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Archive for March, 2011 Page 2 of 2

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View GIS Shapefiles On Android With SHP Viewer

Published in GIS, map display and shapefile. 1 Comment

Application Name: SHP Viewer

Description: View GIS shapefiles on Android, query attributes.

Publisher’s website: nexti

Cost: Free

Version/date reviewed: v.1.03  /  3-8-11

Phone/OS: Droid X / Android 2.2

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

Note: Also requires the Adobe Air framework; Android Market link (mobile app) , Android Market link (browser).

There aren’t a lot of vector GIS data viewers currently available for Android; actually, as of the time of writing, I could only find one such app, SHP Viewer, reviewed here. After installing the app, copy the .shp, .shx and .dbf files to the “Maps” directory on your SD card; if the directory isn’t there, you’ll need to correct it. Shapefiles need to be in the geographic projection (latitude/longitude coordinates), WGS 84 datum (NAD 83 is close enough, as are many other modern datums).

shp_list

After copying the shapefiles over, and starting the app, you’ll need to press the “Refresh” button in the upper right to get them to show up in the file list (the home button at upper left exits the program). Tap on a shapefile in the list to select it.

shp_map_init

The initial view will be of the entire extent of the shapefile; you can zoom in either with the zoom control at right, or multi-touch pinch to zoom. Tap and drag to pan the map.

shp_map_zoom

SHP Viewer supports polygons, polylines and points; I’ve test it with all three, and it seems to work with all of them. Here, a polygon map is loaded. If you tap on a polygon shape …

shp_attributes

… you’ll get a popup window listing all the attribute values for that shapefile.

Other issues: Small shapefiles (< 1 MB) drew quite quickly. Tried a 13 MB polygon shapefile, and that was a bit slow to show up (20 seconds), but it did work. Then tried a 250 MB polygon shapefile, and crashed the app so completely I had to reboot. So don’t try shapefiles that are too large.

The app could really use two additional features:

  • GPS option, so that you can display your position on the shapefile map display
  • Thematic display, i.e. different colors or symbols depending on a shapefile attribute.

Final thoughts: Not a lot of choices yet for GIS data apps on Android, but they’re coming. For now, SHP Viewer is a reasonable stopgap.




Annotate A Google Maps View With DrawMap

Published in Google Maps and notes. 0 Comments

Application Name: DrawMap

Description: Capture a view in Google Maps, then draw markers/lines/shapes on it.

Publisher’s website: Young Hoon Park

Cost: Free

Version/date reviewed: v.1.01  /  3-1-11

Phone/OS: Droid X / Android 2.2

dm_qr

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

DrawMap lets you annotate a Google Maps view by drawing on it.

 

md_1

Scroll/zoom the Google Maps view to your desired area, then tap capture to save that view as a bitmap image.

md_2

The editing screen will pop up. Select the type of annotation you want to create at top; from left to right, they are:

marker

Marker (e.g. like a standard placemark): Tap and hold on the screen, then drag the placemark to your desired location.

segments

Line segments: Tap on multiple locations, and have straight lines drawn between those points.

freehand

Freehand line: Drag your finger on the screen to draw a freehand line.

circle

Shapes: Draw a circle, square or line on the map.

You may have noticed that the buttons at the bottom change, depending on what kind of feature you’re drawing.

markertypes

For markers, choose between three different types.

linesize

For line segments, freehand lines and shapes, you can choose the size of the line with the Width control (the three dots of increasing size). To change the size, tap and hold on the box, then drag left/right to decrease/increase size).

colors

All annotation types also let you set the color by tapping on the color wheel button at the bottom.

Two of the annotation types also have toggle switches:

  • Freehand: Toggle between drawing and erase mode. Erase wipes out any drawn features of any type, including markers.
  • Shapes: Toggle between circles, rectangles and lines.

save

Once you’re done, tap on the disk icon to save the image; you’ll see the name of the file and the save location at top. You’ll also have the option to share it immediately with other locations/services like email, Facebook, Dropbox, etc..

Other issues: An undo button would be an enormous help; as is, your only option to undo a feature is to erase it manually. A text box option would also be a really useful feature; handwriting text on the map is a pain. It would also be nice to have additional map options (terrain, satellite view).

Final thoughts: If it had a text option, it would be almost perfect, and hopefully that will be added soon. As is, it’s still the best Android map annotation program I’ve seen.




Graphic Local Elevation Displays With AltitudeProfiler

Published in altitude, compass, elevation, Google Maps and GPS. 1 Comment

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.




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