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Archive for the 'altitude' Category

Measure Distances, Get Elevation Profiles With Survey

Application Name: Survey

Description: Distance and elevation profile tool

Publisher’s website: sys-irap

Cost: Free (ad-supported)

Version/date reviewed: v.0.7.3  /  6-23-11

Phone/OS: Droid X / Android 2.3

survey_qr

Android Market (mobile app only)
Android Market (browser)


The Survey app is an odd mix of different functions, some of which work well and are useful, others less so.

survey_menu

Start up the app, and get three options: Measure, Short distance, and Long distance.

measure

“Measure” brings up the view from your camera (not visible in the screenshot above), along with a graduated on-screen scale and slider. The idea here is that if you know the distance to an object, you can set it using the slider, and the scale will adjust to measure the true size. Not really sure how useful this is, as it only works out to a distance of 5 meters max, and fairly small sizes. Seems to me it would be easier just to pull out a tape measure.

short_distance

The “Short distance” option brings up another camera view, and a superimposed ground line (red) and ground mesh. The idea here is that if you’ve entered the camera’s height above the ground in the Settings section, and if you put the ground line at the base of an object at the same ground level as you, you can determine the distance to the object, and use the vertical scale to determine the height. It works, sort of, but only to about a distance of 75-80 meters, and not very accurately at that. The Smart Measure app works in a similar fashion, but is easier to use and is marginally more accurate.

survey_1

 

The “Long distance” function is substantially more useful. Select this option, and you’ll get a Google Maps view with your current GPS location plotted as a base location. You can tap and drag this icon to set a different base location; unfortunately, there doesn’t seem to be an easy way to reset it to your current GPS location without backing out of this screen. The icon control at top left toggle between Google Maps/Satellite views (right icon), while the one at right centers the view on the current base location.

survey_2

A long press on a different location on the map creates a “survey point” at that location, marked with a camera icon. Press the “Survey” button at the bottom …

survey_3

… and get coordinates/elevations for base location and survey point, and the distance from the base point to the survey point. “G.H.” stands for “ground height”, and is determined by GPS for the base location, and always set to 0 for the survey point. You can adjust the ground height for either location with the button controls to the right.

point1

Tap on the camera icon, and get an augmented reality view through your camera, with the arrow telling you which direction you need to rotate the camera to have it oriented towards the survey point.

point2

When oriented correctly, the survey point will show up as a blue dot, labeled with the distance.

profile

Tap the other icon from the map screen, and get a plot of elevation from the base location to the survey point in orange. It’s not clear from the app what the green and red lines are; I believe they’re elevation plots and direct point-to-point sight lines that include the curvature of the earth’s surface, but I’m not sure.

Other issues: This app really needs better documentation; it’s not entirely clear how some of these functions work. The app description also implies that you can take geotagged camera shots of various screen views, but I couldn’t figure out how to get that to work.

Final thoughts: There’s the kernel of a good app here, and it’s worth taking a look at. But I prefer Smart Measure for distance/height measurements, and AltitudeProfiler for elevation profiles (though the latter has data download limits).




Graphic Local Elevation Displays With AltitudeProfiler

Application Name: AltitudeProfiler

Description: Displays elevation profile graph in one compass direction, graphic display in all directions.

Publisher’s website: AndroidPit

Cost: Free, but with daily data limit; paid version gives you data priority, and supports the program.

Version/date reviewed: v.1.02  /  2-28-11

Phone/OS: Droid X / Android 2.2

ap_qr

Android Market (mobile app only)
Android Market (browser)


Altitude Profiler downloads local elevation data, and plots/displays it in several different ways.

ap_main

Main screen displays local coordinate data and heading at the top. In the data box are:

  • True heading (not magnetic – yay!)
  • Magnetic declination at your location (?N)
  • The pitch angle and percentage slope (“/”); lay the phone flat on a surface to get its slope.
  • The view rotation angle (“R”), showing the twist angle of the phone
  • Latitude, longitude and elevation at your current location.

The slider sets the distance over which elevation data will be downloaded and displayed. Default is 6 km, and unless you have a really good reason, you should leave it there, or set it even lower. While the app lets you select a distance up to 200 km, this will involve downloading lots of data, and the app developer is paying for this (not to mention your own data download time and costs).

The 6 buttons in the lower part access various data and function screens.

ap_graph

The first button shows you the elevation profile in the direction you’re facing, for the specified distance. Green vertical lines marked the locations of highest and lowest elevation in the profile.Your current position is plotted in a Google Maps view in the lower half. Move the slider to the right …

ap_points

… and the map scrolls to the corresponding position. Markers are plotted every 1 km.

ap_colors

The second button brings up a 360-degree graphic representation of slopes in every direction; the display rotates with your heading. Reddish colors are up-slope, while greens are down, and the intensity reflects the steepness of the slope.

ap_least

The third button brings up this odd display, sort of similar to the previous one in intent. Here, it’s displaying the “difficulty of travel” in every direction; the fastest way to travel is to move in the direction with the minimal amount of yellow overlay (here, W is the easiest path, with SE a close second).

ap_airplane

Fourth button brings up an augmented reality view, with an airplane-like HUD overlaying a camera view (which you can’t see due to the limitations of screenshots). Heading, roll and pitch are displayed. IMO, the least successful and useful screen.

ap_map

Fifth button brings up a Google Maps view, with your current location plotted as the starting point. Scroll the map in any direction …

ap_scroll

… and see a line of points plotted from your original location to a new one. Press the middle button at the bottom (the square with the zig-zag in it) …

ap_local

… and see the elevation profile over that plotted line of points.

ap_scrolled

If you scroll the map to another point, and press the “select” button at the bottom, the center of the map will be designated as the start of a new elevation profile, and marked in red; just scroll the map again to set the end point. This way, you can find elevation profiles anywhere, not just from your current location. Pressing the “GPS” button will bring up back to your current location.

ap_settings

Final button brings up a panel to turn the GPS on/off (toggle the top button), and set the distance units to miles or km (toggle the bottom button).

Other issues: Lot of mixed comments on the Android Market on this app; some people complain about its interface, while others couldn’t get it to work. I didn’t have any issues with the interface, and it worked fine on my Droid X running Froyo.

Final thoughts: I reviewed an app called Elevation and Sea Depth a while back that offered similar functionality. While AltitudeProfiler doesn’t do sea depths, it offers a better display and more options for terrestrial elevation profiles. Unless you absolutely need the sea depth data, I’d recommend AltitudeProfiler as the superior app.




Horizon Profiles With HeyWhatsThat

Application Name: HeyWhatsThat

Description: Mobile-enhanced web app that shows the horizon line at your location, and identifies peaks

Publisher’s website: HeyWhatsThat

Cost: Free

Version/date reviewed: NA; 2-27-11

Phone/OS: Droid X / Android 2.2

Mobile web app

Main website (for desktop PCs)


This isn’t technically an Android app, as it will also work on the iPhone (for those behind the curve), but the HeyWhatsThat website has a mobile version that will show you the horizon line from your current location, with named peaks identified. Go to the mobile website address (m.heywt.com):

heywt_main

If you haven’t gotten a GPS fix recently, tap on “Update my location”, and it will fire up your GPS to get your current coordinates. Then tap on “Show me the view from here” …

heywt_address

The app will show you the coordinates it’s using for the calculation, and the nearest reverse-geocoded address. While the app says it may take up to 2 minutes to generate the horizon view, I’ve usually gotten the results in about 30 seconds or less …

heywt_panorama

The site comes up in Panorama view, with peaks identified on the horizon view with red triangles. Tapping on the single arrow buttons moves the line cursor from one peak to the next, with the name/bearing/distance/altitude given for each one. Tapping on the double arrow scrolls the panorama view to the next part of the horizon. Panorama locations are saved by the website, so that you can pull them up again instantly with the “A View I’ve Requested Before” option from the main screen. By default, it’s saved with the address as the label, but you can rename it to whatever you want using the Rename function at the bottom; you can also remove a saved location there as well.

heywt_list

Tapping on the List tab brings up a list of all the peak summits visible in your area; the app takes into account blockage by terrain, but not vegetation, buildings or atmospheric conditions. Tap on a peak in the list, and you’ll be returned to the panorama view with that peak selected.

heywt_details

The Details tab brings up information about your current position, and the panorama view. In the view above, the vertical relief is significantly exaggerated (7.7x) so that you can identify peaks more clearly. Unfortunately, the site gives magnetic bearings instead of true bearings, but it also conveniently gives you the magnetic declination here, so that you can manually correct for it. The link for a web view is nice, but it’s not an active link, so you can’t select it, or copy/paste it for notes,

How does this compare with Peak.AR, another app for identifying peaks on the horizon? Peak.AR is certainly more interactive and visually striking; you get peaks superimposed on a camera view, and the view changes as you rotate the camera. However, it identifies all peaks in a specific direction, and doesn’t calculate which ones are and aren’t visible from your location. And, as I’ve posted about, the older version of Peak.AR (which I vastly prefer) has been superseded by a newer version which I’m not crazy about. I use to use Peak.AR primarily, but even with its limitations, I find HeyWhatsThat makes it easier to figure out which peak I’m looking at.

The author of HeyWhatsThat has indicated that he’s working on an Android-specific app that will take advantage of the built-in compass, and change the view depending on which direction you’re looking in. There’s a test/sample version of the app available in .apk format here; it shows only sample views from a few specific locations, but the views change as you rotate the camera. If you download the test app, choose a location using the “Surprise me” option, then tap on the “Off” text in the view to turn on the compass.




Directional Elevation And Sea Depth Profiles For Android

Application Name: Elevation and Sea Depth

Description: Shows the elevation profile (or sea depth) in the direction you’re facing.

Publisher’s website: Binary Solutions

Cost: Free (ad-supported)

Version/date reviewed: v.1.2.3  /  10-31-10

Phone/OS: Droid X / Android 2.2

esd_qr

Android Market link (mobile app only)
Android Market link (browser)


The Elevation and Sea Depth app displays the elevation profile for 5 km ahead of you, or the sea depth if you’re at see. It specifies a 100m resolution for the elevation data, so I assume it’s using SRTM-90 data from NASA, which is fairly high quality; not sure about the source of its sea depth data. Since it queries a web database, you’ll need to have an Internet connection active to access the web data.

To use the app, you’ll need to lay your phone flat on a surface, and wait for it to get a good GPS position fix for your current location. It also only works in landscape mode (Figure 1):

esd1

Profile is plotted with your location at the left, out to 5000 meters (5 km) at right. Also displayed are your current GPS location (left); your GPS elevation (which can be off substantially) and your elevation from web data; and the current orientation of your phone and speed. The angular resolution for elevation profiles is 15 degrees, so while the phone is pointed at the 328-degree orientation, the elevation profile is given for the 330-degree orientation. Turn the phone to another orientation, and the display updates quickly with the new orientation and elevation profile (Figure 2):

esd2

Other Issues: Program worked fine; no crashes or force-close. I wish they would specify the exact data source, especially for the sea depth data. Elevation profiles seemed to reflect reality, though my neighborhood is so hilly that it’s tough to say that with 100% certainty.

Final thoughts: Seems to work as advertised. Didn’t have a chance to test the sea depth feature, and I’d be leery of using it for marine navigation purposes. But for hiking/biking, it has a permanent spot on my Android unit; it’s very useful to know what to expect in elevation changes in front of you. Recommended.