Draw Effects & Blend Modes in QGIS
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My presentation from the 2018 FOSS4G UK conference in London, at Ordnance Survey's Geovation Hub, 9th March 2018.
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Draw Effects & Blend Modes in QGIS
- 1. Draw Effects and Blend Modes in QGIS Tom Armitage @MapNav_Tom
- 4. Blend Modes
- 5. Blend Modes
- 6. Blend Modes
- 7. Blend Modes 4 Groups • Lighten • Darken • Contrast • Inversion & Cancellation
- 8. Blend Modes
- 9. Blend Modes
- 14. Contrast Group Overlay Soft Light
- 15. Contrast Group Soft Light Hard Light
- 17. Blend Modes
- 18. Blend Modes
- 19. Blend Modes
- 20. Blend Modes
- 21. Draw Effects Inner Glow Inner Shadow Outer Glow Drop Shadow Blur Colourize Transform
- 22. outer GLow
- 23. outer GLow
- 24. outer GLow
- 25. outer GLow
- 26. outer GLow
- 27. outer GLow
- 28. BLur
- 29. BLur
- 30. BLur
- 31. Firefly Map
- 32. Firefly Map
- 33. Firefly Map
- 34. Firefly Map
- 35. Firefly Map
- 36. Firefly Map
- 37. Firefly Map
- 38. LightSabre maps
- 39. …on Polygons
- 40. …on Polygons
- 41. …on labelling
- 42. …on Print maps
- 43. Serious Points • • “Serious” Cartographic applications • Reduced need for other Software
- 44. Want to learn more? • http://edina.ed.ac.uk • tom.armitage@ed.ac.uk • @MapNav_Tom • http://learnGIS.uk • https://www.linkedin.com/in/tomarmitagegeo/
Editor's Notes
- Good afternoon. My name Tom Armitage from EDINA, a the University of Edinburgh. For those of you who have used maps in Higher Education over the last 20 years you will know us best as the people who bring you Digimap. I’m going to spend the next half hour talking about Draw Effects and Blend modes in QGIS, that’s too dull CLICK
- Let’s talk about Lightsaber maps! But what does that mean?
- A while ago I spotted a blog post by the excellent cartographer John Nelson. He wrote about what he called Firefly Cartography and in his post he mentioned that the lines glow like lightsabers, and so light sabre maps were born. The post was great but as John works for Esri his solution was written for ArcGIS. This is a story of how to create these maps in QGIS.
- Let’s start with blend modes So, who has used blend modes in their map? For those that haven’t when you have several layers on a map you generally want to see them at the same time and normally you’d reach for the transparency slder and get this: Click: Blend modes are the secret sauce that produce a map like this: Click geology data shows its colours more truly the hill shading adds pop, without dulling the flatter areas of the map. I love blend modes, but I must admit I had no idea what they actually are.
- Let’s start with blend modes So, who has used blend modes in their map? For those that haven’t when you have several layers on a map you generally want to see them at the same time and normally you’d reach for the transparency slder and get this: Click: Blend modes are the secret sauce that produce a map like this: Click geology data shows its colours more truly the hill shading adds pop, without dulling the flatter areas of the map. I love blend modes, but I must admit I had no idea what they actually are.
- Let’s start with blend modes So, who has used blend modes in their map? For those that haven’t when you have several layers on a map you generally want to see them at the same time and normally you’d reach for the transparency slder and get this: Click: Blend modes are the secret sauce that produce a map like this: Click geology data shows its colours more truly the hill shading adds pop, without dulling the flatter areas of the map. I love blend modes, but I must admit I had no idea what they actually are.
- There are currently 12 blend modes in QGIS divided into 4 groups. They all work on different elements of the colours you use: saturation, hue or the amount of black/white. I wanted to know more so I did a little experiment.
- I put together a matrix of colours and shades see what they all did.
- I put together a matrix of colours and shades see what they all did.
- Firstly the lighten group:If the pixels of the selected layer are lighter than the ones on the layers below, they are kept in the image If the pixels in the layer are darker, they are replaced with the pixels on the layers below (they show through to the selected layer). The group includes lighten, screen, dodge and Addition. Each one producing a more intense effect. Screen: As an analogy, imagine the selected layer and the underlying layer as being 35mm slides.
- Firstly the lighten group:If the pixels of the selected layer are lighter than the ones on the layers below, they are kept in the image If the pixels in the layer are darker, they are replaced with the pixels on the layers below (they show through to the selected layer). The group includes lighten, screen, dodge and Addition. Each one producing a more intense effect. Screen: As an analogy, imagine the selected layer and the underlying layer as being 35mm slides.
- Darken, basically the opposite of lighten: If the pixels of the selected layer are darker than the ones on the layers below, they are kept in the image. If the pixels in the layer are lighter, they are replaced with the tones on the layers below (they show through to the selected layer), so basically the darker tones of all layers are kept. Multiply: The best mode for adding colours on to a lighter base map. Works by multiplying the luminance levels of the current layer’s pixels with the pixels in the layers below. Burn: Darker than Multiply, with more highly saturated mid-tones and reduced highlights.
- Darken, basically the opposite of lighten: If the pixels of the selected layer are darker than the ones on the layers below, they are kept in the image. If the pixels in the layer are lighter, they are replaced with the tones on the layers below (they show through to the selected layer), so basically the darker tones of all layers are kept. Multiply: The best mode for adding colours on to a lighter base map. Works by multiplying the luminance levels of the current layer’s pixels with the pixels in the layers below. Burn: Darker than Multiply, with more highly saturated mid-tones and reduced highlights.
- All of the Contrast modes work by lightening the lightest pixels, darkening the darkest pixels, and dropping the gray mid-tones (50% gray). Combinations of the lightening and darkening modes from the Lighten and Darken groups. Overlay: Uses a combination of the Screen blend mode on the lighter pixels, and the Multiply blend mode on the darker pixels. Softer and more organic Hard light: Uses a combination of the Dodge and Burn half-strength application of these modes. much stronger effect particularly where saturation is high.
- All of the Contrast modes work by lightening the lightest pixels, darkening the darkest pixels, and dropping the gray mid-tones (50% gray). Combinations of the lightening and darkening modes from the Lighten and Darken groups. Overlay: Uses a combination of the Screen blend mode on the lighter pixels, and the Multiply blend mode on the darker pixels. Softer and more organic Hard light: Uses a combination of the Dodge and Burn half-strength application of these modes. much stronger effect particularly where saturation is high.
- Difference is part of a wider group of blend modes called the inversion group. With this blend mode, similar colors cancel each other, and the resulting color is black. Subtract is part of the wider Cancellation group. Similar to the Difference mode. So it’s a lot to take in but hopefully the groups make sense but really nothing can beat trial and error!
- Where are these things? You can add them to your layers, or to the individual features within layers , or to the draw effects we are going to talk about next! They are even found on labels and elements in the print composer, just look for the Rendering section.
- Where are these things? You can add them to your layers, or to the individual features within layers , or to the draw effects we are going to talk about next! They are even found on labels and elements in the print composer, just look for the Rendering section.
- Where are these things? You can add them to your layers, or to the individual features within layers , or to the draw effects we are going to talk about next! They are even found on labels and elements in the print composer, just look for the Rendering section.
- Where are these things? You can add them to your layers, or to the individual features within layers , or to the draw effects we are going to talk about next! They are even found on labels and elements in the print composer, just look for the Rendering section.
- SO now lets look at some draw effects, there are 7 different effects you can add to vector features in QGIS. Inner and outer glows, inner and drop shadows and you can also Blur, Transform and colourize the features too. I’m going to concentrate on the features most useful for making lightsabre and firefly maps.
- This nicely adds a glow to your feature sort of like a dead Jedi master. Click You can add this to your layer and like the blend mode you can add it at a feature level. Click Here are all the counties and Click this is what they look like with the effect applied to each one. As the effects are drawn individually you need to use a transparent fill or blend mode to see what is going on. Click So you can start to see some lightsabre like lines starting to appear. Its not as clumsy or random as a laser, an elegant pointer for a more civilised age.
- This nicely adds a glow to your feature sort of like a dead Jedi master. Click You can add this to your layer and like the blend mode you can add it at a feature level. Click Here are all the counties and Click this is what they look like with the effect applied to each one. As the effects are drawn individually you need to use a transparent fill or blend mode to see what is going on. Click So you can start to see some lightsabre like lines starting to appear. Its not as clumsy or random as a laser, an elegant pointer for a more civilised age.
- This nicely adds a glow to your feature sort of like a dead Jedi master. Click You can add this to your layer and like the blend mode you can add it at a feature level. Click Here are all the counties and Click this is what they look like with the effect applied to each one. As the effects are drawn individually you need to use a transparent fill or blend mode to see what is going on. Click So you can start to see some lightsabre like lines starting to appear. Its not as clumsy or random as a laser, an elegant pointer for a more civilised age.
- This nicely adds a glow to your feature sort of like a dead Jedi master. Click You can add this to your layer and like the blend mode you can add it at a feature level. Click Here are all the counties and Click this is what they look like with the effect applied to each one. As the effects are drawn individually you need to use a transparent fill or blend mode to see what is going on. Click So you can start to see some lightsabre like lines starting to appear. Its not as clumsy or random as a laser, an elegant pointer for a more civilised age.
- This nicely adds a glow to your feature sort of like a dead Jedi master. Click You can add this to your layer and like the blend mode you can add it at a feature level. Click Here are all the counties and Click this is what they look like with the effect applied to each one. As the effects are drawn individually you need to use a transparent fill or blend mode to see what is going on. Click So you can start to see some lightsabre like lines starting to appear. Its not as clumsy or random as a laser, an elegant pointer for a more civilised age.
- This nicely adds a glow to your feature sort of like a dead Jedi master. Click You can add this to your layer and like the blend mode you can add it at a feature level. Click Here are all the counties and Click this is what they look like with the effect applied to each one. As the effects are drawn individually you need to use a transparent fill or blend mode to see what is going on. Click So you can start to see some lightsabre like lines starting to appear. Its not as clumsy or random as a laser, an elegant pointer for a more civilised age.
- Blur is useful for softening the hard edges of features, again when you turn it up high you can see the sort of misty backgrounds you can put around features.
- Blur is useful for softening the hard edges of features, again when you turn it up high you can see the sort of misty backgrounds you can put around features.
- Blur is useful for softening the hard edges of features, again when you turn it up high you can see the sort of misty backgrounds you can put around features.
- So here is the map that started this, made in ArcGIS by John Nelson: multiple layers of a special png blurry marker, made in a graphics package. Each increasing in size and tinted a different colour. There are some overlays to darken the world map, and transparency is used to bring the layers together so you can see some of the map detail below. Ultimate control …And it’s gorgeous!
- I QGIS it is just one layer with a blurred marker with three outer glows of increasing size. And I did add a cheeky bit of lens flare to the points by overlaying some simple cross hair symbols.
- I QGIS it is just one layer with a blurred marker with three outer glows of increasing size. And I did add a cheeky bit of lens flare to the points by overlaying some simple cross hair symbols.
- I QGIS it is just one layer with a blurred marker with three outer glows of increasing size. And I did add a cheeky bit of lens flare to the points by overlaying some simple cross hair symbols.
- I QGIS it is just one layer with a blurred marker with three outer glows of increasing size. And I did add a cheeky bit of lens flare to the points by overlaying some simple cross hair symbols.
- I QGIS it is just one layer with a blurred marker with three outer glows of increasing size. And I did add a cheeky bit of lens flare to the points by overlaying some simple cross hair symbols.
- Here is the result A lighten blend mode has been used to bring it all together and the world map below was desaturated and dimmed all in QGIS. No other software was used I still prefer John’s map but in QGIS I could get something very similar with a few simple steps… Here are a few more examples:
- I used a single blue outer glow to make these lightsabre lines. In this map the draw effects are on the features not the layer, and as there is a separate line for each bus route the most well used roads glow with more intensity than the others.
- A simple green outer glow on white land outlines.
- These polygons have a slightly different method applied, instead of separate coloured glows I used a single glow with a colour ramp on a single outer glow. This looks good here but it didn’t work so well when applied at the feature level on the points.
- These labels have a glow effect on them but you can see there is also the option to add blend modes, to both the text and the buffer.
- And finally, yes blend modes have made it into the print composer so your overlays and labels can be integrated into the map.
- Impact, a bit over the top, but it catches the eye and gets data and so the research behind it noticed. Some of these techniques can produce some great cartography, coastal effects, pollution clouds and blending in labels are all areas of “Serious” cartography that can be enhanced with these tools. Which brings me on to my last point, these options mean that you can now get away without the expense or added complexity of putting your map through a graphics package in many instances!
- Thank you for listening.