for the public, it might not be a good idea to insert technical concepts and features.

For last, it's important to recognize the positive sides of using a compass and map: even inside the woods, the precision is not compromised. Sometimes, when inside a really dense forest, a GPS unit can have an error too high or even not acquire satellites enough to display the coordinates. However, technology keeps developing more and more to avoid these problems. The downside is that to navigate with compass and a map is a very time demanding technique. Nowadays, the world requires efficiency at a high rate, so more practical solutions replace this method.

Navigation Part I - Preparation

Introduction

A huge part of geography is based in the old school techniques of navigation. In the past, the research for improvement in the navigation methods was the main reason for the development of geographic knowledge and exploration. Nowadays, for navigation, the technology of GPS is predominant for almost all the purposes. However, how it was already mentioned in earlier reports, it's essential to have the knowledge of the alternative ways, so you don't fully depend on this kind of technology, since it can fail on you.

Accordingly, this exercise consists in navigating at the priory using different methods: at first, a navigation map and a compass; in following week with a GPS, but no map; and for last, in the last week, with the GPS and a map. The goal is to find the advantages and disadvantages of the tools used and which ones are essential. However, before any of those navigations be done, it’s necessary to get prepared for it. Then, in this report the main elements to be prepared to go on the field will be explored, by elaborating the necessary material.

Methodology

For the first week of navigation, with compass and a navigation map, it’s necessary first to produce the actual navigation map with the elements necessary, and since there won’t be any device to calculate the distance, the measurement of the personal size of each step is made.

The method to find the actual size of each step is by creating a known distance line – in this case of 100 meters – and walk by it for multiple times counting steps, until it doesn't have reasonable discrepancy.  To measure how much was 100 meters, the laser device was used: one student (Amy) was targeting and another student (Me) was moving and being targeted until it reached the necessary distance. (Figure 1) Once reached, the spots were marked with snow, so the students would know where to start and finish. After having the result of the number of steps, a simple calculation will result in the size of the step, which in this case was 1.45 meters per step.

Figure 1 - Right: Amy using the laser device to target the distance of 100m. The snow on the floor worked as the start point for the pace count. Left: The path of 100 meters while I was being targeted by the laser to guarantee a precise measurement.

In the production of the map, the location where the navigation will be made had to be analyzed. Different elements can work as a reference depending on the place you are. If it’s an urban area, maybe building and streets are important reference features. However, the priory is located in an open field, with basically only vegetation around and very few buildings. Thus, the reference in this case has to be the natural features, as vegetation types and elevation.

After identifying the important elements for the map, the related data have to be gathered together. For that, it’s important to evaluate the different sources one can access data. For convenience, the main data was available for the whole class. However, to find data related to elevation and vegetation, a good source would be the USGS, within The National Map Viewer. For this map the Digital Elevation Model was obtained from USGS, however, the two feet contours for elevation were obtained by UWEC survey, at the time the university bought the area. The imagery was obtained by the Wisconsin Regional Orthophotography Consortium 2010 (WROC 2010).

With the data gathered in ArcMap, the challenge is to insert the most of useful information as well as not making the map very polluted and busy. For that, some cartography techniques like transparency and change of colors were used to maintain most of information, but emphasizing only the ones that were essential. Since the work was being done as a group, each one started its own map (Figure 2), but after seeing the progress of each, the whole group focused in one of the maps, giving suggestions and improvements.

Figure 2 - Individual Map

The purpose of the map is the main element that has to be remembered while working with different priorities in the cartography. Since the objective was for navigation in a certain portion of the map (Area of Interest in the Figure 2), the main references were prioritized, while areas outside this area could have other map elements like north arrow, scale and others.


Discussion

In this project was possible to experience how troubleshooting enforces knowledge of a given subject, in this case, projections. One of the most important features – the 2 feet line contour – didn’t have the projection information. In Arc Map, by adding this data to your session, the on-the-fly projection will automatically put the feature in the data frame projection. However, it will just work if the data frame projection is the same as the one the feature was created. Otherwise, the coordinates won’t make sense and the feature will be placed far off.

With this kind of issue, it’s also common to make confusion with two different tools inside Arc Toolbox: Define Projection and Project. The first will simply label the feature with a projection, overwriting the last one, but it won’t change its coordinates. The second changes the coordinates, using complex math, creating a new feature, projected. In this case, one could think that it was necessary to run the project tool, but that wouldn’t be possible since the feature is not even labeled yet.

Thus, it was necessary to analyze the extent of the data, going to its properties, in the source tab. There, you would have the extent numbers, however, without its units (Figure 3). By looking at that, it’s easy to detect if it’s a projected or geographic coordinate system because of the units – big numbers for projected (meters or feet) and small numbers with a lot of decimals for geographic (degrees).

Figure 3 - When dealing with a undefined coordinate system, it's possible to interpret the extent coordinates and try to find the correct projection.

Then, it was known that it was a projected coordinate system, and because of the purpose of the map, that this feature was located in Eau Claire. Considering the main coordinate systems, there were some options: UTM, Wisconsin State System and Wisconsin State Plane System – Central. The first thought was about UTM, but in this system, the Y coordinate in the north hemisphere means the actual distance of the place from the equator. Y coordinates about 476 kilometers didn’t seem right for an Eau Claire location. 


Since the feature has an undefined coordinate system, it’s not a problem to overwrite the label over and over to make tests using the Define Projection tool. Then it would be fine to test the UTM coordinate system, even though it seemed odd. However, the data format was DWG, so the Define Projection tool couldn’t simply be used on Arc Toolbox. It was necessary to go on Arc Catalog and define the projection for the entire dataset. Once done, the results showed that UTM was really not the right projection.

Figure 4 - In the same coordinate system, there's multiple variations of units and datums.

By looking again to the extent, it sounded reasonable for the Wisconsin State System. However, there’s a big list of Wisconsin State Systems, depending on the datum or units (Figure 4). As mentioned before, there’s no problem in testing different projections, so the first test was made with “NAD 1927 Wisconsin TM (Meters)”. Finally the feature was placed at least closer than Eau Claire, however, it was still too far off the Area of Interest. Even if a reference as the Area of Interest was not available, it would be possible to perceive the misplacement of this feature by interpreting the contour lines along the landscape in the satellite image: they don’t fit at all. (Figure 5)

Figure 5 - The feature was placed far to north-east from the Area of Interest. Plus, in the zoom of the contour lines, it's possible to notice how they didn't fit with the landscape of the satellite image.

That’s where the knowledge not only about coordinate systems and projections, but also about datums are useful. Different datums (NAD 1927, NAD 1983, WGS84) don’t match each other, even if you have the same projection and coordinate system. Hence, even setting up everything in the right properties (coordinate system, projection and units) won’t help if the wrong datum is chosen: the features will be far off, as it happened in this project. The right datum in this case was NAD 1983, which was discovered in the next test: the feature fit the landscape and fell inside the Area of Interest.

Furthermore, after dealing with the data issues, it was interesting and challenging to deal with a considerable high amount of information in the map, without making it cluttered and busy. The contour lines could easily be less emphasized by adding some transparency to it, or changing its color to a lighter gray.

For the grid, it was a little more complicated than that. The goal would be to plot point on it, so the finer the interval, the more precise the plotting would be. However, the lines of a small interval could almost inhibit the readability of the actual features in the map. Some intervals were firstly tested and the decision of keeping with a 20 meter interval came after editing it in a way it would lose emphasis in the map. That way, the lines were changed from continuous lines to dotted lines. To avoid confusion with the contour line, the color was changed.

Conclusion

This exercise exposed two faces of map-making: the strict rules of data sources and the flexibility of cartography. It was important to reinforce the dynamic of geography and how everything needs to be thought in its different purpose and background.

When dealing with coordinate systems, projections, datums and units; you have to be very exact and certain of the information to keep data reliability and accuracy. Technology can often support this task not to be so exhaustive, as seen by the use of on-the-fly projection, what usually works to match two different features in the same place, even though one might not have a defined projection. However, this exercise was an example where this tactic didn’t work. Thus, when obtaining data, it’s crucial that you always have the necessary information to deal with it. Unfortunately, it’s not common to find all the necessary details in the metadata, so it’s essential to keep track of the data sources and always get the necessary information about it.

However, a more flexible task was also experienced by using the cartography to manage the map-making. In this area of geography, there’s no such rigorous since there’s no right and wrongs, but a number of possibilities that can meet your goals of presenting data. It doesn’t  mean that anything that is done will be correct, it’s always fundamental to focus on the purpose of the map and test different forms of dealing with different priorities. That can be challenging, exactly because there’s not only one right answer and it’s commonly a trade-off.

Summarizing, the results of the exercise were satisfactory, but mainly, dealing with these challenges was a great experience to improve and reinforce our geographic knowledge.