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Archive for the 'topographic maps' Category

Where’s The Path – UK OS Mapping Viewer And Tool

Where’s The Path lets you display UK Ordnance Survey 1:50K topographic maps side by side with other kinds of maps, including:

  • Google roads/satellite/terrain/hybrid
  • OpenStreetMap
  • 1930s and 1940s OS maps

Cursor movement on one map is mirrored in another; you can import  GPX/KML files, and also draw features on the map and export them to in GPX/KML format. Overlay multiple types of grids (lat/long and UKOS); toggle a Panoramio layer to see photos taken at locations within the map view:


Most annoying aspect is that it’s only for the UK; wish someone could put something similar together for the US.

HT to Trev Broomfield.

TopOSM – An Open Street Map Based Topographic Map

I’ve been checking in on Lars Ahlzen’s TopOSM site occasionally for a while now; he’s had a web-based map server with really nice Open-Street-Map-based topographic maps for Massachusetts and Colorado for a while now, but there hadn’t been any new additions for a while. Via the Mapperz blog, I see that there’s been a major addition in the past few months, with data added for the Western US (California, Nevada, Oregon and Washington). These are really nice-looking maps, with relief-shaded terrain, contour lines and road/trail data from the OSM project; starting view is centered around San Francisco:

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Topographic Maps For The US And Canada In A Google Maps Interface

Joseph Elfelt writes to announce his Gmap4 website, which displays the MyTopo version of USGS topographic maps (down to 1:24K scale) and Canadian topo maps (to 1:50K) in a Google Maps interface; standard Google Maps layers are available as well. The initial map window view is pretty small; for a better view, select “Full Screen” from the action menu.  The US topo maps are very high-quality terrain shaded maps, better than Terraserver, and substitute the updated US Forest Service topos where available:


The Canadian maps generally look good as well, though they sometimes have issues with border mismatch between tiles, and differences in map lightness:


You can also display GPX and KML files on top of the topo maps, like this KML file:


The help file, available as a PDF from the “Action” drop-down menu in the upper-right corner, explains how to do this three ways:

The site is non-commercial and ad-free, to conform to the licensing limitations of the MyTopo API.

Map Folding

If you still do old-school navigation with map and compass, the US Army’s Field Manual on Map Reading And Navigation is an excellent resource. You can buy a copy if you like, but there’s an HTML version here, Google Books has it available in poor quality scanned form here, and you can view/download a PDF copy from Scribd here (book is in the public domain).  In one of the appendices, it has diagrams showing three different ways to fold a map so that you can view parts of it without completely unfolding it. The first two are self-explanatory:


The third one, the “Protection Method”, is a nifty way to fold a map so that it takes up 1/4 of its original size so that you can paste it into a notebook, but still have all sections of it accessible for viewing:


Had to try it out to figure out what was going on. After you’ve completed the full set of folds, adhere the undersides of sections A, F, L and Q to your notebook page. You can then view the various quadrants (A-D, E-H, J-M and N-Q) by flipping the sheets over the horizontal and vertical folds that cross the quadrants. Try it with a scrap piece of paper first :).

If you have a square map and want to try something different, you might try the Turkish Map Fold; I couldn’t quite figure it out myself.

A Look At The New USGS Quad Format

Via the All Directions Blog comes word that the first “beta” versions of the new digital USGS 7.5-minute quad maps are now available at the USGS Map Store; click on the yellow button that says “Show DigMaps-Beta” to display their positions in the Google Maps interface. Before you get too excited, you should note:

  • Only maps from Arizona are currently available, and even then not the whole state (there’s a big hole around where I live)Coverage is currently limited, but more states are being added all the time:


(The coordinate indicator down at the lower right is new, and a nice touch – lat/long and USNG coordinates that reflect the current cursor position)

  • These are quads, but they’re not topo quads yet – contour lines are missing, as is all hydrographic data.
  • Worst of all, they’re in GeoPDF format only. Windows users will need the free GeoPDF plugin to take advantage of features like live coordinate readout, measurements, alternate coordinates, grids, etc.; there’s no plug-in yet for Mac and Linux users, though they can still view the files in Acrobat Reader with layers.
  • They’re not available in standard graphic formats like TIFF or GIF, but there’s a way around that – more on that later.

Open up one of these new quad PDF files, and you’ll see a layers panel at the left:


Clicking the “eye” will turn a layer on and off; presumably, when contour lines are added, these can be turned on and off as well. Most of these layers are vector in nature, with one big exception, the “Orthoimage” layer; this is a full-color aerial photograph that can be placed on the map as a background:


This is both great, and a pain to use. Great because aerial photos on USGS maps rock; a pain because it slows things down and lot.  Every time you pan the map, the orthoimage needs to get redrawn completely; same thing every time you turn a vector layer on and off. It’s slow even on my quad-core desktop; on my netbook, it’s unusable. You’ll probably find yourself turning this layer off unless it’s absolutely necessary. Supposedly, later versions of these maps will have the old-style raster topo maps available as a layer, and I’m guessing they’ll be slow, too. Orthoimage resolution appears to be about 1-meter; in the picture below, the smallest square is about 1 meter by 1 meter, and the next square grouping is 8 meters by 8 meters:


All of the vector layers, including labels, roads, and grids, blow up very nicely when you zoom in – no more aliasing effects as with the old raster maps:


And the roads line up perfectly with the underlying imagery, which definitely wasn’t always true with the old USGS topo maps, either:


In appearance and utility, these maps looks like a big step ahead, and I look forward to seeing them with contour lines on top. But the format is a big problem – AFAIK, only Acrobat Reader with the GeoPDF plugin lets you look at these maps with georeferenced coordinate data. GeoPDF is being promoted as an open standard, and eventually more GIS programs will be able to handle these maps directly, but right now most (all?) don’t, and I doubt most graphic editors will be able to open and edit GeoPDFs anytime soon.

I’ve covered a way around this problem before. The free utility PDFCreator lets you “print” a file to a number of graphic formats like JPG, TIF, GIF, PNG, etc.; see this post for more details. So from Acrobat Reader, you could “print” the map into a TIF file. Depending on the output resolution you select, you’re likely to get some raster aliasing effects in the final map, but it still looks better than the old format USGS maps. The example below was “printed” at a 300 dpi resolution:


The image won’t be georeferenced, but since the map is in the UTM NAD83 projection, georeferencing can be done easily and accurately using any number of free programs (which I’ll get around to covering sometime soon). Just convert the lat/long of the quad corners to UTM coordinates, and then use these corners as the reference points for registration:


The very outside tip of the corner corresponds to 36N, 112W; convert that to UTM (409871E, 3984411N), and you can then use that corner for registration. Repeat as needed for the other corners.

Solid 3D Landscape Models From LandPrint

A bit of a departure from the usual posts, since this service is definitely not free. I just purchased a solid 3D landscape model from and thought I’d review the creation process and the results, offer my opinion, and give some tips for getting the best results if you order your own.

LandPrint lets you select a square/rectangular section of the Earth’s terrain, and creates a small 3D model of that terrain along with your choice of overlays:

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USGS Topographic Map Overlays For Google Earth

Over at the Google Earth Library site, Matt has started a project to convert USGS topographic maps (1:250K, 1:100K and 1:24K scales) into Google Earth overlays.. These are “super” overlays, where views from higher elevations are at lower resolutions, while closer views load in high-resolution imagery; this speeds up display times significantly. Arizona and Nevada are available now, with Colorado and California coming soon.

The network link to access the overlays online is at the bottom of the web page; click on the “G-Earth” graphic. Once loaded in Google Earth, activate it, then expand it to select the state and map type you want, 1:24K maps for Arizona here:

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Garmin Topo Maps For Afghanistan, Baghdad

Just noticed on the GPSFileDepot site that they’ve started posting 20-ft.-contour topographic maps for Afghanistan for Garmin GPS units, created by Steakhouse Studio. Here’s a MapSource screenshot of the Kandahar area:

Garmin topo map of Afghanistan

Twenty-five topo maps are currently available, covering one-by-one or one-by-two degree quadrangles; by my best estimate, this covers roughly a half of Aghanistan’s territory, but it looks like new maps are being added on a regular basis. The link page also include road maps for Afghanistan as a whole, and for metro Kabul.

Also at GPSFileDepot is a Garmin topo map for the Baghdad, Iraq area, with 20-ft. countours, roads and points of interest. Plus, there’s a permanent download page for the routable Garmin map of Baghdad mentioned in an earlier post.

Windows and Mac installers available for all these mapsets.

Addendum (5/22/2009): An upgraded set of these maps is available for US Government use only; contact the author for info.