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Archive for the 'height' 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

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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.

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

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“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.

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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.

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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 …

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… 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.

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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.

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

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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).




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):

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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” …

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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.




GeoCam – Additional Features

Yesterday’s review of the Android app GeoCam  concentrated on its main features, measuring/recording position and orientation info. But it has a few cool additional features as well.

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In the lower right hand corner of the main display are flag and map icons. Tap on the flag …

Name

… and enter a name for that location; the position is now stored under that name.

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Go to the Geo tab of the Settings section, and tap on the multi-flag icon to get options for your saved “flags”.

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“View on Maps” displays the flag markers in a Google Maps view; you also get this by tapping on the Map icon on the main screen.

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Tap on a flag to get its name.

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The “View List” option lets you see all your saved flags; a long press on any item in the list brings up the option to delete them. The single flag listing in settings has the same function as the Flag icon on the main screen, to give you the option to record your current position.

flag

Where it gets really cool is that if you point your phone in the general direction of a flag, you’ll see its name and distance on the augmented reality (AR) display (note: you’d normally see the camera view as well, but screenshots can’t capture camera views, so you just see a gray background above).

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Under the “Geo” tab in settings, there’s also a compass icon; tap on that, and get options to measure distance and height. Unlike apps such as Smart Measure, which require that the object you’re measuring be on a plain, level surface at the same elevation as you, GeoCam uses GPS position data to get distance and height by triangulation. For distance, select the option, center the object in your display, and tap the display center. Then shift over sideways as long a distance as you can, center the object again, and tap the center. GeoCam uses the two GPS positions, and the two orientations of the phone when pointing at the object, to estimate the distance from the midpoint of the measurements to the object by triangulation.

The accuracy will depend strongly on how precisely you center the object, how far apart the two measurements are made, how far away the object is, and what your current GPS error is; the app won’t let you make this measurement if GPS error is larger than 10m. At short distances on level surfaces, Smart Measure is much more accurate, but its accuracy decreases rapidly as the object gets further away, and doesn’t work well at all on uneven surfaces. I tried multiple distance measurements with GeoCam, and with care you can get accuracy to within 5% or less of the actual value for objects about 50 meters or further away.

Once you have a distance to an object, you can use GeoCam’s Height function to roughly measure how tall it is from base to top. Select the Height option and enter the distance to the object in meters. You’ll then be prompted to point first to the base of the object and tap the screen, then the top of the object and tap; from the distance and angle info, GeoCam will calculate height. Didn’t try this too many times, and didn’t have good height info for my test objects in any case, but the values were at least within the ballpark of what I would have expected.

The author keeps adding new features, so it will be tough to keep this review up to date. One promised new feature will be the ability to export the flag positions as a KML file for use in Google Earth. But I’d love to see an import option for KML or GPX waypoints, so that you can load them in for use in the augmented reality mode. The ability to add a flag marker with a long press on the Google Maps view could also be useful.

In any case, given the current price (free), this is a must-have app, and the paid version is definitely worth a look as well.




Identify The Peaks In Your Area – New (And Not As Good) School

Application Name: Peak.AR

Description: Maps peaks close to you, and identifies them in an augmented reality view.

Publisher’s website: Peak.Ar

Cost: Free

Version/date reviewed: v.2.0.2  /  12-5-10

Phone/OS: Droid X / Android 2.2

Peak.ar_qr

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


So yesterday, I reviewed the older version of Peak.AR, a really cool app that identifies hill/mountain peaks in an augmented reality (AR) view. Today, I’m looking at the newer version, or more specifically why you should get the older version and skip the newer one.

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Figure 1: The older version displays all the peaks in all directions …

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Figure 2: … while the new one only displays peaks in the direction the phone is pointed. It also only displays those peaks within a specified distance range, and has oddball range circles beyond that point that change as you change the direction you’re pointing.

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Figure 3: You set the distance range with a hidden control at right, that pops up when you tap there. Drag to change the distance range at which peaks are displayed; you have no control over the distance ranges, but have to use the presets.

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Figure 4: In augmented reality mode, the older version had a slider that let you set the distance range for viewing peaks. The maximum number of peaks visible in AR view is 10, so it filtered out smaller/less-visible peaks to get the displayed peak number down to no more than 10. It also had a “radar” view that showed the direction you’re pointing, as well as the peak positions in all directions. Note: my screenshot app doesn’t show the camera view; in real life, you’d see the peaks superimposed on the actual camera display.

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Figure 5: The new version of Peak.AR only displays peaks within the distance range you’ve set, but doesn’t show what that distance range is; you have to tap on the right side again to bring up that control and see what the distance range is. In principle, this will let you identify any peak you can see, just by changing the distance range until it shows up in the AR view. In practice, this is a pain in the neck to use. You’re also most likely only interested in the most prominent peaks, and this approach makes those more difficult to identify. The radar view is also sorely missed. Finally, peaks have a tendency to disappear/appear from view with even a small 1-2 degree shift in your phone’s orientation.

Other issues: None.

Final thoughts:

I strongly urge you to try the older version of Peak.AR first – it’s a lot simpler to use, and works a lot better IMO. You can then try updating the newer version, to see if you like it. But I’m guessing that you’ll quickly uninstall the new version, and go back to the old one when you get a chance.




Identify The Peaks In Your Area – Old School

Application Name: Peak.AR (older version)

Description: Maps peaks close to you, and identifies them in an augmented reality view.

Publisher’s website: Peak.Ar

Cost: Free

Version/date reviewed: v.1.04  /  12-5-10

Phone/OS: Droid X / Android 2.2

Old version no longer available on Android Market, but you can download the .apk file for the old version from the Peak.Ar FAQ page, and install it directly on your phone. Just don’t update it unless you really want the new version (and I don’t think you do).


This is going to be a bit odd – I’ll be reviewing the same app twice over the next few days. Today’s review is of the older version of Peak.AR, which is no longer on the Android Market, but the .apk program file for this older version. can be downloaded and installed directly on most Android phones as long as you have Unknown sources enabled in the Applications setting for your phone. Why review two versions? Because I really like the old one, and have some reservations about the new one.

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Figure 1: Start up the Peak.AR app, and it gets your GPS location, loads in a database of local peaks, and plots those peaks in a Google Maps interface that you can scroll through; the compass at upper left points towards true north.

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Figure 2: Tap on a peak in the map view, and get an info page with the name, location, height and distance.

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Figure 3: The real magic happens when you hold the phone horizontally; the locations of peaks are plotted in an augmented reality (AR) camera view, so you can line up the peaks with the actual view (which the screen capture can’t show). The slider at the bottom lets you set the distance range for viewing peaks. The radar at lower left shows the direction you’re pointing in, and the number of peaks within the distance range you’ve set. The app only shows a maximum of 10 peaks in the view to keep the app from slowing down too much, and filters out shorter/less-visible peaks from the AR view to keep within that limit of 10. Tap on a peak in the AR view, and you’ll get an info page like the one in Figure 2.

peak.ar.1.3

Figure 4: Here’s a screen shot from the web app page, with the camera view visible, to give you a feeling for how it actually looks.

Other issues: Earlier versions used magnetic north instead of true north, which could result in a considerable misalignment of the labeled peak with the true peak in the augmented reality view. The final release of the older version seems to have fixed that.

Final thoughts:

This older version of Peak.AR is two tons of awesome in a one-ton bag; a must-have app for showing off what your Android phone can do. Oh yeah, there’s also an iPhone version available.




Measure Distances, Heights And Direction With Your Android Phone Using Smart Measure

Application Name: Smart Measure

Description: Measure object distance, height and direction.

Publisher’s website: Android Boy

Cost: Free

Version/date reviewed: v.1.1.1  /  9-6-10

Phone/OS: Droid X / Android 2.1

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


Smart Measure uses your Android’s orientation sensor, camera view and some simple trigonometry to figure out how far away and in what direction and object is. If you read the comments on the Android Market about this app, you’ll see that some people think it’s great, while others complain that it doesn’t work at all. I had problems getting it to work correctly, but ultimately managed to get reasonable results. In order to get it to work, you have to understand its limitations, and also configure it correctly for your unit.

 

The program starts off with a simple diagram explaining how it works; by using the height of the camera above the ground, and the angle you need to tilt the unit so that a crosshair touches the base of the object you’re measuring, it can calculate the distance to the object:

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Then, using the distance and the angle you have to tip the camera up, it can calculate an object’s height:

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But in order to get an accurate measurement, you need the following:

– A constant height of the camera above ground; you need to measure this value (in meters), and input it as a constant into the program. But you also have to make sure that when you tilt the camera to measure the angle, you also don’t change its height, as this will throw the measurement off. For me, the best approach was to have the camera lens at eye level, and then twist my wrists to rotate the camera while keeping the camera lens at the same height. This takes some practice, as my natural inclination was to lower or raise the camera as I tilted it up or down.

– An accurate angular measurement. Smart Measure has a default “vertical” angle of 88 degrees, but this resulted in horribly inaccurate results. There’s a built-in calibration mode, where you place your camera against a known vertical surface and push a button, but this didn’t work for me – it kept complaining that the angle was too steep. You can also enter a “vertical” calibration angle manually, and this was the approach that worked for me – I finally wound up at 94 degrees vertical. But to get good results, you have to measure a distance manually using a tape measure, use Smart Measure to determine the distance, then adjust the calibration angle until Smart Measure’s value agrees with the actual distance. Once I did this, the distance measurements I got were fairly decent.

– Your feet and the base of the object need to be at the same level. For practical purposes, this means that you both should be on a flat, level surface.

– Maximum distance readout with Smart Measure was 80 meters, but at those distances, even a small shift in camera angle results in large measured distance changes. It seemed to me that  about 50 meters was the maximum distance at which you could expect to get  results that were even reasonably close, if not 100% accurate.

Once I had the unit calibrated and configured, using it was easy. Using the screen, point the crosshair at the base of the object you want a distance to, and press the “shutter” button at lower right to capture and freeze the distance measurement:

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You’ll get a “freeze-frame” of the capture shot in the upper-right corner. Here, the actual distance to the base of the wall was 5.05 meters, but since the capture was slightly short, this is pretty accurate.

Once you shoot the distance measurement, if you want the height, tap on the tree icon, tip the camera up so that the crosshair touches the top of the object, and press the “shutter” button again to freeze the height measurement:

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Actual height was 2.8 meters, so it’s a bit short, but still not too bad. Notice also that there’s a compass in the upper-left with a digital readout of the bearing; as best as I can tell, it’s reading the magnetic direction (which can be off from your true direction, often substantially; more on this in future posts).

Issues:

– One force-close, but  usually worked without incident.

– In compass, digital bearing is in small digits, and is obscured by graphic indicator when you’re point north.

– Magnetic bearing given, not true bearing.

– No way to save data; screen capture would be helpful.

Final thoughts:

If you calibrate it correctly, and keep in mind its limitations, Smart Measure is a quick and modestly accurate way to measure distances, heights and bearings of close objects (<50m distance). But it’s no substitute for a tape measure, or even a well-calibrated foot pace. Still, it has a permanent place in my Android phone’s toolbox.