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Archive for the 'KML' Category

Geodetic Tools For Google Earth

Two weeks ago, I posted about a web app from Metzger and Willard that offers useful info like PLSS data and a topo quad index in a Google Earth plugin interface. Poking around their site further, turns out they have a page called Earth Survey, a set of KML network links that installs those features into the stand-alone version of Google Earth, plus additional links that offer data not found in that web app. KML network links include:

QUADS – Displays an index for USGS quad maps, and also the maps themselves as an overlay. Also has overlays for aerial digital orthoquads (color and B&W), and shaded relief maps (color and B&W). The color relief is pretty low-res, though, and the B&W relief appears to be based on unpatched SRTM data, as it has a fair number of holes:

relief

 

MagDec– Magnetic declination for any point in the world:

magdec

PLSGE- Township/range/section/quadrant/subquadrant, meridian and special survey overlays:

2011-07-05_143305

RINGS – Easy range ring generator for Google Earth:

ringssetup

ringsdrawn

Rings show up in a separate folder called “Saved Places”; right-click on that folder and choose “Save As”, and you can save the rings as a static KML file for future use.

NGSCS – National Geodetic Survey Control Stations. Note that you have to click on Query Setup to specify search conditions, and then check the Search Results box in the Place pane to view them. Unlike the web app, there doesn’t appear to be a way to save a static KML file for a control station, though you can save the network link for that search result.

control

Other available links include a NAD27 to NAD83 shift calculator, a State Plane Coordinate System (SPCS) converter,  and front-ends for the NGS online tools DEFLEC09 (“represents the deflections of the vertical at the surface of the Earth.”),  GEOID09 (“refined hybrid model of the geoid in the United States and other territories”), VERTCON (“NGVD29-to-NAVD88 and NAVD88-to-NGVD29 orthoheight conversions”), and XYZ (“converting between Geodetic Latitude-Longitude-Ellipsoid_ht and XYZ on the GRS80 Ellipsoid”).




Earth Survey Plugin: NGS Benchmarks, PLSS Data, USGS Quad Data And More

A while back, I posted about a free web app from Metzger and Willard that shows National Geodetic Survey control points (benchmarks) near a specific area, and lets you view data for those landmarks. I’ve just noticed that they’ve created a newer web app called the Earth Survey Plugin, running in a Google Earth browser plugin that not only has the same capability, but also adds a bunch of additional features:

  • An NGS Survey Marker capability that works very similarly to the previous app, but now offers the ability to export the data into a static KML file
  • A PLSS point geocoder function that either gives you the section data for the point in the middle of the display:

plsspoint

… or lets you enter the PLSS parameters, and find the center point associate with them:

plsslookup

These can also be saved as a KML file.

  • A click-to-geocode function:

geocoder

Plus, a set of overlays:

  • PLSS sections, including quadrants and subquadrants:

plssquads

  • Principal meridians:

meridians

  • USGS topo quad index; orange dots for 1:24K, purple for 1:100K, cyan for 1:250K. Clicking on a dot brings up a pop-up balloon with the name of a quad, and a direct link to the GeoPDF for that quad at the USGS store. Note that GeoPDF quads are not currently available for quads in US National Forests, and that at this time, some states (e.g. AZ, CA) don’t have full topographic information on their GeoPDF quads.

usgsindex

  • Actual USGS topo map views, with the scale depending on your zoom level.



Hey, ArcGIS Explorer Desktop Has Turned Out Pretty Good!

Yeah, that’s not news to a lot of you, but it is to me. My last significant exposure to ESRI’s ArcGIS Explorer digital globe software (Windows only) was back when it came out, quite a few years ago. I tried it, and found it inferior to Google Earth in performance in 3D, and too complicated to bother learning it; since then, I’ve stuck strictly with Google Earth. A recent post on the free Garmin Tool application, which creates Garmin Custom Map overlays using ArcGIS Explorer, forced me to look at it again, and I was surprised to discover that it’s turned into a pretty cool, and pretty useful tool. Not perfect – the 3D performance is still pretty weak compared to Google Earth, and the out-of-the-box configuration isn’t as strong. But it has it’s own very strong set of features, and when used in 2D mode, is a good addition to any geography toolbox. Nice re-organization of tools/features in a MS-Word-like ribbon format, much better than the original interface.

  • A good selection of basemap imagery sets, including Bing Maps (aerial/road/hybrid), general world imagery/topographic/road maps, OSM, general terrain shading and National Geographic shaded topo maps:

natgeo

No vector basemap data, like the roads you’ll find in Google Earth.

  • Add raster/vector data from multiple data sources and types: ArcGIS Online, GIS web services (ArcGIS servers, GeoRSS, WMS), ArcGIS lyr files, shapefiles, KML, GeoDatabases, text files, georeferenced raster imagery (e.g. GeoTiffs), and GPS data files (GPX).
  • Vector editing tools: Point, Line Area, Circle, Rectangle.
  • Export data in KML format (for user-created vector data), nmc map content packages for other ArcGIS Explorer users, or lpk layer files for ArcGIS.
  • Driving directions/routing
  • Add links to non-geographic data (documents, images)
  • Measurement tools for distance/area
  • Create a slide presentation by saving a series of map views
  • Time/flight animations

Oh the “needs work” side:

  • In the default install, I can’t find a way to set shapefile colors/sizes/symbols to depend on attribute values. For example, if you have an area shapefile with multiple subareas, each depicting an area with a separate property, they’re all displayed with the same color. For a GIS data viewer, this is a major missing feature. No selection/filtering by attribute either. The only way to view attribute data is through an on-screen pop-up; no tabular views of the DBF data.
  • I initially thought there was no adjustable transparency for raster/vector layers, but it’s under the Appearance ribbon tab, instead of in the Properties window for each layer, which is where you’d normally expect to find it.
  • Zoom and tilt controls are the opposite of every other digital globe I’ve used; scroll the mouse wheel away from you to zoom in, click the center button and move the mouse away from you to tilt the view to an oblique angle. And boy, can it be unresponsive sometimes in 3D mode! I usually only use the program in 2D mode only, so as not to have to deal with those issues.
  • There’s a nice interface for querying/previewing datasets available in ArcGIS Online, but there’s no comparable gallery of pre-packaged content files (NMC/NMF files) anywhere on the ArcGIS website, at least that I could find.
  • The app comes with the ability to add GIS-like analysis tools, as well as utilities like the Garmin Tool mentioned above (created with .Net and a free SDK kit from ESRI). By default, it comes with a buffer tool only; the process for adding additional tools isn’t explained very clearly in the help file. And while there’s a fair number of tools available, they’re hard to find; there doesn’t seem to be any systematic directory or catalog of them on the ArcGIS site. With some work, I tracked down some of them, and will post on them tomorrow.



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:

wheresthepath

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.




Displaying GPS Data On A Website

Got an email a few weeks ago from someone who wanted to post data taken with a GPS, in GPX file format, and display it as an embeddable map on his blog; he couldn’t find anything on that on the web. I offered one possibility, and he in turn suggested that I might put up a brief post on the topic. Here’s a few ways to do it, off the top of my head.

Some of these will require you to convert your GPX data into an alternate format, like KML or shapefile. A search of this website will bring up lots of programs that can do these conversions, but probably the simplest way is to load your GPX file into Google Earth, then export the data in KML or KMZ format. Note: All of these sites require you to create a free account.

Google Maps My Maps – The alternative I suggested; not a lot of features, but very easy to use. Import KML/KMZ files from your computer or a web link, use the built-in editor to add additional features. You can then display the map on your website using a widget.

Google Docs Spreadsheet – If you convert your GPX files to CSV files using a program like DNRGarmin or GPXToPOI, you can import the data into a Google Docs spreadsheet; Google offers a tutorial on converting that data into a KML network link for display in Google Maps or the Google Earth plugin.

GeoCommons – Just posted about this yesterday; upload your data and display it in widget format. All data you upload will be available for anyone to use or download.

MapChannels – Lots of map creation features, and embeddable maps.

ScribbleMaps Pro – Similar to Google Maps My Maps, but offers lots more import options and drawing tools. Highly recommended.

Feel free to add your own recommendations in the comments section.




Near-Real-Time US Airline Flight Visualization In Google Earth

New from Google, a Google Earth network link that shows near-real-time US flight positions, full 3D position:

3datlanta

Mouse-over a plane, and see the route it’s taken up to that point in blue:

route

Click on a plane, and get a pop-up with flight info, on-time status:

bubble

Click on “Download flight path”, and download a KML time animation of the plane’s flight to that point; click on the play button at upper right to start the animation.

Flight info is delayed roughly 15 minutes.

Via Google LatLong Blog.




Crowdsourcing And Coordinating Data Collection With Handheld GPS Units

Got an email today from someone with a data collection/coordination/assembly problem. They have multiple people out in the field with Garmin GPS units recording data, and bringing it back to a central location for collation/combination when they’re done. Since Garmin GPS units have limited capabilities for data storage – coordinates, name, comment, date and time, elevation, and that’s pretty much it – additional data associated with a point has to be recorded by hand. Once back from the field, data has to be downloaded from individual units, associated with the additional attribute data from forms, all the data combined together into a single dataset, then converted into GIS-friendly format. And the process they had come up with wasn’t really working well for them.

I think this highlights some of the major limitations of classic stand-alone handheld GPS units. They’re really designed for us in personal data collection, not combined data collection; assembling data from multiple units can take a lot of work. Plus, their limited data collection capabilities require offloading data attribute acquisition to other formats (e.g. pencil and paper), adding the addition problem of associating that data with coordinates later on. There are lots of professional solutions for these problems, like Trimble or MobileMapper GPS units, Terrasync and ArcPad software, but these can be complicated and expensive. I challenge you to find anyone with enough patience to use Terrasync for a single day without swearing at least once; I know I can’t  ;-).

For a few years, I’ve had CyberTracker on my list of potential topics to post on. CyberTracker is a terrific data acquisition and collation tool for field data with tons of great features, like custom data acquisition form design for easy data entry, moving maps, easy data collation and conversion to GIS-friendly format. Plus, the software is free, and the hardware is (relatively) affordable. But unfortunately, I think time and technology are passing Cybertracker by:

  • While the central data software runs on Windows, the field data collection software runs on old-school Palm OS and Windows Mobile. Palm OS is dead; Windows Mobile development has stopped with version 6.5, and only maintenance updates are scheduled. So the useful lifetime of any data collection system built around CyberTracker is limited. If you need a fast/cheap/short-term solution, CyberTracker is free for non-profit use, and you could probably pick up the hardware very cheaply on eBay. Long-term, I don’t see it having much of a future in its current form.
  • The data collation model is also becoming obsolete. With CyberTracker, you have to bring all the data units to a single data download/collation computer. While there are still places in the world where this might make sense, an increasingly-connected world means that data download/collation to the cloud instead of an individual computer makes more sense.

I’m really excited about the possibilities for crowdsourced geographic data collection and collation using portable devices running Android OS (yeah, iOS too). There are already several interesting apps for doing this, and I hope to cover some of those soon on my AndroGeoid website. And I suspect that the small number of apps that can currently do this will be quickly joined by far more apps, and far more capable apps, in the very near future. But that doesn’t help with my emailer’s current problem. I suspect there are many different ways you could do this, but here’s the first approach that came to me using all-free software and services.

1. Make sure that everyone on the project has a Google account (i.e. Gmail); completely free.

2. Have the project leader created a single main data spreadsheet on Google Docs, with all the desired data attributes (e.g. point name, coordinates, comments, additional data fields from the paper forms, etc.) and share a link to that spreadsheet with other project members so that they can edit it as well.

3. Project members can download data from their Garmin units using DNRGarmin, and then export the data from DNRGarmin in CSV format.

4. Load the data into the spreadsheet program of your choice, and add/edit data from data forms to make it conform to the data structure of the main Google Docs spreadsheet.

5. Copy the data cells in the spreadsheet program, and paste them into the main Google Docs spreadsheet. Note: Use Ctrl-C and Ctrl-V to copy and paste cells into Google Docs instead of using the Google Docs Edit menu to perform those operations, as the latter doesn’t seem to work for pasting data from different applications into Google Docs. You no longer have a single computer as a choke point for data entry; multiple people can add data to a spreadsheet at the same time, and Google Docs will coordinate data entry so that nothing is lost. And if you save the spreadsheet data from steps 3 and 4 as separate files, you’ll have backup copies of the original data as well.

For those who aren’t comfortable with working with spreadsheets, Google Docs lets you set up a “Form” to let anyone add data to a Google Docs spreadsheet directly; however, this increases the chances of coordinate data entry error.

6. Now that you have all the data centralized in Google Docs, you have lots of flexibility in how you can handle it:

  • Export the data in CSV format, and you can then import it into any GIS program that supports CSV data. If your GIS program doesn’t, use MapWindow to convert your CSV file into shapefile format first.
  • Unlike shapefile attribute tables, where adding/removing/re-ordering attribute data columns can be a pain, you can easily perform those operations in Google Docs and then re-export the data in CSV format.
  • Convert the data directly into a continuously-updated KML network link for display in Google Earth or Maps using Google’s Spreadsheet Mapper tool.
  • Use any of Google Docs built-in tools to analyze/plot/sort/visualize data, including their way-cool Fusion Tables.
  • And I’m sure there are more options I haven’t thought of.

Know an alternate approach? Have any additional ideas?  I welcome your links and suggestions in the Comments section below.




Removing Time Data Out Of A GPX Or KML File To Make It Work Right In Google Earth

In the process of writing yesterday’s post on Garmin Basecamp, I found an annoying flaw on how Google Earth handles GPX files. In a recent GPS talk I gave, I surprised some people when I told them that Google Earth can open some GPS-related formats like GPX, LOC and others directly; you just need to select the type of files you want to open with the drop-down in the lower-right corner:

open_gpx

But if the waypoints in GPX files come time-stamped, either with the time you created them in the field or in a program, Google Earth assumes that you want to use this time-related data, and brings up a time slider in the upper-left-hand corner:

timeslider

The first time you open the file, the time slider will run from start to finish, with waypoints popping up and disappearing as the time indicator hits their creation time. You only see all the waypoints when the time slider has run all the way through to the end. Very annoying.

But it gets worse. If you uncheck the GPS data box in the Places pane to hide the data, then check it again, you’ll see nothing at all except the time slider:

timeslider1

Hitting the play button on the time slider will make the waypoints appear and disappear quickly, and at the end the only waypoint visible will be the last one created; the time slider will look like this:

timeslider2

To see all the waypoints, you’ll need to move the “start-time-extent” slider all the way to the left:

timeslider3

Same behavior if you save the data permanently to “My Places”. This is pretty retarded behavior; I hope Google adds the option to turn off time-related data display when it’s not wanted. Until then, I banged together a simple Windows-only program called GPXTimeStripper that will remove all time-related data from a GPX file (KML files, too, although this may not work in every case).  Download the file at this link; it’s a zipped stand-alone executable. Run the program (won’t win any interface awards):

Click on the main button, choose the GPX or KML file you want to process, and the program will remove the time data from the file, and save it with “_TS” appended to the filename. You’ll get a pop-up box with the name and location of the new file, which should always be the same location as the input file.  If the pop-up becomes annoying (which it will), check the box in the lower-left-hand corner to turn it off. Help button takes you to this page; Exit does what you’d expect.

No real checks for overwriting older files, and may not work on every file correctly (report bugs). Use at your own risk. BTW,  Google, would it kill you to have KML files created in Google Earth terminate in CR-LF instead of just LF?  It would simplify the job of reading them in correctly.