Adventures with SD cards in the field

We got some variable results with SD cards in some recent fieldwork – cameras not taking photos as regularly as possible, transfer rates not as advertised – and some research turned up even more disturbing news about SD cards and what to watch out for.

SD cards are cheap because they are fundamentally made of cheap, error-prone memory, and rely on a microprocessor in each card that manages the data and thus what your computer sees. This has huge security consequences. Watch the youtube video in the link.

There are hacked SD cards that are labelled at high capacities, will report a higher capacity when plugged into your computer, but actually have a fraction of that capacity available.

This post will be updated with tools and code for testing SD cards; am experimenting with a few different tools.

QGIS on an Android tablet

Running QGIS on an android phone worked just fine – but running QGIS on an Android tablet is going to be a lot more useful, with a larger screen. I summarised the steps of installing QGIS on a Galaxy Advance (I9070) in a previous post, under Gingerbread (2.3.6); since then, there have been some issues with QGIS breaking due to Ministro (supporting library) updates, so I went through the installation steps again, this time on an Asus TF300T running Jelly Bean 4.1.1.

Installation

  1. Enable “Allow installation of apps from unknown sources” – Settings|Security.
  2. Download the installer .apk (this download should  be fixed and up-to-date) and open it (on most Androids it will download to a “Downloads” directory, but may be elsewhere; you can just click to open the file from your file browser and it should start the installer).
  3. Run the installer and select ‘download and install’. 83 MB of data will get downloaded. Luckily, it is a resumable download – if it fails, you can start the process off again where you left off.
  4. Confirm that you want to install (standard Android dialogue) – takes about 2 minutes to finish this stage.
  5. Run QGIS: “Unpacking post-install data” … 10 seconds.
  6. QGIS requires a supporting service, available from the Play store “This application requires Ministro service. Would you like to install it?” Confirm and install Ministro II, only 523KB.
  7. Looks like it needs MORE libraries to run! “Qgis needs extra libraries to run. Do you want to download them now?” Confirm and install the QtCore libraries – a lot bigger at 31MB.

Does it work? Sort of …

Sure does … except for the Python plugins, which are not working, it does run and I’ve used it in the field a few times now. The version I’ve just installed, however, won’t let me select the panels to view, which means I can’t access the GPS connection panel to do live tracking. This really limits the utility, but one can pan, zoom and view maps.

Screenshot_2013-03-27-13-33-55Screenshot_2012-08-23-15-13-09 Screenshot_2012-08-23-15-22-14 Screenshot_2013-03-27-13-33-18

Tips and Tricks

  1. Export a QGIS project from your desktop into a single folder + .qgs file using the QConsolidate plugin, then transfer that consolidated folder + project file to the MicroSD card. This will gather all the rasters and vector files into one place for easy transport.
  2. Don’t work with high-resolution rasters unless you’re very, very patient; turn these off or remove them altogether. In the example above, the red ‘slope’ layer was a 25%-scale version of my original (which we just had to show us places we couldn’t fly low-level safely in the Cessna).

Acknowledgements

Thanks again to Marco Bernasocchi for porting and continuing to develop QGIS for Android – if it’s useful, you should really make a donation!

QGIS on an Android tablet

Running QGIS on an android phone worked just fine – but running QGIS on an Android tablet is going to be a lot more useful, with a larger screen. I summarised the steps of installing QGIS on a Galaxy Advance (I9070) in a previous post, under Gingerbread (2.3.6); since then, there have been some issues with QGIS breaking due to Ministro (supporting library) updates, so I went through the installation steps again, this time on an Asus TF300T running Jelly Bean 4.1.1.

Installation

  1. Enable “Allow installation of apps from unknown sources” – Settings|Security.
  2. Download the installer .apk (this download should  be fixed and up-to-date) and open it (on most Androids it will download to a “Downloads” directory, but may be elsewhere; you can just click to open the file from your file browser and it should start the installer).
  3. Run the installer and select ‘download and install’. 83 MB of data will get downloaded. Luckily, it is a resumable download – if it fails, you can start the process off again where you left off.
  4. Confirm that you want to install (standard Android dialogue) – takes about 2 minutes to finish this stage.
  5. Run QGIS: “Unpacking post-install data” … 10 seconds.
  6. QGIS requires a supporting service, available from the Play store “This application requires Ministro service. Would you like to install it?” Confirm and install Ministro II, only 523KB.
  7. Looks like it needs MORE libraries to run! “Qgis needs extra libraries to run. Do you want to download them now?” Confirm and install the QtCore libraries – a lot bigger at 31MB.

Does it work? Sort of …

Sure does … except for the Python plugins, which are not working, it does run and I’ve used it in the field a few times now. The version I’ve just installed, however, won’t let me select the panels to view, which means I can’t access the GPS connection panel to do live tracking. This really limits the utility, but one can pan, zoom and view maps.

Screenshot_2013-03-27-13-33-55Screenshot_2012-08-23-15-13-09 Screenshot_2012-08-23-15-22-14 Screenshot_2013-03-27-13-33-18

Tips and Tricks

  1. Export a QGIS project from your desktop into a single folder + .qgs file using the QConsolidate plugin, then transfer that consolidated folder + project file to the MicroSD card. This will gather all the rasters and vector files into one place for easy transport.
  2. Don’t work with high-resolution rasters unless you’re very, very patient; turn these off or remove them altogether. In the example above, the red ‘slope’ layer was a 25%-scale version of my original (which we just had to show us places we couldn’t fly low-level safely in the Cessna).

Acknowledgements

Thanks again to Marco Bernasocchi for porting and continuing to develop QGIS for Android – if it’s useful, you should really make a donation!

QGIS on Android phone: Installing

There is a more up-to-date version of this page detailing the installation on an Asus TF300T tablet here.

I decided to try out QGIS on my Samsung Galaxy Advance – a little 4-inch screen, but why not? I’d run through the same process on an Asus TF300 tablet previously (much larger screen and more appropriate for GIS use – but more on that later) and wanted to document how it went.

You’ll need an active and fast network connection – you’ll download a bit over 100MB of files during the installation. (For more screenshots and installation details see here from upande.com)

Steps:

  1. To install ensure you’ve selected “install from unknown sources” in the Settings;
  2. Download the installer .apk and open it (on most Androids it will download to a “Downloads” directory, but may be elsewhere; you can just click to open the file from your file browser and it should start the installer).
  3. Run the installer and select ‘download and install’. 83 MB of data will get downloaded. Luckily, it is a resumable download – if it fails, you can start the process off again where you left off.
  4. Confirm that you want to install (standard Android dialogue) – takes about 2 minutes to finish this stage.
  5. Run QGIS: “Unpacking post-install data” … 10 seconds.
  6. QGIS requires a supporting service, available from the Play store “This application requires Ministro service. Would you like to install it?” Confirm and install Ministro II, only 523KB.
  7. Looks like it needs MORE libraries to run! “Qgis needs extra libraries to run. Do you want to download them now?” Confirm and install the QtCore libraries – a lot bigger at 31MB.

Then QGIS just seems to run! Tough to use the little tiny buttons / menus, but workable. You can even use the GPS connection – took me a while to realise it was under View | Panels | GPS – click ‘connect’ on the panel after displaying it.

 

 

Troubleshooting install of QGIS in OSX

Yesterday afternoon I found I couldn’t run QGIS at all – it kept crashing on startup, whenever it got to the splash page “loading plugins” bit. I tried restarting without plugins running (/Applications/QGIS.app/Contents/MacOS/QGIS –noplugins) but it would still crash when I went to the “Manage Plugins …” menu option, so no chance of turning them off.

Running QGIS as the guest user worked fine – so I figured it probably wasn’t a problem with bad frameworks, the system or the app itself. Using AppCleaner to search for QGIS-related directories came up with a few things but deleting ’em didn’t help (it missed the .qgis hidden directory in the user folder).

So, to do a clean install or to remove potentially troublesome data (no need to delete QGIS itself), open a terminal session and enter:

rm ~/Library/Caches/org.qgis.*
rm ~/Library/Preferences/org.qgis.*
rm ~/Library/Saved\ Application\ State/org.qgis.*
rm -r ~/.qgis/

… and that should do the trick!

 

* in the past few days I installed qgsAffine and multiqml but not sure that’s the actual problem.