Now that we’re moving into the more active part of hurricane season, Stormpulse is a great site to monitor for information about current and past storms, satellite imagery, and current conditions and forecasts for US areas that are likely to be affected by hurricane activity.
Archive for July, 2007 Page 3 of 5
Locr is a web album site oriented around geographic location, where you can upload geotagged photos, share them, and have them display in an album or on a map interface. Basic accounts are free, and while I assume that premium accounts will be available for a price at some point, I can’t seem to find any mention of that on the site. Geotagging can be done with separate software called “locr GPS Photo”; the software is free, and available for download even without registering for the site. Make sure you download the PDF manual as well, as you’ll probably need it. You can either manually geotag a photo using a Google Maps interface, or use GPS data to assign geotags. Here’s the basic interface:
The software does work, but it’s not without quirks, particularly for automatic geotagging with GPS data.
1. One of the biggest pains of locr is that it doesn’t accept standard GPX files for geotagging - it requires nmea files. You can convert GPX to nmea using GPSBabel, and the following procedure from the help file:
Converting gpx file into nmea format
- Double-click the “GPSBabelGUI.exe” file to start GPSBabel.
- In the GPSBabel window select the “Format” of the input file: “GPX XML”.
- Click the “Start the file open dialog” button and select the respective folder and input file.
- As “Output Format” select “NMEA 0183 sentences”.
- Click the “Start the file save dialog” button to determine the output folder. Enter the file name. Do not forget the “.nmea” file extension!
- In the menu click “Options” and select the “Filter” command (or click the “Filter” button).
- In the “Filter” window activate the “GPS fixes” check box and select “pps” as option. Click “OK”.
- Then click the “Let´s go” button.
The gpx file will be saved in the nmea format, which then can be opened in the GPS Photo software.
Make sure you have the latest version of GPSBabel and the GPSBabelGUI. And be prepared for problems. In particular, if any of your GPX trackpoints don’t have a timestamp, GPSBabel won’t be able to create the nmea file, and will generate an error message. You’ll have to open the GPX file in a text editor, manually delete the trackpoints with no timestamp, then save the file as a new GPX file before using GPSBabel to convert it to the nmea format. Hopefully, locr will recognize the need to accept the standard GPX format in their program, and add it as an option sometime soon.
2. Sometimes, it won’t tag a photo in a series; if that happens, click on the “Clear EXIF location tags”, and that may be enough to get it to work.
3. The geographic location is written in the EXIF tag, but some programs (like Picasa) can’t read EXIF tags modified by locr. 9/3/08: I’ve heard this is no longer an issue. The problem apparently results from a problem that Picasa has reading the GPSVersionTag created by locr. There’s a fix for this: download EXIFTool, a free command-line utility for EXIF tags, re-name the executable file to exiftool.exe, copy it to the directory with the photos in it, and from the command line execute the following command:
exiftool -GPSVersionID=0.0.2.2 -overwrite_original *.jpg
This will re-write the GPSVersionID tag to one that Picasa recognizes, and Picasa will then pick up the geotagging information in those photos.
Addendum: Check this follow-up post for a GUI for EXIFTool.
On the plus side, manual photo geotagging is fairly painless - zoom in to the area in a Google Maps interface, select the photo, and click on the “Manual geotagging” button to tag it. You can also enter an address into a search box, and have that be automatically geocoded for you. You can then move the marker manually after the initial tagging to fine-tune its position. Select a group of photos that have been geotagged, and click on the “Show photos on map” button, and their positions will be indicated on the Google Map. You can also select a set of photos, and create a KML file of thumbnails for display in Google Earth with the push of a button.
If locr would accept GPX files, not have the occasional tagging glitch, and write the GPSVersionID tag properly, it would be pretty awesome. Even with those faults, though, locr is still pretty good, especially at the price.
Ogle Earth posts about ITNConv, a program that converts from one GPS format to another. It opens:
- Autoroute Express (.axe, .axg)
- Streets & Trips (.est)
- MapPoint (.ptm)
- MapSource (.gdb, .mps)
- TomTom 3, 5 & 6, Go, Rider, One (.itn, .ov2)
- Navigon MN|4, MN|5 & MN|6 (.rte)
- Destinator PN (.dat)
- Marco Polo, Falk Navigator, Motorrad Tourenplaner & OnRoute (.bcr)
- GPS eXchange (.gpx)
- GPX MapSource (.gpx)
- Garmin PCX5 (CartoExploreur) (.rte)
- Magellan SD (Meridian et eXplorist) (.rte, .upt)
- ViaMichelin (.xvm)
- IGN Rando (.rdn)
- OziExplorer (.rte)
- OziExplorer CE (.rt2)
- Google Earth (.kml)
- CSV (Longitude,Latitude,Comments)
And writes in:
- Autoroute Express (.axe) (Version 2004 and higher)
- TomTom 3, 5 & 6, Go, Rider, One (.itn)
- Navigon MN|4, MN|5 & MN|6 (.rte)
- Destinator PN (.dat)
- Marco Polo, Falk Navigator, Motorrad Tourenplaner & OnRoute (.bcr)
- GPS eXchange (.gpx)
- GPX MapSource (.gpx)
- Garmin PCX5 (CartoExploreur) (.rte)
- Magellan SD (Meridian et eXplorist) (.rte)
- ViaMichelin (.xvm)
- IGN Rando (.rdn)
- OziExplorer (.rte)
- OziExplorer CE (.rt2)
- XML Location (.loc)
- Google Earth (.kml)
- CSV (Longitude,Latitude,Comments)
Not as many as GPSBabel, but it does a few that GPSBabel doesn’t, and the interface is a bit easier to handle:
It’s very much point-oriented, though. If you convert a GPX file with several tracks into a KML file, it will connect the endpoints of successive tracks to create one single, long track. Similarly, if you convert a set of waypoints into KML, it will connect all the points sequentially into a single long track (but you can always turn the track off in Google Earth, or delete it entirely). GPSBabel handles tracks better.
One nice touch is the built-in editor that loads the points into a Google Maps interface, where you can re-label them, move them around, add or delete points, search, find get directions, etc.. You can even create a set of points, and then save them in one of the supported formats:
Note: The website is in French, but the program itself is in English. Look for the download at the left under “Telechargement”, or at the bottom labeled “Télécharger la version Windows“.
There are a fair number of programs that not only embed geographic data from a GPS file into a photo’s EXIF header, but also have a host of other features as well. While I’ll be posting about some of those shortly, I thought I’d start out with two more modest programs that don’t do much more than geotag the photos.
More after the fold …
Continue reading ‘GPS Photo GeoTagging I - Two Simple Solutions’
The last post had the 8 most popular posts on the blog over the past six months, but they aren’t necessarily the ones I liked the best. Here are five posts I think I did a good job on:
5. How to easily create good-looking map relief shading with 3DEM
4. Creating animated viewsheds with MicroDEM
3. Converting E00 vector data to shapefile format with free software
2. Determining the effect of GPS satellite signal blockage by terrain on GPS accuracy
And, number one with a bullet …
Today, this blog turns 6 months old; thanks for stopping by! I’m still nowhere near running out of material, and I’m not burned out yet (though some days are kinda tough). Here’s a list of the 8 most popular posts/series on the blog over its history, based on number of visits:
8. Importing/Exporting GPS Data To/From GIS
7. Exporting Shapefiles To Google Earth
4. Converting KML Files To Shapefiles
3. Re-projecting Shapefiles From One Coordinate System To Another
2. Convenient ways to handle data in Garmin GPS units with microSD cards
And, easily number one ….
(Why not a top ten? Because everyone else does top tens …)
Using Picasa, PicasaWeb or iTag to geotag your photos through Google Earth (or Google Maps) is fine for the occasional photo, or for photos from the past where you don’t have specific location data, i.e. latitude and longitude. But if you’re going to be geotagging a lot of photos in the future, doing it manually will turn into a chore very quickly. There’s a way to simplify that task: Take location data from a GPS unit, and then embed it into your photo’s EXIF header or IPTC tags with software that automates the process. There are a lot of free and cheap programs that let you do that, and I’ll be covering many of the Windows options in upcoming posts. First, though, I want to go over some of the basics of equipment and data.
Equipment: Some day, most cameras may come with GPS capabilities built-in, so that they can automatically geotag your photos as you take them. But I’ve heard of only two cameras with built-in GPS released to date: the Navman iCN750 (discontinued), and the Ricoh Pro G3 GPS Camera, a two-year-old 3-megapixel model. So for now, the only reasonable choice is to use a handheld GPS receiver that can log your position continuously as a function of time, save that data, and then upload it to your computer (typically in GPX format).
Most handheld GPS units can do all of this, with the cheapest units running less than a hundred dollars. If you don’t need a large, handheld GPS receiver with all its features (data screen, input, maps, etc.), another option is to buy a simple GPS datalogger, like the Sony GPSCS1KA or Sony GPS-CS1
Data: You need to have both position and time data stored by the GPS units in order to geotag the photos,. The position data is obviously needed for the geotagging, but the time data plays a critical part as well. The software programs that I’ll be posting about match up the time you take your photo with the location the GPS data says you were at for that time, and then embed that time-specific location data in the photographs. Dataloggers will normally save both the location and time together automatically, but handheld GPS units may require you to specify that both time and position data be recorded in a GPS tracklog. Handheld units often let you specify whether your position is recorded continuously based on distance, time, or some combination of the two.
There’s another catch: some GPS units (like my Garmin) strip out the time data if you save the track in a separate tracklog, separate from the active track. So if you save a track in these units, make sure you don’t clear out the active track as well, or else you’ll have no way to synchronize your position with the time you took a photo. Found this out rather annoyingly after having taken a whole bunch of photos, saving the track, and then discovering that all the time data was gone. The newer Garmin x-series models let you log time and position data continuously to a GPX file on their microSD memory cards, bypassing the need to manage track data completely (and letting you record literally months worth of position and time data on a single microSD card).
You should also check to make sure that your camera is set to the same time as your GPS unit; if the camera’s time is off, or in a different time zone, that can complicate the process of matching up the GPS track time with the time the photo was taken. Many programs come with the ability to adjust for such a time difference, but it will make life a lot easier if you make sure they’re in time synch right from the start. GPS track times are recorded in UTC (aka Greenwich Mean Time), and while most programs can correct for the difference, some have problems with that correction.
Uploading the data to your computer from your GPS is usually straightforward; if the software that came with your GPS can’t take track data and save it in GPX format, a free program like EasyGPS or GPS TrackMaker does a great job.
Summing up: to automate geotagging your photos with GPS, you’ll need a GPS receiver that can log both your position and time on a continuous basis, and then upload the data to your computer in GPX format, where it can be synchronized with your photos based on time.
Ogle Earth has done posts on using Picasa to geotag (aka geocode) photos in both the stand-alone version of Picasa, and online in PicasaWeb albums. There are a fair number of other stand-alone programs for geotagging photos in a wide variety of ways, many of which include other useful features (like inserting the photos into Google Earth or Google Maps). Over the next few weeks, I plan to review a fair number of these programs on this blog.
First up is iTag, an IPTC tag installer. Its principal function is to add title, description and keyword tags to photos, but it does have some geotagging capabilities. iTag opens entire folders with pictures, and displays their contents in thumbnail format:
If your photos are already geocoded, iTag can create placemarks with a photo thumbnail bubble in Google Earth, though this can take a while depending on how large the photo size is:
You can save the placemark from Google Earth, but iTag also lets you create a KMZ file with the photo (or photos) embedded directly in the file, or linked to an internal or external location.
Geotagging a photo or group of photos is a multi-step process. You need to first create a placemark at the desired location in Google Earth. iTag’s default geotagging process is to take KML placemark data copied into the Window’s clipboard (right-click on the placemark and choose Copy), and use the geographic data embedded in that to geotag the photos. You also have the option of using a saved KML placemark file to geotag the photos. I prefer Picasa’s method of geocoding the position directly in Google Earth by selecting the photo in Picasa and then choosing the position with a cursor in Google Earth, but there may be occasions when iTag’s placemark process might be more convenient.
iTag lets you copy EXIF GPS data to the IPTC tags and vice versa, and also erase the geographic data completely from the photo. It also can convert GPX waypoint files to KML, so that you can use individual GPS points to geotag your pictures (but there are better ways to do this that will be covered in future posts).
iTag is a convenient way to apply descriptive tags and keywords to a photo or group of photos, better than the Picasa IMO because that’s all it does. The geotagging capabilities are a convenient bonus, but here I think Picasa is easier to use in most (if not all) cases.
