One of the things that comes up in the intro to QGIS class are plugins. Plugins are an excellent way to extend functionality of QGIS. I used to make you pick and tell me why the plugin you installed was awesome. Generally I found that everyone was over whelmed and couldn’t decide in 20 minutes. I was having a conversation with a client and the question of plugins came up. So what plugins do I tell people use? So what do I use and how does that relate to ArcGIS Desktop?
This isn’t all the ones you could use – just the ones I use weekly (sometimes daily). Some of these are in core (i.e. you get them when you download QGIS) and some you have to download through the plugin manager.
Azimuth and Distance Plugin – What happens when someone hands you a pile of bearings and distances and wants you to build a property boundary? This plugin makes it pretty easy to put all that surveyed information into QGIS only to see it not close at the end (ha).
DB Manager – This plugin comes in core. It works with PostGIS and Spatialite. Since that’s what I use (and shapefiles occasionally) it works. For those of you in MSSQL land or Oracle land – there’s probably other ways to pass SQL commands to a database. You can import and export data in and out of those two databases. You can drag and drop data into QGIS. It’s a handy plugin if you’re using databases (postgis and spatialite) to store your data and I’m doing that very thing more and more these days.
Digitizing Tools - There were certain things I missed when making the transition from ArcGIS. I missed explode – this plugin provides provides that functionality. I missed clip (the one under the editor toolbar) and that is back. Cut layers, flip lines, and fill gaps between polygons. I don’t use every tool – but it adds enough tools I like to make it work.
Grass 7 – At the time this is written 2.12 is out. I made the jump from 2.8.X to 2.12 in the last few months. For those of you in ArcGIS land you have this extension called Spatial Analyst and several other “analyst” extensions. This plugin connects you to the underlying GRASS Software install and lets you view and run GRASS Commands from within QGIS. The big deal is – GRASS 7. For those of you who have opened GRASS and have went “Oh.My.GOD” – you are still going to do this….but it’s a lot easier to use. This plugin makes it easier. You get GRASS Software’s 30 year goodness into your GIS. Process Lidar….Pan Sharpen Landsat…and build networked vector datasets – and more.
Spatial Query Plugin – This plugin offers about every select by location choice you can come up with at any given time. Add two layers to the map create a new selection based on your parameters…and there are a lot of parameters. This one comes in core and it’s one I never turn off.
Topology Checker, Geometry Snapper, Geometry Checker – So I put three plugins in one description…why? Well – they are all three doing one thing – making better data. They are just all going about it differently. The one I use the most and will continue to use is topology checker. You can build topology rules and look at your data and look for errors. I haven’t used the other two enough yet but I’m working on it. More choices are good – and between these three you shouldn’t ‘bad’ data – and by bad I’m talking about Geometry.
Group Stats – Take your data and summarize it. Make Pivot Tables. Look at your shapefiles and Databases in different ways. It’s not the most intuitive plugin – but it can allow you to look at your data as if you had arceditor or ArcINFO and the much loved Frequency command. Granted if you have your data residing in a database you can throw SQL statements at it but it you don’t (or you want to do this graphically) this is your plugin.
AutoTrace – I love the trace tool in ArcGIS. Lutra Consulting developed something very similar to trace called AutoTrace. You add a new layer and you can trace an existing layer by pressing a combination of shift and ctrl to replicate that existing feature. As I sit here typing this I’ve only used it with polygons and not lines – but it works. It just takes a little gritting your teeth if you’re an avid ArcGIS user.
Georeferencer – When you get an unreferenced map/image and you want to georeference it? Georerferencer. It comes with core. Once you are done – you can add it to your QGIS Project. Polynomial 1, 2, or 3? Helmert? Projective? It’s here. I actually like having two windows for Georeferencing. Having them in one window is novel with ArcGIS – but I’m weird. I like them in two windows.
QuickMapServices – yes and for all of my “I USE QGIS” talking I do I just found this plugin. What does it do? Well – consider it a drop in replacement for openlayers. I love the openlayers plugin (and the web software) but I finally made it to a place where I dropped it out of the class. Why? It pulls in a lot of imagery sources (like Google) except you can’t make a map with it. With QuickMapServices you can make a layout. NOW – I saw all of that to say this plugin pulls in a lot of services and I’m not sure on how clear the licensing is – like with the openlayers plugin. I love pulling in Google imagery but you are forbidden from doing data collection with that layer – and to me the temptation is to great to have it sitting there….but I do have it sitting there.
What else do I use? There are a lot of things and not enough time. All of these are the weekly plugins I grab and use. There are others I use more sparingly like some of the CAD Tools or the MetaSearch Client. There’s a plugin that lets you draw squares and rectangles. There is one for surveying. There are probably a ton of others that I would find useful I haven’t stumbled onto them yet.
Does everyone need the ones mentioned above? I have no idea. I find them useful and I’m up to about 90% use of QGIS in my every day world. I would suggest giving them a whirl and if you have one I left out leave a comment. I’m all for spreading the knowledge.