We've found a small, promising area and have decided to look at mapping it. Follow along as we produce an orienteering map! We expect this project will take about 40 hours of work spread over a month-long period. We'll divide the job up into roughly ten four-hour "days". If you like, see if you can replicate these steps for your own local project.
About the San Juan Overlook
Day 1 Gearing Up
Day 2 Area Survey
Day 3 Planning and Prep | Contours
Day 4 Armchair Mapping
Day 5 Collecting Field Data
Day 6 Field Cycle 2
Day 7 Field Cycle 3
Day 8 Field Cycle 4
Day 9 Field Cycle 5
Day 10 Field Cycle 6
Have you got questions, comments, advice, or recommendations? Great! Drop us a message, or better yet, post on the skypilots facebook group. Your comments will very likely help other mappers who might encounter the same issues.
The San Juan Overlook is a rarely visited corner of Ridgway State Park in Ouray County, Colorado. We're interested in about 200 acres of wooded hills east of Highway 550. We think it would be a great area to set some beginner and intermediate courses for informal club training and practice sessions, starting with this one on October, 23, 2021.
About two thirds of the area is dominated by readily-passable piñon-juniper forest. The rest is open ground, a mixture of sagebrush and grassland. The only troublesome plants are tiny cacti; we'll try to identify the worst patches and plan courses around them.
The topography is steep enough to be readily discernable, but gentler than most other public lands in our county. There's a nice little trail loop, a road or two, and an assortment of other linear features. We're also aware of several interesting cliff bands and a scattering of other rock features.
Let’s make sure that we have all the tools we’ll need. Then we’ll start a crash course in using our primary software.
We've put together a Crash Course for Open Orienteering Mapper so you can quickly get up to speed with our main software. You don't have to get through the entire crash in one day—just come back to it as time allows.
On Day 2, we'll conduct an Area Survey.
A prudent mapper will strongly consider an area survey prior to actual mapping. Through a combination of research and site visits, a survey determines whether mapping the area is feasible, discovers what resources are available, sets boundaries for the project, and decides the map scale, the contour interval, and which features will be mapped.
Yes, you could skip all that and just start mapping. But you’ll probably make some missteps—maybe some serious enough to require throwing out a good chunk of work.
Maybe that’s an inevitable risk for a beginner? The truth is, it’s difficult to perform a survey properly unless you already have some experience mapping, because you don’t really know everything to look out for.
We'll try to muddle through anyway.
Based on our prior visits, we think the area is both mappable and suitable for orienteering:
However, there are no water or restroom facilities, so it's probably not the best location for a large, formal event.
A good source of digital elevation data is critical for drawing contour lines. For the United States, the 3DEP LidarExplorer is very handy for determining what’s available.
Clickthe Draw Area of Interest icon ②
CTRL-Dragdiagonally ③ to form a quick-and-dirty rectangle (erring on the side of overly large)
We get nothing for Lidar ⑤. That's a shame because it’s usually the best possible data source.
Looking at DEMs (Digital Elevation Models) ⑥, the best resolution available is the ⅓ arc-second series. This series is available throughout the contiguous 48 states and provides one data point for (roughly) every 10 lateral meters on the ground. The height data is accurate to a meter or so.
Though the ⅓ arc-second series ① isn’t ideal, it should be good enough to produce some tentative contours. Some amount of manual correction will be needed based on site visits, but we should be able to produce a decent map.
In a way, this is good! Working with Lidar data is far trickier and probably deserves an entire tutorial of its own. And since the ⅓ arc-second series is available in most of the United States, there’s a good chance you’ll be able to exactly replicate these steps for your own project too.
To actually grab the data,
Click on the Download list icon ② and open the resulting text file with Notepad. We see two different web addresses. Both are for the same geographical area (one degree of latitude by one degree of longitude) but one has a newer date. We’ll plug that one into a browser to download our dataset. Note that the file is in TIFF format, easy for QGIS to digest.
P.S.: For an alternate source of digital elevation data, try the national map.
I was also able to get hold of parcel data from the county. This not only helps define our project boundaries, but also reveals who owns the neighboring lands and confirms that there aren’t any private in-holdings that could raise problems. Though convenient, parcel data isn’t necessarily a requirement for producing a good map. There are plenty of other ways you might decide to set your project boundaries.
Here’s our basic strategy for setting the project boundaries:
Even if a competitor never sets foot outside of the parcel of interest, the buffer area is needed to provide anyone near the property boundary with enough context to navigate.
Our parcel data is in KMZ format, therefore meant for Google Earth, so we’ll go ahead and use that.
Clickthe Projects icon on the toolbar on the left edge of the screen
Import KML file from computer. Our KMZ file is just a zipped version of a KML, so Google Earth will understand it.
It's a moderately large file, so it takes a minute. Once it loads,
Drag the map to the correct area and zoom in (pictured).
We’re interested in the oddly-shaped purple area southeast of the highway—except for the southwestern blob. It only connects to the main area by a long, skinny neck, so it's sort of lousy for orienteering.
To proceed, we’ll need to create a separate Google Earth project. Why?
Click the Projects icon ① to open the Projects panel (assuming it's not already open), then
New Project… ②, then
Create KML file. We'll name the new project
San Juan Overlook Project Bounds.
Unfortunately, our parcel lines disappear! That’s because we’re only viewing a single project at the moment—the new one.
Click the Back button on the Projects panel (not on the browser as a whole) to view both projects at once. We're finally poised to start drawing something.
Clickthe Draw line or shape tool ①
Clicka series of points tracing the applicable portion of the parcel of interest ②
parcel of interest)
Once it's saved,
Click the new shape (either on the map or the Projects panel). Then
Click the Pencil tool to change any desired properties of the object (like the line's color or thickness).
And since we no longer need to see a bunch of irrelevant parcel lines, let's change the view to just the project we're working on. On the Projects panel,
San Juan Overlook Project Bounds ③.
To draw the buffer:
We're done with the boundaries! To export them:
⋮(the three vertical dots to the upper right of the Projects panel)
Export as KML file(saves to your default folder, such as Downloads)
Let's make a note of the bounding rectangle that encompasses the area to be mapped. The bounding rectangle:
Hover over each of the extremes in turn and make a note of what's displayed in the lower right corner (you may need to go into : Settings to format what's displayed as decimal values). Round to more extreme values, and be sure to record them in the order listed. In our case, we get
-107.7219, -107.7376, 38.1977, 38.2179. More precision than that isn’t required.
With the resources at hand, we expect to conform to the international standard: 1:15,000 scale with a contour interval of 5m. We’ll print at 50% enlargement (so 1:10,000) to improve readability, especially for the beginner courses. The final printed area will be about 8.7 inches tall and 5.5 inches wide, easily fitting on a normal sheet of paper with some room on the margins for a legend and clue sheet.
International standards set minimum dimensions for certain features. For example, 109 Small knoll requires at least 1m of prominence on all sides. If it's smaller than that, it doesn't get mapped. But for several symbols, we must make specific decisions appropriate to the terrain.
We'll need threshold heights for 204 Boulder and 205 Large boulder. Scattered boulders occur throughout the area, but most of them are fairly small. Based on our site visits (and past experience), our tentative plan is to map every boulder that exceeds 0.5m from at least one side. Anything taller than 2m will be considered a large boulder. We think this will work out, but if the map turns out too cluttered, we’ll simply increase the thresholds as needed and then throw out any boulders that are too small. To make this work, we’ll need to collect height data for every candidate boulder.
There are several symbols whose meaning can vary from map to map. For this map, here's the plan:
One question we don't yet have an answer to: how to handle 420 Prominent fallen tree? The usual threshold height-off-the-ground is 2m, but we'll have to verify how well that will work for the area the next time we make a site visit. Many fallen trees occur in the area. Set the value too low, and the map will be very cluttered and hard to read. Set the value too high, and runners may draw incorrect inferences from the map and suffer consequences as a result.
If there is no single value that works well, we should consider omitting the symbol entirely, and just represent any denser areas of fallen trees with standard vegetation symbols (slow run, walk, fight).
Contours make Day 3 a big one!
We'll get our OOM map file as ready as possible without actually drawing anything printable quite yet.
To tie the map to real-world coordinates, we need a map reference point. How do we choose a good one?
The best spot we’ve got seems to be the actual summit of the San Juan Overlook. It’s a bit of a compromise.
In Google Earth, hover over the spot and make a note of the coordinates. Rounding a bit, we get 38.20507, -107.72646.
Launch OOM and create a new file (
CTRL-N), using 1:15,000 for the map scale and our club symbol set for the symbol set.
This is a bit of technical magic—you don’t really need to have much understanding of it at this point. Just be aware that if you screw this up, your map could go absolutely haywire—possibly deformed or unrenderable—and you’ll probably have no idea why.
Map… Georeferencing…dialog ①. In the Map coordinate reference system section, select
UTMfrom the drop down ②. For most areas, UTM is a good choice because it is pretty good at preserving shapes, compass bearings, and linear distances—at least across the scales that are commonly encountered while orienteering.
Calculate④ to set your UTM Zone (for our part of Colorado, that’s 13 N).
Lookupbutton ⑤ will take you to a website with current information for your map reference point. If the declination is in the east direction, treat that as a positive number. If west, negative. Plug the proper value (9.03 in our case) into the georeferencing dialog ⑥. The grivation will automatically calculate. To finish the dialog,
The map is now aligned with magnetic north, which makes reading it a lot easier for both beginners and experienced orienteers alike. No need to fuss with declination!
Map parts are sort of like layers or folders—a way to organize the many objects that will populate your map. To create one:
Map… Add new part…①
Note that a newly created part is inserted just below the one that is currently selected in the drop-down part selector ②. Keep creating them, because we'll need a bunch:
104 earth and rock,
501 roads and paths,
510 other built,
901 frame. When you're done, select the
default part from the drop-down and then apply
Map… Remove current part.
Newly created or imported objects will land and thereafter reside in whatever map part is currently active. They’ll only be accessible or manipulable when that part is chosen on the part selector drop-down menu. Map parts help protect features that you’re not actively working on from unintended edits. Also, if you’re trying to
Click on a particular boulder, it’s a lot easier if there’s no way you could accidentally target any of the several nearby contours, vegetation markings, footpaths, buildings, and so on.
The key is to make sure that you have the part selector pointed at an appropriate part before creating or importing any objects. If you’re comfortable with it, very simple datasets can often be safely imported directly to their final home. But if you’re importing anything that will require complex processing, it’s often better to let it camp in
000 temp for a while. Move finished products (or otherwise wayward or misfiled objects) to the proper part with the
Map… Move selected objects to… command. If you’re working on the
000 temp map part, you know you’re done when
CTRL-A fails to locate any more objects.
Let's grab what we drew on Day 2 and port it to OOM:
801 helpermap part ①
File… Import…command ②
San Juan Overlook Project BoundsKML file ③ and
Assign the proper symbol to each newly imported object:
Clickthe outermost object ② to select it
Clickthe tile for 814 Project bounds ③
Repeat the process to assign symbol 814.1 Course planning area ④ to the innermost object ⑤.
Like the other symbols in the helper family, these objects are non-printing. And if any symbol (not just a helper) is cluttering your view of the map, just toggle its visibility:
Right-Click its tile on the symbol palette, then
Hide objects with this symbol.
Grid lines help us organize our work, set priorities, and track our progress. They also let us break a big job into smaller, more manageable chunks. To configure grid lines:
Clickthe drop-down arrow ① on the right side of the Show grid tool
Align with magnetic north④
Each grid square needs a unique reference:
801 helpermap part ①
Clickon the perimeter of the map ④ and type an appropriate label (such as
Be sure to Save your file (
CTRL-S)! We'll name ours
San Juan Overlook.omap.
It’s sort of a shame that contours are the first printable objects we get to draw, because they are by far the hardest. But nailing this step early in the mapmaking process is key to preventing a truckload of potential trouble further down the line.
Don’t put yourself in a position where you’ve already mapped hundreds of features, only to find out that your coordinate reference system is broken when you try to overlay contours on top of them!
The result looks cool, but there are a couple issues—one cosmetic and harmless, the other fairly serious despite being nearly invisible.
The cosmetic issue is that... Well, the shape looks wrong. We know that the geographical extent of our source file is one degree of latitude by one degree of longitude. We also know that on an actual globe, those things should be rather different sizes since we’re not really near the equator. Yet our map appears square.
Don’t worry. It’s merely an artifact of the coordinate reference system currently used to display our source file—NAD83 EPSG:4269—as shown in the lower right corner of the window. We can safely ignore the apparent distortion, because it will automatically be corrected when we port our contours to OOM, which we’ve already configured to use a more appropriate CRS.
Just be aware that the contours as viewed in OOM will appear laterally squashed compared to those we’ll soon be extracting in QGIS, and that’s perfectly OK and expected.
The second, more serious issue is that the map extent is way, way too large. A degree by a degree? That’s so large that we’re risking a system crash if we don’t limit it beforehand.
Here's how to solve the size issue:
Raster… Extraction… Clip Raster by Extent…①
-107.7219, -107.7376, 38.1977, 38.2179②
This operation creates a new, smaller, temporary layer without altering the original one. You can tell it’s temporary because of the Eraser icon next to the layer name on the Layer panel.
With the new clipped layer selected,
Click the Zoom to Layer tool ④ to zoom way, way in.
With the clipped layer still selected ①:
Raster… Extraction… Contour…②
Depending on the size of our area, creating the temporary contour layer might take a considerable amount of time. Our area is tiny, so it only takes an instant.
To save our contour layer as a stand-alone file,
Click on the little Eraser icon to the right of the layer ⑦. Change the format to
ESRI Shapefile (which preserves not only coordinates, but also database attributes such as the numerical value of each contour line in meters). Put in a suitable filename (
Finally, Save (
CTRL-S) the QGIS project as a whole (we're happy throwing away the other temporary layer, which is just a clipped version of the digital elevation data).
101 contoursmap part ①
File… Import…command ②
.shpstand-alone file that we created in the previous section ③
For a large file, the import could take a while. This is our moment of truth!
Click-ing the Show whole map tool)
Right-Clicksymbol 814 Project bounds and make sure that the Hide objects with this symbol option is de-selected. Do the contours align as you would expect with the Project Bounds, bearing in mind that the bounds are sort of a rough approximation in the first place?
If you answered Yes to all the above, congratulations! Your contours have passed some basic tests (maybe we'll talk about more rigorous testing in an addendum, but that's something that's a lot more important for a larger map).
This is a good point to save your file!
101 contoursmap part ①
CTRL-Ato select all objects on the part
Clickthe tile for symbol 101 Contour ②
CTRL-Gto switch all of the generic purple lines to brown contour symbols
nkey to convert them to smooth bezier curves
The last bit will take a noticeable amount of time—a lot of time if your file is large. Too large, and the system could crash. This step right here is why we severely clipped the area in QGIS.
All good? Definitely
Depending on the granularity of your source data, you might find some noisy closed contours, or little loops that are smaller than the minimum permissible size. These will often look like small brown specks. For the most part, you should just delete these manually (select them with the Edit objects tool and then hit
Delete). However, you might want to make a note to field these locations to look for small knolls or depressions (which are represented by their own special symbols).
We want every fifth contour to be a thicker 102 Index contour. Since our area is fairly small, let’s just do them manually, one at a time:
Clickone of the contours more-or-less at random ②
Click-ing the same spot and the program will cycle through several different nearby possibilities. Getting the precise object you want will be fairly important rather soon, so keep this tip in mind.
CTRL-Shift-6to pull up any data associated with the selected object on the Tag Editor ③
ELEVvalue ④ that's a multiple of five, then we've found one that we want to change to an index contour (and if not, keep
Click-ing until you find one that is)
We need to carefully consider any contours that are touching, or that violate the minimum gap rule (closer than 0.15 mm to one another) ① ②.
Most commonly, it’s because there is a cliff ①, earth bank, gully, rock monolith, or similar feature in that location. That’s fine, because the appropriate symbol will eventually occlude the offending contours, or else we’ll end up trimming the offending contours away.
If a site visit (or logic ②) reveals that no such feature is present, we’ll need to manually adjust some of the contours so that they conform with the minimum gap rule:
Clickthe contour to be adjusted with the Edit objects tool
Dragone of its square blue handles away from the neighboring contour
If any of your contours represent depressions (which you can verify by examining the
ELEV attribute as shown on the Tag Editor), you'll need to manually give them some little tags pointing downhill:
Dragin a circular motion to rotate the slope line until it is perpendicular to the contour, then
Clickthe Edit objects tool to exit rotation mode
Dragthe slope line's square blue handle to fine-tune its position to make sure it is connected to the actual contour
Data collected in the field might reveal that a contour needs to be adjusted. Several methods are possible:
We're likely to see some of these corrections in action as we get deeper into the tutorial.
With a session of Armchair Mapping, we get to start populating the map with a greater variety of objects.
There are two basic methods for armchair mapping:
In the end, it comes down a matter of preference. For this tutorial, we'll take the second approach. Though the first approach sounds simple, it can be quite tricky to align a template properly if it isn't already georeferenced, and you need quite a lot of imagery if you want to cover the entire area with the highest possible resolution.
Initially, we’ll focus on big features that are obvious from the sky, like highways, bodies of water, dirt roads, large buildings, and the like. Later we can look for subtler things. One thing that we won’t worry about yet—at all—is vegetation mapping. That’s something that’s better handled after we’ve made a few site visits and have laid down plenty of landmarks on the map that are less subjective in nature.
We'll need a third Google Earth project for tracing features:
Create KML file, then name the project (
San Juan Overlook Features)
Let's start with the simplest case—something that can be represented with a single line symbol, like a dirt road. We'll pick the one leading east from US 550, past the parking area, and off the eastern map edge:
Clickthe Draw line or shape tool ②
Clicka series of points tracing the road ③
Clickjust inside the paved part of the highway, thereby leveraging the color priority scheme to ensure that once the highway is drawn, the intersection will appear clean and gapless
Clicksat the sharper bends ④
Clickjust outside the Project Area
Enterto save the line ⑤
Alkali Creek Road), make certain that the line is being saved to the correct Project (
San Juan Overlook Features), and
San Juan Overlook FeaturesProject,
⋮(the three vertical dots to the upper right of the Projects panel), then
Export XML file
501 roads and pathsin this case), give the
File... Import...command, select the
San Juan Overlook FeaturesKML file (or the most recent instance, if there are several instances),
Open, and if asked, accept the default symbol assignment (
nkey to change the angular line to bezier curves (if appropriate, certainly true for this dirt road), then use
CTRL-Gto switch the line to an appropriate symbol (in this case, 504 Vehicle track)
Hoverover it's name, then
⋮ Delete), leaving a clean slate for whatever drawing task we want to tackle next
Thats the basic method. Whether it's with points, lines, or areas—blue, brown, black, white, yellow, green, or purple—or a mixture of any of the above: draw and port. It's amazing how much you can get done that way! However, there are some situations that call for more specialized techniques.
It would be nice if we could draw US 550 as soon as possible. It’s not actually within the parcel of interest, but it’s well within the project area and it’s critical for navigation. It’s very large and very visible from the sky and it will serve as one of the fundamental landmarks for our map. But the task of drawing it is more complex.
Within our project area, the highway varies in width from two to four lanes. If we zoom in a bit with Google Earth and use the Measure distance and area tool, we get widths ranging from about 18 to 29 meters. This presents an interesting challenge to draw and we’ll need to think about it a bit.
Since the road is much wider than 5 m, it would seemingly call for one of the wide road symbols (in the 502 family). However, the specification for 502 says that
the width should be drawn to scale, but not smaller than the minimum width, and none of the 502 family of preconfigured symbols is wide enough! The widest is 502.2 Road with two carriageways (meaning a divided highway). It weighs in at just 1.02 mm on the map, or only 15.3 m on the ground.
Instead, drawing this road to scale in the style of a divided highway will require assembling it manually from an assortment of black lines and brown infill. Knowing a few things about color priority, we can do it by tracing the two pavement edges and the centerline:
After porting the four lines to OOM:
ckey to join them all into a closed shape.
What if the thing we want to trace is only partially visible? This might happen if a road or trail disappears under tree cover:
801 helpermap part, draw the missing portions with 816.2 Line, site visit needed
CTRL-SHIFT-6) to add notes explaining what you expect to find there
A similar technique can be used to flag other features or locations for a site visit (including points and areas). Aerial imagery will sometimes reveal an object that is difficult to positively identify. Or, maybe you can tell it's a boulder, but need to find it in the field to document its height. Either way, these objects are fun to hunt down, and provide an excuse to test the map-in-progress with a weird sort of orienteering.
If two linear objects are supposed to be connected and at least one of them is dashed—such as 504 Vehicle track, 505 Footpath, and so on—don't let them join at a gap in the dashes (it's ugly and misleading). You can affect the placement of the dashes a couple different ways:
Space-CTRL-Clickan existing vertex to toggle it between a normal vertex (with a blue square) and a dash anchoring point (with a blue diamond)
Some specific cases:
Sometimes you can discern the location of a power line, or the supporting poles, or both from aerial imagery. The pole locations are the most important information. For portions where the poles aren't visible, represent the feature with 816.2 Line, site visit needed until you can capture real-world coordinates for the poles.
If you are lucky enough to have poles visible:
This section reflects an approach we've taken when a power line interacts with certain other features such as roads, paths, traces, and fences. We feel it results in a very clean representation that retains as much useful information as possible. However, it requires that variable symbol 530 Prominent man-made feature—ring be assigned the specific meaning
Utility pole (alternate symbol). The alternate is used in situations where the standard crosspiece ticks would be cluttered or confusing.
When used this way:
Tip: To trim a line that intrudes inside the ring: With the line selected, use the Cut object tool to break the line where it enters and exits the black ring, then
Delete the small segment inside the ring.
Using the techniques we've covered today, you should be equipped—imagery allowing—to map at least some of the following features:
Proceed from larger objects to smaller ones, and get as far as you're able without engaging in undue speculation. You don't necessarily need to absolutely scour every square meter of the available imagery either. That will happen at a later stage anyway!
||2||24%||None vetted, hidden features possible|
||34||22%||None vetted, hidden features possible|
||27||14%||None vetted, hidden features possible|
On Day 5, we'll finally head out the door and start collecting field data. Scheduled to go live on October 11, 2021.
Before heading out the door, charge your phone and configure it for a day of field collection. In the CalTopo phone app:
Folderand name it
000 new. Also create folders for
001 topography pending,
002 earth and rock pending,
003 water pending,
004 vegetation pending,
005 path/built pending,
099 ignore, and
100 processed. Set the visibility for the last two off.
Map Layercombination seems best for your project area
Zoomto your planned parking or access spot
Dragthe marker to the chosen spot, type
Park Here, select the
000 newfolder, and
Save Map, type a suitable name (
San Juan Overlook), and
Tap Save Map
Zoomout until the project area is fully displayed
Tapwhatever map tile or tiles are needed to cover the dotted purple area. Selected tiles are now outlined in yellow.
Max, select whatever layers seem useful, keep an eye on the download size compared to available space, and
Downloaded tiles are cached for up to 30 days. For a long project, you will want to periodically repeat the download.
From OOM, print your map for use in the field (or send a screenshot to your phone).
Appropriate priorities help in two different ways:
There are several different ways to organize priorities.
As pictured, some grid squares, or portions of grid squares, are more important than others. The High Priority areas amount to about 150 acres—concentrate on those, and we're good for our planned events!
Geographic priorities are helpful because they tell us where to focus our efforts. Strategic priorities are just as important because they tell us what to do once we get there.
Our top priority is to map the road, path, and trace network—including parts that are already drawn. Drawn and mapped are two different things! For a linear feature like a road, path, or trace, the difference consists of the Five Effs:
Our second priority is to follow any unexplored edges of the course setting area, possibly discovering and following fences, streams, ridges, or any other evident features that help define and constrain the area.
Our third priority is to correct any contours that fail to adequately represent prominent topographical features such as hills, depressions, spurs, reentrants, plateau edges, or inflection lines. It’s important to correct faulty contours before adding too many other features of lower priority to the same area of the map.
Our fourth priority is to follow any other prominent linear features—fences, power lines, streams, reentrants, spurs, cliffs, gullies, and so on. Many of these will have surfaced as a result of pursuing the first two or three priorities.
Our final priority is penetration: to methodically criss-cross any areas that weren’t already covered by any of our previous forays. The ideal granularity for this task depends on visibility in the area and the nature of the terrain. The goal is to exclude the likelihood that the area could still be concealing unmapped features.
We have a few odds and ends to chase down (or keep an eye on) that don't really fit into any of our other ways of thinking about priorities:
According to our listed priorities, we should start with the path network in high priority zones—the skeleton for what will eventually become a fully-fleshed-out creature.
At this stage, we’re aware of a couple major roads (already drawn), a trail loop somewhere over by the western hill (not drawn), various abandoned road traces (some drawn, some not), and several path-like features that have an uncertain type or location (sketched in red). And we’re very likely to discover additional branches of the network as we go.
It would be smart (see
Footnote) to spend a few minutes planning a route that connects as many high-value targets as possible in whatever time we have available.
Does that sound familiar? That’s pretty much a Score-O—except that we don’t actually know any of the point values in advance. Did we mention that mapping can feel like a weird sort of orienteering?
Footnote:We didn’t actually do the smart thing, but for purposes of this guide, we’re going to pretend that we did.
Physically Follow means that we need to actually walk the line. If the section we’re walking isn’t yet drawn, or is drawn only tentatively, we’ll record a track for it on CalTopo.
Frisk for Further Features means that we’ll remain vigilant for any other mappable features we encounter along the way that aren’t already adequately represented on the map. In CalTopo, we’ll document their presence with point markers.
road trace, etc.)
Account + Map
Tap Record Track
Stay on the path while you’re recording, and conversely, stop recording if you leave the path for some reason.
Tip: GPS tracks can be noisy. Drop an explanatory marker if the path itself has a feature that GPS is unlikely to capture accurately, such as the one pictured.
Marker at GPS
Tap OKand resume walking
In the next few sections, we'll delve deeper into what marker names are all about. Don't worry if these don't quite make sense to you yet!
boulder 1.2/0.7 north side of trail
spot depression, m210 10m to previous boulder
watercourse crossing g60 with bridge
What goes into a marker name? That depends on the nature of the marker. Your preferences may vary, but here are some things to consider:
boulder 1.2/0.7 north side of trail
vehicle track crossing, bearing m300
boulder 1.2/0.7, bearing m120 8m to previous boulder
veg fight northwest corner
watercourse crossing g60 with bridge
For our specific project:
cluster 1.2/0.7 lesser 0.7
scattered boulder field 1.0 southwest corner
Other than that, dimensions are generally optional, though very often helpful, especially if they might later appear on a clue sheet, or if several similar features are near each other that could be differentiated with slightly enlarged or reduced symbols
If you're recording a footpath and encounter another path plus a boulder at the intersection, drop two separate markers:
footpath crossing m150
boulder 1.3/0.9 northwest of crossing
It’s tempting to write all the information on a single marker, but later, when you’re at home processing the data, it’s far too easy to completely miss one of the features.
If you're recording a track for one linear feature and another linear feature runs concurrently with it for a while, you'll need two separate markers, one for the start and one for the end of the concurrence.
start impassable cliff foot south side of road
end imp cliff
If the concurrent object doesn’t originate or terminate on your current track, you’ll likely want to take bearings for the non-concurrent portions of the object.
fence g90 joins north side of trail
fence corner g0 g270 leaves trail
If the overall nature of the current track distinctly changes (enough to warrant a different symbol), drop a marker.
vehicle track becomes trace
erosion gully becomes watercourse
Sometimes we place markers that aren't actually documenting the precise location of a new feature. Maybe we're commenting on or correcting an existing nearby marker, or want to say something we just remembered about a feature a mile away but forgot to write down, or want to mention something we can see but don't have time to get to. In these situations, insert an appropriate keyword in front of the feature name.
sighted large boulder bearing m180 distance 50m
correction boulder here should be large boulder 2.0/1.5
note contours here are wrong
reminder southern fence still needs to be followed
We'll have more to say about this on Day 7.
Once we get home, we port our data to OOM and convert to appropriate symbols. In general, this process is identical to what we've already done on Day 4, except as follows:
000 new folder. To transfer an item,
Edit, change the object's folder using the drop-down, and
Export(file ends up in your default folder)
Bulk Ops), refile the ported objects to the
pendingfolder. Also, turn the visibility for all
pendingfolders off—either that, or change the color of the pending objects to something distinct from those in your
000 newfolder (look under folder
We've covered most of the path network within our high priority areas, so strategic priority one is largely accomplished. Some conclusions we've already reached:
metal object at least 1 m tall, we'll go with
metal utility box at least 0.7 m tall. We've already mapped a fair number of them.
For our second day of collecting field data, we'll explore the perimeter of the course setting area