The Ultimate Guide To Getting Topo And Terrin

Topographical maps are an incredibly useful tool for planning construction projects, understanding the landscape, and navigating. They can help you visualise the terrain of an area, showing the elevation, slope, and shape of the land, as well as the location of water features. The closer the contour lines, the better you can understand the nature of the slope. Topographical maps can be purchased from specialist companies or created yourself using tools like Google Earth and Google Elevation API. The US Geological Survey (USGS) also offers topographic maps of the US, and there are online resources for continually updated map data.

Using Google Earth and Contour Map Creator

Google Earth and Contour Map Creator are powerful tools that can be used together to generate topographic maps, also known as topo maps, to understand the terrain of a specific location. Here is a step-by-step guide on how to use these tools effectively:

Step 1: Accessing Contour Map Creator

Start by opening the Contour Map Creator website (http://contourmapcreator.urgr8.ch/) in your browser. This website provides a free web application that enables you to generate contour lines for your desired location with just a few clicks.

Step 2: Locating Your Area of Interest

Once the website is loaded, zoom in on your area of interest, such as your property or a specific geographic location. You can use the search bar to find the location and then centre the map with your chosen area in the middle. It is important to note that you should not zoom in too closely, as you also want to understand the overall topography surrounding the area.

Step 3: Defining the Sampling Area

To generate contour lines, you need to define a sampling area by drawing a rectangle on the map. You can do this by adding two pins to the map, placing one pin in the northwest corner and the other in the southeast corner of the area you want to analyse.

Step 4: Adjusting Plot Options and Generating a Contour Map

Before generating the contour map, you can adjust the plot options to customise the resolution of your map. Adjust the level interval option to determine the distance between contour lines. For example, setting it to 5m/15ft will result in contour lines appearing every 5 metres or 15 feet.

After adjusting the plot options, click the "Get Data" button, and the Contour Map Creator will generate a contour map for your selected area.

Step 5: Importing the Contour Map into Google Earth

To enhance your analysis, you can import the generated contour map into Google Earth. Scroll down on the Contour Map Creator website and press "Download KML file". Then, locate the downloaded file in your folder and open it in Google Earth.

Google Earth will automatically zoom in on your selected area, and you will see contour lines overlaid on top of the satellite image. If Google Earth does not automatically display the contours, you may need to enable the newly imported "Contours" kmz file in the sidebar under the "Places" bar.

Benefits of Using Google Earth and Contour Map Creator

Using these tools together provides a straightforward and cost-effective method for generating topographic maps. While the accuracy of the Contour Map Creator may vary depending on the location, it still offers a valuable starting point for understanding the terrain.

Google Earth, with its satellite imagery and terrain view, complements the contour map by providing a more detailed visualisation of the area. Additionally, Google Earth offers various tools that can assist in designing and planning based on the topographic information.

By utilising both Google Earth and the Contour Map Creator, you can efficiently generate the topographic data needed for informed decision-making in projects ranging from permaculture design to construction planning.

The US Geological Survey (USGS)

The USGS offers a variety of topographic map products, including the latest US Topo series, which is a latest-generation topographic map with over 3 million downloadable files from 2009 to the present. These maps are available on the USGS website and can be downloaded and printed. However, printed maps may have limited trail information and lack in-the-field verification.

Another option is to use the topoView tool, which provides access to both current and historical maps. This interface is part of the National Geologic Map Database project (NGMDB) and supports the topographic mapping program managed by the USGS National Geospatial Program (NGP). With topoView, you can explore older maps of each area, which is especially useful for understanding historical changes, such as the names of natural and cultural features.

Additionally, the USGS offers pre-2009 7.5-minute maps, which are considered the standard for topographic mapping in the US. These maps are widely recognised as the most detailed available and serve as the foundation for other topographic maps in the country.

For those seeking custom maps, the USGS also provides the ability to design your own true-to-scale, custom-centred map or aerial photo. You can include military, UTM, and Lat/Long grids and centre any place in the US or Canada.

With the USGS's comprehensive offerings, you can easily obtain the topographic maps and tools necessary for understanding and planning your property or area of interest.

Using GIS tools

GIS tools are a great way to get topo and terrain data.

One option is to use QGIS, which has good terrain processing capabilities built-in. You can download the GMTED2010 dataset from the USGS Earthexplorer site. This is a global terrain dataset that is the newer version of the GTOPO30 dataset. Once you have downloaded the zip file, open it in QGIS and you will see the terrain data rendered in the QGIS canvas. Each pixel in the terrain raster represents the average elevation at that location, with dark pixels representing low altitude and lighter pixels representing high altitude.

Another option is to use ArcGIS, which can be used to make a simple topographic map. You will need a digital elevation model such as ASTER GDEM v.2 or SRTM. This will be your first layer. Next, you need to calculate hillshade by selecting "Surface analysis" and clicking on "Hillshade" in the Spatial Analyst tool. You can then adjust the settings to improve the contrast and make the image clearer.

You can also use GIS tools to create a topographic map in Google Earth. First, locate your property on the Contour Map Creator website and draw a sampling area by marking a rectangle with two pins. Adjust the plot options and put in the level interval, which determines the resolution of your contour map. Click the 'Get Data' button and the app will generate a contour map for you. You can then import this into Google Earth, which will automatically zoom in on your property and overlay contour lines on top of a satellite photo background.

Using a compass

Choosing the Right Compass

Firstly, it's important to choose a suitable compass with the right features. A good compass should have:

• A clear baseplate, allowing you to see the map underneath.
• A sighting mirror, for sighting objects at eye level.
• A rotating bezel marked with 360 degrees, often called an azimuth ring.
• Meridian lines, used for map navigation.
• A declination adjustment and arrow to correct the difference between magnetic and true north.

Understanding Basic Compass Anatomy

Before using a compass, it's crucial to understand its basic anatomy. A typical outdoor baseplate compass consists of:

• A compass housing (rotatable dial) attached to the baseplate.
• A magnetic needle housed within the compass housing, often with a red end pointing to the north.
• A rotating bezel with bearing marks, also known as an azimuth rim.
• An orienting arrow, also called an orienteering arrow, with a red end indicating north.
• Orienting lines, also referred to as meridian or orienteering lines, printed on the base of the compass housing.
• A direction-of-travel arrow on the baseplate, usually parallel to the longest edge.
• Rulers or scales along the edge of the baseplate for measuring distances on maps.

Taking and Following Bearings

A bearing is a direction relative to your current position. To take a bearing on a distant object, such as a mountain or a landmark, follow these steps:

• Hold the compass away from your body, pointing the direction-of-travel arrow on the baseplate at the object.
• Rotate the compass housing until the red end of the needle is directly over the red orienting arrow.
• Read the bearing number on the compass housing that lines up with the direction-of-travel arrow.

To follow a specific bearing, such as navigating to a campsite or a treasure cave, follow these steps:

• Dial the bearing on your compass.
• Set the sight mirror at a ~45-degree angle, hold it level, and bring it to eye level.
• Close one eye and turn your body until the north needle is within the declination arrow or box.
• Identify an object on that heading, such as a tree or a peak, and head towards it.

Adjusting for Declination

It's important to understand the difference between true north and magnetic north. True north is the fixed point towards which your map is oriented, while the magnet in your compass needle points to magnetic north, which changes slightly every year. To navigate accurately, you must adjust for declination, the difference between these two norths.

Find the declination value for your trip area, which can be found on topo maps or by consulting the National Oceanic and Atmospheric Administration (NOAA). Then, follow the instructions provided with your compass to set the declination. Once set, you won't need to adjust it again unless you travel to a faraway place.

To use a compass with a map effectively, you can employ techniques such as orienting your map, taking bearings from the map, and following bearings in the field.

Orienting Your Map

Place your compass on the map with the direction-of-travel arrow pointing towards the top of the map. Rotate the bezel so that north (N) is lined up with the direction-of-travel arrow. Slide the baseplate to align it with the edge of your map. Finally, rotate your body until the end of the magnetic needle is within the outline of the orienting arrow. Now your map is oriented correctly.

Taking a Bearing from a Map

To take a bearing from a map, follow these steps:

• Set your compass on the map so that the straight side of the baseplate lines up between your current position and your desired destination.
• Ensure the direction-of-travel arrow is pointing in the general direction of your destination.
• Rotate the bezel until the orienting lines on the compass align with the north-south grid lines or the left and right edges of your map.
• Read the bearing from the index line.

Following a Bearing in the Field

To follow a bearing in the real world, follow these steps:

• Hold the compass with the direction-of-travel arrow pointing away from you.
• Rotate your body until the magnetized needle is inside the orienting arrow.
• Now, the direction-of-travel arrow is facing the bearing you want to follow.

Triangulation

If you're unsure of your current position, triangulation can help. Identify at least two prominent landmarks that you can also locate on your map. Take bearings from these landmarks and transfer them to your map by drawing faint lines. The point where these lines converge is your current location.

Additional Tips

• Practice your map-reading and navigation skills before embarking on your trip.
• Always carry a recent map of the area you'll be travelling through.
• Plan your route in advance and share it with someone you trust.
• Don't solely rely on modern technology like GPS, as batteries can die and devices can malfunction.
• Consider taking a class or course to master compass and map navigation skills.

Understanding contour lines

Contour lines are a key feature of topographic maps, which are essential for understanding the terrain of an area. These lines connect points of equal elevation, and by observing their spacing and arrangement, you can visualise the shape and steepness of the land.

Contour lines never intersect; instead, they form a series of curves that indicate the elevation of the land relative to a given level, such as mean sea level. When contour lines are close together, it means that the elevation is changing rapidly over a short distance, indicating a steep slope. Conversely, when the lines are spaced further apart, the elevation changes slowly, and the terrain is relatively flat or gently sloped.

Contour lines can form various patterns, each indicating a different aspect of the terrain. For example, roughly concentric circles usually indicate a peak, while the areas between peaks often represent passes. Sharp-pointed "V" shapes typically indicate stream valleys, with the drainage channel running through the point of the "V". Closed loops are usually uphill on the inside and downhill on the outside, with the innermost loop representing the highest area. On the other hand, rounded contours suggest flatter or wider drainage or spur areas. Contour lines that merge indicate a cliff, while contour lines that enclose small areas on ridge tops suggest pointed ridges.

Every fifth contour line is typically thicker or bolder, known as an index contour line, and it shows the exact elevation at some point along the line. The change in elevation between successive contour lines is called the contour interval, and this value is usually provided in the map's legend. The contour interval should remain consistent throughout a single map, and it helps to determine the hilliness of the terrain when calculated as a ratio against the map scale.

Topographic maps are incredibly useful for understanding the land and can be used as a base for designing or planning activities in a specific area. They can help identify potential flooding areas, steep slopes, rock outcrops, soil depth, and more.

Frequently asked questions