North River Geographic Systems Inc

Spatial Problem Solving

Cartography

QGIS Leader Lines for Labels

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So way back when…..I was working in a production map shop and I had to make a map of a Nuclear Plant. The fun part being it was all manual. So we would use a lettering machine to place the labels and legend on the enlarged photo. We would manually trace all the features on an overlay.

Flash forward and we’re using ArcINFO and placing annotation and then drawing leader lines pointing to the features on an OrthoPhoto.

Last week and I had the chance to do something I don’t normally get to do: make a cartographic map in QGIS. I needed to make leader/callout lines from the labels back to the polygons. I didn’t want to manually draw in leader lines. Searching led me to two posts:

I ended up running with the kartoza example although both helped me understand how to get this working. So for the not too faint of heart……Here goes. I have some polygons on which I need to “cleanup labels” and leader lines would help in that regard. I could pull the labels away from the very small polygons I have and attach them back with a line.

The key to all of this ais Geometry Generators. The basics are you can use code and expressions in QGIS to draw Geometry. So I’m going to draw leader lines from my label to my polygon with some code (that I copied from Kartoza’s example – Hey to Kartoza). My data is Categorized. So I’m starting off with this:

So I’m going to click on Conservation Easement and add a symbol. The symbol will be a geometry generator. Just as a little background – I’m stacking symbology. So I’m adding another symbol to my yellow symbol by using the plus button on the symbol selector. I’m defining the type as a Geometry Generator and the Geometry Type as a line.

 

So what happens with the code I so skillfully pasted into the symbol selector?

make_line(
closest_point($geometry,
make_point( “auxiliary_storage_labeling_positionx” , “auxiliary_storage_labeling_positiony” )),
make_point( “auxiliary_storage_labeling_positionx” , “auxiliary_storage_labeling_positiony” )
)

The code says make a line using the closest point on the polygon and anchor it with the location of the label. Now something happens when I use the label toolbar to move my labels away from the polygons:

Now I have leader or callout lines back to my polygon. I’ll need to add a geometry generator to each category to give me lines for every category. The picky side of me is thinking for 100% control I should manually draw them in (but I’m not). If you read Kartoza’s post they have a more elegant final solution to deal with lines running over your labels. Looking at this now I need to move 210 back to the center of it’s polygon since it’s drawing the leader line under the polygon.Overall – Not bad.

 

Map Competition for Georgia Students

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…and from Georgia URISA:

Hello Students!

Announcing our

“Online Map Competition”

This map competition it is an opportunity for Georgia University/College students to share their best maps with others who appreciate quality cartography, innovation and finally get recognition for their talents.

This is an online competition.  All maps/poster and links need to be submitted by midnight of May 10thto  urisaonlinemapcompetition@gmail.com with a minimum half a page statement that provides context of the submission, i.e. its purpose, how it may be used, how it was created etc…, and a cover page that will include:

  • Student information, including name, address, phone number, email address.
  • Degree program (e.g., M.A.), cartography/GIS instructor’s name.
  • Graduation Date
  • Institutional affiliation

Maps will be judged based on the following:

  • Standard Map Elements: Title, legend, scale etc: 15 points
  • Balance and Layout: Does map appear well-balanced to the eye? Are some areas of the map blank while other areas are crowded: 10 points
  • Drafting Technical Quality: Technical involvement; difficulties: 20 points
  • Detail Thoroughness: Is there too little detail? Is there too much detail? Does it extend into every passage? Is it consistent throughout the entire map? Is the detail easy to understand or is it confusing? Does the detail match the legend or the list of symbols? What would be the use of the map? Does the map show the purpose: 15 points
  • Visual Impact: Does the cartography make the subject interesting or boring? Overall, does the map look good: 20 points
  • Innovations, new methods which enhance the understanding of the map: 20 points

 100 points is a maximum that student can acquire based on above requirements.

First, second and third place will receive a prize. Prizes to be announced soon! The rest of the participants will get recognition in the URISA newsletter and “swag.” 

Maps need to be submitted by Midnight of May 10th to urisaonlinemapcompetition@gmail.com, confirmation email will be an indication of the submission.

QGIS: The Label toolbar

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You’re sitting in a class…..back up – You’re teaching a class and and someone goes “Hey – there’s this QGIS Label Toolbar. How do it work?”.

I’m probably better at making a map than I believe. I really don’t enjoy it because with every map Green was always a problem. “Can you make this green ‘greener’?”. I would get upset and go “OK” and immediately make it too green. Way back in my career I was working on a Spill Plan Prevention Control and Countermeasures map (I think that’s SPCC). This map was all manual back in the day. We had a plan to make it “digital”. So we scanned a photo (and didn’t georeference it) and started laying out ArcINFO Annotation on it. At some point we scanned another map and had to move everything (not georeferenced) again. Then at some point we decided georeferencing the map was a good idea so I had to move all the annotation. Again. Anytime you say “label this feature” I break out in a sweat to this day.

So I sat this weekend with the whole goal of making the QGIS Label Toolbar Active. The best I could do was this:

Selection_395

I finally “Read the Manual” and found that the label toolbar is Attribute based. So if I add some Attributes to my data layer:

  • x – decimal number – Length 12 Precision 3
  • y – decimal number – Length 12 Precision 3
  • rotation – decimal number – Length 12 Precision 3
  • visibility – integer – Length 1

…..and then I assign those attributes to the label properties:

 

Selection_010 Selection_012

…..and then I edit my layer:

Selection_009

I can now move my labeling all over the place to make a better map. I can turn labels off. I can rotate the labels. Of course I’m not even discussing the Rule based labeling and all the joy you can have there.

Anyway – I left a tutorial I need to clean up a bit over HERE that should at least get you started.

 

FOSS4GNA 2016 Program

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Emails are flying so I wanted to throw something up here

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Confession: I’m on the conference committee. The final count came down to these numbers: 93 full talks, 36 half talks, 10 workshops, and 3 keynotes. You may look at this and go “OMG they are going to be talking about how to github a geojson raster into the cloud using geojava.node.whatmacallit and this is going to be nothing but confusing”

To randomly pick 5 talks:

Hiroshima Archive: The goal of the “Hiroshima Archive” is to ensure that future generations will be able to learn the true cost of atomic warfare. Using Cesium, the archive is able to provide a personalized experience. A user could be viewing a 1945 map while browsing survivors’ accounts and photos. They could then choose to switch to modern aerial photography to see how the location has changed since.

Processing Raster Data for Online Use: Have you seen georeferenced historical maps online that just look…fuzzy? That’s what we started with at the Emory Center for Digital Scholarship, and we would like to share the steps we’ve found to get clear, legible, zoomable map overlays.

Cartography with InkScape: Sometimes your map needs a little extra polish. In this talk, I will outline my workflow for bringing maps from QGIS into Inkscape and exporting to commonly used formats to produces a finished professional-quality map. It will include “do’s” and “don’ts” to help you develop your own workflow and avoid common pitfalls, as well as some features unique to Inkscape such as filters.

PostGIS Spatial Tricks: This talk will showcase spatial feats you can do with PostGIS Special focus will be given to features new in PostGIS 2.2 and upcoming PostGIS 2.3.

Precision Ag and Open Spatial Technologies: Autonomous Vehicles, Drones and Data Driven decisions happening on a sub inch level. A city of the future? No, a farm today. Come find out the current Precision Agricultural techniques for data collection, analysis and dissimulation and where FOSS4G tech plays a key role. From harvesting millions of data points generated from every vehicle on the farm, to the corporate dashboard and reports, FOSS4G plays a role.

State of QGIS: State of QGIS reviews new and noteworthy features for the QGIS project. This talk will cover both Desktop and Server components from version 2.14 just released by the community.

So if you’ve never been to one of these things – that’s some of the crazy good talks you’ll see. Even if you’re all ESRI all Day this is good information. I know we are going up against the old ESRI SERUG conference – but I think as far as pushing the envelope of technical talks have everyone else beat.

Good People Come to Raleigh!

ArcGIS lyr files and QGIS qlr files

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I spend a ton of time talking about QGIS up here. I like QGIS. I like GIS in general and there are some days I wonder if I’m unintentionally ignoring the ESRI side of life. Actually I don’t for clients – 20+ years of Using ESRI software leaves me in a good spot to answer all sorts of questions.

So I went to visit a potential client this last week. It’s funny how a 20 minute visit can turn into a 3 hour discussion of GIS. Short story – we covered two pieces of software: ArcGIS, and QGIS. Shorter story – they are moving from ArcGIS to QGIS.  It nice getting the view of someone casually using GIS (both packages) software who doesn’t do this day in and day out.

The conversation covered a lot of ground. One of things we talked about was lyr files. As a former instructor in the dark arts of ArcGIS, lyr files were one of those things everyone seemed to know something about and no one was entirely sure what to do with them. You see a lot of “Can I use LYR files in QGIS?” Well – no but here is a story on lyr and qlr files.

The short story on lyr files:

1. Symbolize your data layer in ArcGIS.

arcgis_lyr

2. You can even set up a definition query to single out a particular feature in your layer. In this case I’ve singled out a tract of land a client works.

3. Right click your layer in the table of contents and save a lyr file.

Lyr files are super handy. You can symbolize data. You can label. You can set definition queries and save it all to a lyr file. ArcGIS treats an lyr like data (BUT IT’S NOT). You can add them by hitting the add data button so a lot of times people can and will get confused and think an lyr is data. So you will get emails from people going “Here I sent you some data” and it’s a bunch of lyr files. I generally make it a point to tell people to name them and make a different folder and keep them all there. Treat them as part of your project. Treat them as important. Don’t think they are data though.

BUT – What about QGIS?

1. Symbolize your data in QGIS

qgis_lyr

 

2. You can even set up a feature subset (definition query) to single out a particular feature in your layer. In this case I’ve singled out a tract of land a client works.

3. Right click your layer Layer Panel and save a layer definition file (a qlr).

Notice I tried to give this an identical three step description. You can’t add qlr files with an “add data” button in QGIS. You can drag and drop it onto your map canvas or use Layer -> Add from Layer Definition File to use it. No data is saved. This is just a pointer back to your data with symbology and other info saved.

Quickly…….

  • So can you use a lyr with QGIS? Nope.
  • Can you use a qlr with ArcGIS? Nope.
  • Can you define symbology in ArcGIS from a lyr file? Yes! Just import your symbology and choose your lyr and if the attribution matches you are good.
  • Can you define symbology in QGIS from a qlr file? No – but that is what qml and sld files are for. Save those from your property menu and you can use those to symbolize other data.
  • Can you open a lyr in a text editor and see how it works? NO…I think the greatest shortcoming of lyr is this.
  • Can you open a qlr in a text editor and see how it works? YES…it’s an XML based file.

So as always make your life easier. Save lyr and qlr files with your data because you don’t want to spent tons of time symbolizing it over and over. Remember – neither qlr or lyr hold any data – just symbology and data queries. So don’t email your friends or consultants lyr or glr files.

Explore more here and here!

**Update

 

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