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Thread: [Award Winner] Some pointers for using GIS

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  1. #1
    Software Dev/Rep Hai-Etlik's Avatar
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    It's been a while but it's time for another part in this tutorial. I'm using a newer version of QGIS (1. now so it looks a bit different.

    As of the last entry, you should have a map that looks something like this:

    Click image for larger version. 

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    Having a nice map like that, you will probably want to get it out of QGIS in some form so you can work on it in a graphics program. The quick and dirty way is with "Save As Image" which we've allready used. If you want to get a bit fancier you can use the Print Composer.

    Go to File -> New Print Composer

    This will bring up a new Print Composer window.

    Click image for larger version. 

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    This is a basic vector graphics editor, with some specialized extra abilities.

    First, you'll want to add a map. Name:  add-map.png
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    Drag out a box on the page and it should be filled with your map, with approximately the same extent as in the main window.

    Click image for larger version. 

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    You can adjust the box with the Select/Move Item tool, and adjust the position of the content of the map with the Move Item Content tool Name:  move.png
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    You can also adjust the "Item Properties" to specify exact extent and scale, or graphical properties like the border. This tab will vary to present options for whichever item in the image you have selected.

    Along with the "Item Properties" tab is the "Composition" tab which lets you specify options for the page as a whole.
    Click image for larger version. 

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    You can also add a Legend and a Scale Bar.Name:  add-legend.png
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    In the Item properties you can adjust the titles, fonts, grouping, and layers displayed for the legend and the shape of the Scale bar.

    In the case of the scale bar, remember that most projections use Meters as their units "geographic" projections use degrees (which should have a scale bar) and a few older projections use feet. The "Segment size" then is the number of meters each bar on the scale represents. So if you want 250 km segments, you would enter 250*1000=250000. "Map units per bar" controls the numbers used to label the scale. If you want the scale labelled in Kilometres, then you would put in 1000.

    Right segments are the full size segments to the right of the 0 mark. You can also add smaller segments to the left that add up to one of the full segments. For instance, with our 250 km right segments, if we set sight segments to 4 and left segments to 5, then the scale would run from 0 km to 1000 km in 250 km steps on the right, and from 0 km to 250 km in 50 km steps on the left. You can also adjust the size font, spacing, and the visual style of the scale bar, and add a unit label.

    Click image for larger version. 

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    There are a lot of other options to work with, but as a graphics editor is more suited to this work, I suggest you just do the basics of setting up the map extent and the scale then export it.

    You have three options. You can export it as a raster image (you can set the resolution in the Composition tab). This is simple but you won't have access to layers or geometry so you'll have to trace over it. It is however the most reliable option and if you were planning to trace over it anyway, this is simplest.

    You can export as a PDF and then load into a vector graphics editor like Inkscape or Illustrator. There can sometimes be minor glytches in symbolization when using this option.

    You can export as an SVG and and load into a vector graphics editor as with PDF. This is the buggiest option so be wary. They may improve this option in future, particularly in terms of making it easier to edit in Inkscape. At the moment it doesn't use groups, or defined symbols so the resulting file can be messy.

    If you plan to use the vector export options, I'd strongly recommend staying away from fancy symbology options like patterns and stacked symbolizers.

  2. #2
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    Sorry to necropost but I just came across a package that reckons it can convert from SVG to SHP. It's called reaConverter https://www.reaconverter.com/convert/svg_to_shp.html and sells for $49.99 US

    I haven't tried it and don't have the cash spare at present (the free version doesn't do vector formats) but obviously someone has come across this as an issue elsewhere ;-)

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