Once you’ve made a whole bunch of beautiful maps in QGIS, you can click the ‘Export as image’ button (or PDF) and save a version of the map to disk. Doing so for more than a few of these is really tedious – for example, if you’ve had to add or update elements of a layer that’s common to a set of maps, you have to go through about 12 clicks per map to save ’em.
The script below will loop through and export all of the layouts in the current project, writing a PNG file (change ‘outformat’ to JPG if you like) at 200DPI.
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.
Capacity, classes and speeds must be checked with real-world tests.
Sustained write and read speeds vary from advertised.
Actual size of the card must be measured, and checked for errors.
Cattle, sheep and goats from 1200 feet AGL. Nikon D3100, 35mm lens.
We’re about to start a livestock and wildlife census in the Serengeti ecosystem, and using a point photo count method (APS). This is the first time we’ll have used APS for anything other than wildebeest, and we’re working on managing a different (and much larger) set of data.
Post-flight processing includes geotagging the photos collected based on the tracklog. I’ve used Graphicconverter on the Mac but am trialling ExifTool which will work on Windows as well (though it’s command line).
Update 2016-08-27: see this Github Gist where I’m editing and keeping more notes.
To tag a folder of images, open Terminal on Mac/ Linux and enter:
Quantum GIS can now really compete with ArcGIS in terms of functionality and map creation. I miss a few things – proportional symbols for one – and the map layout for printing is not as easy – but the workflow is much easier, especially when editing shapefiles.
Installers for the current stable version of QGIS are maintained at William Kyngesburye’s siteincluding development builds from time to time, as well as the supporting frameworks required to run it.
Development builds (v 2.0 Alpha) are available from the Dakota Cartography site and updated nightly. These generally work really well – but many of the plugins no longer function.
You can run BOTH the stable and development versions side by side on your Mac – this is what I do, so far without a problem. One will be called QGIS.app and the other QGIS_2.0-dev.app; the only problem going back and forth between them may be compatibility between project file (.qgs) versions.
Installation of either the stable or dev versions requires installation of the supporting frameworks, then a standard drag-and-drop of the app itself:
Download and install the GDAL Complete framework (double click and install the package) – this gives you some required frameworks (applications) including GDAL, GEOS and SQLite (which are all useful in their own right) giving you command line access to those apps as well;
Download and install the GSL framework (double click and install the package);
Download and install QGIS (open the .dmg and drag the app to the Applications folder).
He also has installers for GRASS and PostGRESQL for the mac. I use the GRASS installer but find the Postgres.app installer (see below) far easier.
Browse for a spatial file and press space to see a preview of the geometry.
These are plugins for Quicklook and Spotlight for OSX, letting you preview shapefiles and other types of geographic data directly in the Finder or from QGIS while browsing for files.
This is invaluable.
With GISLook you can preview (press the spacebar while browsing) geometry or image data from shapefiles, .e00 interchange files, coverages, .asc grids, DEMs and others (see the home page for a complete list).
GISMeta while show the size of a raster grid file in the “get info” window in the Finder.
The easiest way to get this going is with the Postgres.app installer, giving you PostgreSQL 9.2 and PostGIS 2.02. Download, drag-and-drop, done.
I have battled with installing PostgreSQL and PostGIS on the Mac with varying results – homebrew or the packages from Kyngchaos can sometimes get it installed, but then the various frameworks or QGIS plugins (Python) don’t play well together.
Kickstarter certainly seems interesting; I’ve been browsing their site (and, in doing so, found two excellent little projects that seemed worthwhile and put some cash towards them) and taking some notes on what seems to succeed and what doesn’t. With all the interest in drones and wildlife survey, I was thinking that it might be fun to get a drone project funded through Kickstarter.
In a later moment of creative procrastination (avoiding all the other projects I have to do), I found a database of all the Kickstarter projects from about a year ago – 45,000 of them or so. Data on category, subcategory, goals, and the funded percentages. Did a little exploring in R, hence the not-very-pretty graphs below.
I often need to provide coordinates to light aircraft pilots – and most of them still use degree-minute-second notation (DMS) for charts and GPS. If we can’t upload flight plans and waypoints directly to the GPS I need to provide tables of DMS points – while QGIS can display in DMS in the canvas, it doesn’t have built-in functions for calculating and filling attribute fields.
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.
Enable “Allow installation of apps from unknown sources” – Settings|Security.
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).
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.
Confirm that you want to install (standard Android dialogue) – takes about 2 minutes to finish this stage.
Run QGIS: “Unpacking post-install data” … 10 seconds.
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.
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.
Tips and Tricks
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.
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).
Thanks again to Marco Bernasocchi for porting and continuing to develop QGIS for Android – if it’s useful, you should really make a donation!