In yesterday’s post about Get-A-Route, a site that lets you create GPX routes, or convert Google Maps routes and driving directions into GPX route files, my biggest complaint was that you couldn’t move or delete placemarks on a route you created yourself, as you could with Marengo. Sergey writes to say he’s already fixed that; you can now drag and drop placemarks, and delete them with a right-click. This works only in Step-By-Step mode; in Automatic Route mode, the placemarks in the GPX route file are fixed automatically by the driving directions. But you probably wouldn’t want to change those in any case …
Archive for September, 2007
The OpenStreetMap project is “a free editable map of the whole world”, created by users with GPS data or by tracing over Yahoo Maps images (allowed by Yahoo) or public domain Landsat data. Data is viewable by anyone; registration assigns you a username and password that lets you contribute your own data to the project, using a multi-platform map editor like JOSM or Meerkartor. JOSM also lets you save downloaded data from OpenStreetMap, and this data can be converted to the .img format used by Garmin mapping GPS units, or converted to a GPX file for general import into GPS units.
The current OSM data in Garmin .img format is available for the UK, South Africa, and Africa at the Mkgmap wiki site, and for Germany/Netherlands and the entire world at this site. But if you want the most recent data, data subsets for different areas, or don’t want the entire dataset for the world, you can download data for a specific area from OpenStreetMap and convert it yourself to a Garmin .img file. Data coverage is still spotty, so you should check the OpenStreetMap site to see whether the area you’re interested in has data. If yes:
1. Click the “Download some data from the OSM server” link in JOSM, and specify the latitude/longitude bounds of the area you’re interested in (no more than 0.25 degrees square) (note: you’ll need to have entered your OSM username and password in the preferences section).
2. Save the downloaded data as an *.osm file if you want to convert it to Garmin format, else save it as a GPX file.
3. Use the command line Java program Mkgmap to convert the *.osm file to a Garmin img map file (always the same output filename, “63240001.img”, but you can rename it to a different 8-digit number after creation) . If your osm file is called test.osm and is in the same directory as mkgmap.jar, the command syntax is “java -jar mkgmap.jar test.osm”. Enter the appropriate data path if it’s located in a different directory, but the 63240001.img file will always be created in the directory where mkgmap.jar is located. If you’d prefer a GUI, I’ve created a simple one for Windows that you can download here; unzip it to the same directory as mkgmap.jar and run it. The *.osm file will have to be in the same directory as mkgmap.jar for this GUI to work; sorry about that.
4. Upload the .img file to your Garmin GPS using a program like sendMap, or MapUpload if you have a compatible Garmin unit. For GPX files, use the upload program of your choice (e.g. GPS TrackMaker or EasyGPS).
Thanks to David from the UK for the tip.
I posted before about Marengo, a free site that lets you create routes waypoint by waypoint in a Google Maps interface, and then convert them to a GPX route for upload to a GPS unit (a new paid version, 5 pounds a year, lets you save routes for future access). There’s a brand new site called Get-A-Route that lets you do the same thing point-by-point, but it’s not as easy to use in that mode as Marengo. In Get-A-Route, you can set the start and and end destinations as points in “Step-By-Step Route” mode, and then manually select additional points for the route. Unlike Marengo, you can’t move or delete waypoints after you create them; if you mess up, you have to start again with the two endpoints. And placing waypoints exactly where you want them can be a pain. (9/27/07: Fixed just one day later; see this post for more info).
But Get-A-Route has a nifty feature that Marengo lacks. In “Automatic Route” mode, enter your “From” and “To” addresses, and click on “Get A Route”. You’ll get the standard list of Google driving directions, and the route drawn on a Google Maps interface. But you’ll also have the option to download a GPX route file (or OziExplorer Waypoint or Route file) that contains waypoint markers for every critical direction point in the Google Maps driving directions. Then use a program like EasyGPS or GPS TrackMaker to upload the route to your GPS receiver. It’s a way to get direction routing on a GPS that doesn’t support it, especially if you print out the Google Maps driving directions as well.
Thanks to Sergey for the tip.
The state of Utah’s Automated Geographic Reference Center (AGRC) has spectacular high-resolution color aerial photography and digital elevation model (DEM) data available for the entire state, with limited areas having even higher spatial resolution.
- 5-meter DEM data derived from aerial orthophotos is available for the entire state in ASCII ArcGrid (*.asc) format. You can use the FTP site along with statewide index shapefile to determine which files to download, or use the Interactive Map site. You may have to right-click on the file and choose “Save Link (Target) As”, otherwise the ASCII Grid files may open up as text in your browser. MicroDEM can open ASCII ArcGrid files directly (if you get an error message, zip the DEM file, then open the zipped file). Here’s a reflectance image of a 5-meter DEM of the Zion National Park area:
Continue reading ‘High-Resolution Aerial Photography And DEM Data For Utah’
The TatukGIS Viewer and MicroDEM are handy all-purpose utilities to use for embedding and extracting worldfile data from a variety of image formats. But if you’re only working with TIFF image files and their worldfiles (*.tfw, *.tifw), GeoTiffExaminer may be a better choice:
- Small program (less than 500K installed)
- Modifies only the header, and doesn’t touch the image data. Both TatukGIS Viewer and MicroDEM rewrite the images when they save them, and sometimes you can get minor shifts in the color palettes that way
- Supports indexed color (the standard format for USGS DRG topo maps); MicroDEM doesn’t, and TatukGIS Viewer doesn’t always save the color palette on indexed colors correctly.
- Simple interface
There are two modes of operation: opening a GeoTiff, extracting the geodata and using it to create a worldfile; and opening a plain TIF file with a worldfile, and embedding the geodata from the worldfile in the TIF to create a GeoTiff.
Continue reading ‘Handling TIFF WorldFiles With GeoTiffExaminer’
Intel has released “Mash Maker“, another mashup maker to join those from Google, Yahoo and Microsoft. This one’s a bit different, though:
- It’s not a stand-alone web app, but installs as a toolbar on your browser
- As you visit sites that lend themselves to mashups, Mash Maker will suggest possible mashups to you based on the site content and structure
- You can add data from one website to that from another website with a simple copy-and-paste function, mashing up data from both sites simultaneously
- The interface is simple and easy to use, albeit not with the same flexibility and power as the other mashup makers
- Mash Maker extracts data and determines possible mashups using a structure/semantic model for specific websites generated by users and stored on their server. If you find a website for which no structure/semantic model has been created, you can create a new one that will let others create mashups with that site. You can also modify a current model to add new capabilities.
- Google Maps mashups, of course, but also ones that let you create tables, annotate items, and join data from one website with that of another.
Visit the Mash Maker page to sign up and for more info; you can view examples of its use on the Video page.
Orbiting satellites often have two types of digital imaging sensors:
- Multispectral, i.e. different sensors for different colors (including IR), or different filters in front of the same sensor. Each individual band can be shown as a black-and-white image; multiple bands can each be assigned a color, and combined to form an RGB color image.
- Panchromatic, “meaning all the colors”, a single broad-spectrum sensor. This are usually displayed as a monochromatic image (i.e. black-and-white).
The panchromatic sensors usually have a higher spatial resolution than the multispectral. For example, on the Landsat 7 spacecraft, the 6 multispectral bands have a spatial resolution of roughly 30 meters (a seventh has 60 meters), while the panchromatic sensor has a resolution of about 15 meters. Here’s an example of an image created from three of the Landsat multispectral bands (data from the Global Land Cover Facility):
In a previous post on large-format downloadable historical maps, I noted that the Perry-Castaneda Map Library has an interesting digital collection of Army Map Service topographic maps dating from the 1940s and 1950s, covering large areas of Asia and Africa, along with city maps for Japan, China, Korea and Taiwan (Formosa). Over on the Google Earth Community, “PriceCollins” has been creating a KMZ index file for these maps. So far, he has indexed all 435 city maps:
And 413 1:250K maps covering most of India, Pakistan and Southeast Asia:
Each city and rectangle placemark contains a direct download link to the map image at the Perry-Castaneda Library. From the post, it sounds like eventually all the maps will be indexed in this fashion, so it’s worth bookmarking the site and checking it regularly for updates.
