Another trail map, now with more lines!

Finished Creations
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One of my favorite places to hike is Mount LeConte in the Smokies, and when no better ideas came to us, my wife and I decided to spend our anniversary on another mostly-hiking trip. We’re actually going to stop for a night at the Len Foote Hike Inn in Georgia (a 5-mile hike from the top of Amicalola Falls), then spend a week staying in Gatlinburg and hiking multiple long hikes, and to cap off a perfect plan, we snagged a cancellation spot at LeConte Lodge (the primitive hike-only spot right on top of Mount LeConte).

I’ve apparently made it my tradition to make some sort of… gifts, I guess… to bring up to the Lodge and share with the staff, other guests at our table, and so on. Last November, it was a rather significant amount of fiber-laser-engraved slate (coasters and several 8- and 12-inch square trail maps), but given the short lead time (and perhaps a desire for a bit lighter pack), I figured this trip’s medium would be basswood plywood.

Given the size I was thinking of (12"/300mm squares) I wanted to do something a bit different than just a simple trail map (as nice as those are). My first concept was a cut-and-stack 3D “sculpture” made by laser-cutting elevation contour slices. It could potentially be a two-laser process, cutting the slices on the 100W CO2 gantry laser and then engraving them on the CO2 galvo, even.

I downloaded the 1m-resolution digital elevation data from the USGS via The National Map web site. I could then load all those files into QGIS to combine them into a single elevation layer. I could then use QGIS to extract contours from that layer using various and sundry parameters.

Trying multiple contour spacing options, it was obvious that making a sliced and stacked model wasn’t going to be something I could do easily or quickly, but making a flat engraved trail map with elevation contours seemed feasible and likely to make a nice result. Spacing the contours every 125’ of elevation gave a pleasing distribution, and if I varied the strength of the engraving, I could burn the major contours at 500’ increments with the intermediate ones set such that they fade as the slope goes upward.

I pulled the trails from OpenStreetMap data, which I downloaded and then culled to the required segments in QGIS. I also included Newfound Gap Road, as it ties together two trailheads (and has a loop and a little Godzilla hiking the Appalachian Trail). I then exported each set of contours, the trails, and the road as separate SVGs. I loaded those into Inkscape in order to use the Hershey Text plugin to make the trail labels. (The map title is just the National Park Typeface as a standard font.)

Finally, I loaded the very large SVG from Inkscape into LightBurn, which handled the rather excessive path data with aplomb. (LightBurn actually handled it much more responsively than Inkscape.) I set four progressively faster speeds for the four sets of contour lines, plus additional settings for the road, trails, and labels, all at 100% of my CO2 galvo’s 30W:

  • Contour 000: 375mm/s
  • Contour 125: 750mm/s
  • Contour 250: 1500mm/s
  • Contour 375: 2000mm/s
  • Trails and Title: 100mm/s
  • Road: 200mm/s
  • Labels: 200mm/s with two passes

I was happy enough with the results I got using a 400mm f-theta lens on my upgraded CO2 galvo (20mm galvo head and 6x beam expander, IIRC, up from the 10mm/3x combo it was originally). I could do a full 12"/300mm engrave in 2:26 for the side with labels and 1:49 for the plain contours-and-trails side.

Trail map with contours
Trail map with contours1920×980 713 KB

I ended up making five with 1/8" basswood plywood and a pair with 1/4" basswood plywood. (I also prototyped on 1/16" basswood plywood, but it wasn’t much cheaper at all than 1/8", and it was very floppy.) Of course, 12"/300mm squares a bit large for a general hiker to pack in their bag, so I figured I should make some 150mm/6" ones, too. For that, I just cut a few 1/8" pieces into four 150mm squares each (with 5mm rounded corners, since that’s so easy to do in LightBurn). I cut the squares on the 100W CO2 gantry laser while I was engraving on the CO2 galvo, so that was nice. (The engraving took the CO2 galvo about 80 seconds for the labeled fronts and just under a minute for the plain backs, using a 210mm f-theta lens for higher detail.)

The collection
The collection1920×1501 901 KB

It was fun to play around again with USGS and OpenStreetMap data in QGIS, and I rather like the results. (I intentionally didn’t clip out contours behind the text for this set, but if you wanted a gift-shop-style extra legible version, that would probably be a thing to do.) Anyway, it was a fun project, and one of these days when MillMage supports carving relief from heightmap data, I’ll have to try it out for another run of to-scale terrain relief models (and if I can eventually use my CNC router’s diode laser to engrave the trails right onto the surface without my old hacks, I’d be in maker heaven, hehe).

Anyway, I’d better get packing. I think the laundry just finished. :sweat_smile:

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Looks great… Can you be a bit more specific on how you create the original artwork?

I live in the middle of Arizona and tried your links, but seem to be missing a lot of the trails and roadways.

I’m also not clear how you made them into a single layer using QGIS…?

Thanks.

:grinning_cat:

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Can I be more specific? Oh, I can certainly be more specific. :rofl:

Since it’ll likely help me, too, in the future when I’m trying to remember how I did things, I suppose I’ll just type up some possibly excessive notes on how I did much of it. This is obviously not intended to be comprehensive, as working with GIS can obviously be quite extensive. This might be enough to get started well enough to begin understanding some of the way you can do things in QGIS, at least.

To get the trails and roads, I used one of the OpenStreetMap “processed data providers”, specifically, download.geofabrik.de. For data just for Arizona, I would go to the homepage, then…

  1. Click on “North America” under “Sub Region”
  2. Click on “United States of America” under “Sub Regions”
  3. Click on “Arizona” under “Sub Regions”
  4. Click on the “experimental arizona-latest-free-gpkg.zip” link to download the data. (I like the GeoPackage format best from their options when I’m going to be using it in QGIS.)

To use the data in QGIS:

  1. “Layer” menu
  2. “Add Layer”
  3. “Add Vector Layer…”
  4. Select your file (Source Type: File, Source Vector Dataset(s): browse to the file)
  5. Click “Add”
  6. Choose which layers you’d like to add:
    • gis_osm_roads_free (LineString) has roads and trails
    • gis_osm_waterways_free (LineString) has rivers and streams and such
    • …and so on. Go wild. You can always remove layers later.
  7. Click “Add Layers”

Procuring elevation data from The National Map:

  1. Go to TNM Download.
  2. Pan and zoom the map to your area of interest.
  3. Under “Data”, check “Elevation Products (3D Elevation Program Products and Services)” to expand that option.
  4. Make your Subcategory selections:
    • Click the “Show” link under a given category to see if there’s coverage of your desired area in that resolution.
    • 1 arc-second is approximately 30m/100’ and has nearly universal coverage
    • 1/3 arc-second is approximately 10m/33’ and generally has great coverage
    • 1/9 arc-second is approximately 1m/3’ and often has sparse coverage
    • 1-meter is great if you want maximum detail, and it seems to have better coverage than 1/9 arc-second
  5. For DEM products, “File Formats” is pretty much going to be GeoTIFF.
  6. Click the blue “Search Products” button near the top of the panel.
  7. The “Products” tab will now list all the files matching your selection.
    • There can sometimes be a significant number of files, each with an arbitrary amount of heightmap data.
    • You can download individual files via each entry’s “Download Link (TIF)”
    • You can click the cart icon for each and add them to your cart (enabling batch downloads)
  8. If you used the cart, click to the “Cart” tab where you have more convenient download links and the ability to grab a text file or CSV for batch downloading (see “uGet Instructions” by the TXT/CSV file icons at the top for batch downloading instructions).

Loading and merging your downloaded DEM GeoTIFFs in QGIS:

  1. “Layer” menu
  2. “Add Layer”
  3. “Add Raster Layer…”
  4. Select all your GeoTIFF files (Source Type: File, Source Vector Dataset(s): browse to the folder and multi-select)
  5. Click “Add”
  6. You may be asked to convert Coordinate Reference Systems. (USGS DEM data is NAD83, and my projects and OpenStreetMap data are generally WGS 84, so QGIS needs to do the coordinate transformation for every file.)
  7. Click through to finish loading the GeoTIFFs.
  8. “Raster” menu
  9. “Miscellaneous”
  10. “Merge…”
  11. Click the “…” button for “Input layers” to select your raster layers to merge.
  12. Select all the relevant raster layers.
  13. Click the triangle back button left of “Input Layers” above the layer list to go back to the Parameters page.
  14. Scroll down to the box labeled “Merged” that says “[Save to temporary file]”
  15. Click the “…” button to the right of that input line and choose “Save to File…”
  16. Choose where to save the file and what to name it. (GeoPackage is the default type, and it is what I would recommend.)
  17. Now click “Run”
  18. Wait for the merge to complete. (GDAL output will show in the dialog’s log tab.)
  19. You should end up with a new layer in the layer list with your merged data.
  20. Close the Merge dialog and uncheck or remove your source layers in the layer list.

Clipping some data in QGIS:

  1. “Layer”
  2. “Create Layer”
  3. “New GeoPackage Layer”
  4. Choose a name a folder to save the new layer
  5. Set “Geometry type” to “Polygon”
  6. Leaving the Coordinate Reference System as WGS 84 is fine
  7. Click “OK” to create the new layer and add it to the layer list
  8. Click the single pencil icon to “Toggle Editing” on the new layer
  9. Click the blobby icon to “Add Polygon Feature”
  10. Click points to make a shape that contains your desired area, right-clicking to finish.
  11. A “Feature Attributes” box will pop up asking for a “fid”. Leave it on “Autogenerate” and just click “OK”.
  12. Click the single pencil “Toggle Editing” icon to finish editing
  13. Obviously, save the changes
  14. If you want a rectangle (in coordinate space):
    1. “Vector” menu
    2. “Research Tools”
    3. “Extract Layer Extent…”
    4. Choose your layer (with your just-drawn shape)
    5. Optionally, click the “…” button by the “[Create temporary layer]” box so you have the new extant layer to keep.
    6. Click “Run”
    7. A new vector layer with one shape, a rectangle aligned to coordinate space, will be created.
  15. Clipping a vector layer (i.e. your roads and trails):
    1. “Vector” menu
    2. “Geoprocessing Tools”
    3. “Clip…”
    4. Input layer: select your source vector layer.
    5. Overlay layer: select your layer with the drawn shape or extracted extant.
    6. Optionally, click the “…” button by the “[Create temporary layer]” box so you have the new clipped layer to keep.
    7. Click “Run”
    8. Click “Close” when done. The new clipped layer is in the layers list.
  16. Clipping a raster layer (i.e. your DEM data):
    1. “Raster” menu
    2. “Extraction”
    3. “Clip Raster by Mask Layer…”
    4. Input layer: select your source raster layer.
    5. Mask layer: select your layer with the drawn shape or extracted extant.
    6. Optionally, click the “…” button by the “[Save to temporary file]” box (way down the scroll) so you have the new clipped layer to keep.
    7. Click “Run”
    8. Click “Close” when done. The new clipped layer is in the layers list.

Now, as for making contour lines from the raster data:

  1. “Raster” menu
  2. “Extraction”
  3. “Contour…”
  4. Choose your parameters and run. (This is left as an exercise for the reader, who has definitely got this part down by now.)
  5. If you’re going to export the contour lines (or any vector layer), when you right-click the layer and choose “Export”, “Save Features As…”, you’ll probably want to export as “AutoCAD DXF”.

Anyway… That should be enough to at least play around a bit. Anyone can feel free to ask questions or whatever, but I am, of course, going to be out of reach for just a bit.

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Thanks so much for the detail… Getting around USA gov sites are usually a headache anyway.

I doubt I’ve have ended up with this procedure, so thanks…

Will give it a shot when I get out of bed… :face_with_spiral_eyes:

:grinning_cat:

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